• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 List of Tables
 List of Figures
 Introduction
 Review of literature
 Materials and methods
 Results
 Discussion
 Summary
 Bibliography
 Biographical sketch
 Copyright














Title: Fruit quality of strawberry (Fragaria virginiana Duchesne X Fragaria chiloensis L.) as affected by potassium and nitrogen nutrition
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Title: Fruit quality of strawberry (Fragaria virginiana Duchesne X Fragaria chiloensis L.) as affected by potassium and nitrogen nutrition
Series Title: Fruit quality of strawberry (Fragaria virginiana Duchesne X Fragaria chiloensis L.) as affected by potassium and nitrogen nutrition
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Table of Contents
    Title Page
        Page i
    Acknowledgement
        Page ii
    List of Tables
        Page iii
        Page iv
        Page v
        Page vi
        Page vii
        Page viii
    List of Figures
        Page ix
    Introduction
        Page 1
        Page 2
    Review of literature
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Materials and methods
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
    Results
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
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        Page 91
        Page 92
        Page 93
        Page 94
        Page 95
        Page 96
    Discussion
        Page 97
        Page 98
        Page 99
        Page 100
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        Page 108
    Summary
        Page 109
        Page 110
        Page 111
        Page 112
    Bibliography
        Page 113
        Page 114
        Page 115
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
        Page 121
    Biographical sketch
        Page 122
        Page 123
    Copyright
        Copyright
Full Text













FRUIT QUALITY OF STRAWBERRY (Fragaria
virginiana Duchesne x Fragaria chiloensis L.) AS
AFFECTED BY POTASSIUM AND
NITROGEN NUTRITION





By
GOPAL KRISHNA SAXENA
SOP


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY










UNIVERSITY OF FLORIDA
April, 1967
















ACKNOWLEDGMENTS

I wish to express my deep appreciation and sincere

thanks to Dr. Salvadore Joseph Locascio for his advice, guidance

and interest throughout the course of my graduate work.

Thanks are also extended to Dr. V. F. Nettles, Mr. M. E.

Marvel, Dr. T. E. Humphreys,' and Dr. L. C. Hammond, members of

the supervisory committee, for rendering helpful suggestions

during the preparation of this manuscript.

Furthermore, I would like to mention Dr. F.,S. Jamison

for the encouragement, and Dr. B. D. Thompson for timely con-

sultations during this investigation. The help of Dr. Essam M.

Ahmed in the use of the shear press is appreciated.

For their patience and inspiration I am greatful to my

parents.

This work was made possible by the financial support

from the Vegetable Crops Department, University of Florida,

and The American Potash Institute to whom I am thankful.




















TABLE OF CONTENTS


ACKNOWLEDGMENTS . . . .


LIST OF TABLES . . . . .


LIST OF FIGURES . . . . .


INTRODUCTION . . . . . .


REVIEW OF LITERATURE . . . .


Effect of K and N Nutrition on
Effect of K and N Nutrition on
Fruit Yield . .. ...
Effect of K and N Nutrition on
of Foliage and Fruit . .


MATERIALS AND METHODS. . . .


Experiment I (1964-1965) . .
Experiment II (1965-1966). .
Cultural Practices and Yields.
Fruit Sampling . . . .
Storage of Fruit . . . .
Quality Measurements .. ..
Foliar Sampling. . . . .
Analytical Procedure .. ..
Statistical Analysis .. ..


RESULTS. . . . . . . .


Experiment I (1964-1965) . .
Experiment II (1965-1966). .


DISCUSSION . . . . . .


SUMMARY . . . . . .


BIBLIOGRAPHY . . . . . .


BIOGRAPHICAL SKETCH . . . .


. . . . . .


. . . . . .


. . . . . .


. . . . . .


. . . . . .


Fruit Quality . .
Plant Growth and



. . . . . .
Mineral Composition




. . . . . .

. . . . . .

. . . . . .
. . . . . .
. . . . . .


. . . o . o
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. . . . . .

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.. .. .. .


Page


ii


iv


ix


1


3


3


7


9


12


12
13
14
14
14
15
16
17
17


19


19
46


97


109


113


122
















LIST OF TABLES


Table Page

1. Acreage, production, yield per acre and total
value of Florida grown strawberries. . . . . 2

2. Orthogonal comparisons in Experiment I and
Experiment II. . . . . . . . . .. 18

3. Effect of potassium source and rate of potassium
and nitrogen on early yields of marketable and
cull strawberries, 1965. . . . . .. .. 20

4. Effect of potassium source and rate of potassium
and nitrogen on total yields of marketable and
cull strawberries, 1965. . . . .... . . 21

5. Effect of potassium source and rate of potassium
and nitrogen on shear resistance of fresh straw-
berries from March 26 and April 16, 1965 pickings. 22

6. Effect of potassium source and rate of potassium
and nitrogen on shear resistance of strawberries
from March 26 and April 16, 1965 pickings after
eight days in storage. . . . . . . .. .24

7. Effect of potassium source and rate of potassium
and nitrogen on soluble solids content of fresh
strawberries from March 26 and April 16, 1965
pickings.. . . . . . . . . . . 25

8. Effect of potassium source and rate of potassium
and nitrogen on soluble solids content of straw-
berries from March 26 and April 16, 1965 pickings
after eight days in storage. . . . . . ... 27

9. Effect of potassium source and rate of potassium
and nitrogen on dry matter content of fresh straw-
berries from March 26 and April 16, 1965 pickings. 29

10. Effect of potassium source and rate of potassium
and nitrogen on dry matter content of straw-
berries from March 26 and April 16, 1965 pickings
after eight days in storage. . . . . . .. .30









Table


11. Effect of potassium source and rate of potassium
and nitrogen on total titratable acidity of fresh
strawberries from March 26 and April 16, 1965
pickings . . . . . . . . . . 31

12. Effect of potassium source and rate of potassium
and nitrogen on total titratable acidity of straw-
berries from March 26 and April 16, 1965 pickings
after eight days in storage. . . . . . . 33

13. Effect of potassium source and rate of potassium
and nitrogen on total nitrogen content of straw-
berry fruits from March 26 and April 16, 1965
pickings . . . . . . . . ... . . 35

14. Effect of potassium source and rate of potassium
and nitrogen on potassium content of strawberry
fruits from March 26 and April 16, 1965 pickings .36

.1. Effect of potassium source and rate of potassium
and nitrogen on calcium content of strawberry
fruits from March 26 and April 16, 1965 pickings .38

16. Effect of potassium source and rate of potassium
and nitrogen on magnesium content of strawberry
fruits from March 26 and April 16, 1965 pickings .39

17. Effect of potassium source and rate of potassium
and nitrogen on total nitrogen content of straw-
berry foliage on March 26 and April 16, 1965 . . 41

18. Effect of potassium source and rate of potassium
and nitrogen on potassium content of strawberry
foliage on March 26 and April 16, 1965 . . . 42

19. Effect of potassium source and rate of potassium
and nitrogen on calcium content of strawberry
foliage on March 26 and April 16, 1965 ...... 44

20. Effect of potassium source and rate of potassium
and-nitrogen on magnesium content of strawberry
foliage on March 26 and April 16, 1965 ... . . 45

21. Effect of potassium source and rate of potassium
and nitrogen on early yields of marketable and
cull strawberries, 1966. . . . . . .. 47

22. Effect of potassium source and rate of potassium
and nitrogen on total yields of marketable and
cull strawberries, 1966. . .. .. . . .49


Page











23. Effect of potassium source and rate of potassium
and nitrogen on average size of fresh fruit from
March 25 and April 11, 1966 pickings . . ... .53

24. Effect of potassium source and rate of potassium
and nitrogen on total fresh and dry weight of
seven plant tops on May 31, 1966 . . . . . 54

25. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of fresh strawberries from April 11, 1966 picking. 58

26. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of fresh strawberries from April 18, 1966 picking. 59

27. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of fresh strawberries from May 2, 1966 picking . 60

28. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of strawberries from April 11, 1966 picking
after four days in storage . . . . . . 62

29. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of strawberries from April 18, 1966 picking
after four days in storage . . . . . . .. 63

30. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of strawberries from April 18, 1966 picking after
eight days in storage. . . . . . . . 64

31. Effect of potassium source and rate of potassium
and nitrogen on compression and shear resistance
of strawberries from May 2, 1966 picking after
eight days in storage. . . . . . . .. 65

32. Effect of potassium source and rate of potassium
and nitrogen on soluble solids content of fresh
strawberries from March 25, April 11, and April
18, 1966 pickings. . . . . . . . ... 68

33. Effect of potassium source and rate of potassium
and nitrogen on soluble solids content of straw-
berries from March 25, April 11, and April 18,
1966 pickings after storage for eight, four and
eight days respectively. . . . . . . ... 69


Table


Page











34. Effect of potassium source and rate of-potassium
and nitrogen on dry matter content of fresh straw-
berries from March 25, April 11, and April 18,
1966 pickings. . . . . . . . . . 71

35. Effect of potassium source and rate of potassium
and nitrogen on dry matter content of strawberries
from March 25, April 11, and April 18, 1966
pickings after storage for eight, four and
eight days respectively. . . . . . . ... 72

36. Effect of potassium source and rate of potassium
and nitrogen on total titratable acidity of fresh
strawberries from March 25, April 11, and April
18, 1966 pickings. . . . ..... ... .. 74

37. Effect of potassium source and rate of potassium
and nitrogen on total titratable acidity of
strawberries from March 25, April 11, and April
18, 1966 pickings after storage for eight, four,
and eight days storage respectively. .. .. . .77

38. Effect of potassium source and rate of potassium
and nitrogen on total nitrogen content of straw-
berry fruits from March 25, April 11, and April
18, 1966 pickings. . . . . . . . ... 78

39. Effect of potassium source and rate of potassium
and nitrogen on potassium content of strawberry
fruits from March 25, April 11, and April 18,
1966 pickings. . . . . . . . . ... 80

40. Effect of potassium source and rate of potassium
and nitrogen on calcium content of strawberry
fruits from March 25, April 11, and April 18,
1966 pickings. . . . . . . . . ... ..82

41. Effect of potassium source and rate of potassium
and nitrogen on magnesium content of strawberry
fruit from March 25, April 11, and April 18,
1966 pickings. .. .. . . . . . . . 84

42. Effect of potassium source and rate of potassium
and nitrogen on total nitrogen content of straw-
berry foliage on January 17 and March 17, 1966 . 86

43. Effect of potassium source and rate of potassium
and nitrogen.on total nitrogen content of straw-
berry foliage on April 18 and May 17, 1966.. .. .87


vii


Table


Page












44. Effect of potassium source and rate of potassium
and nitrogen on potassium content of strawberry
foliage on January 17 and March 17, 1966 . . .. .89

45. Effect of potassium source and rate of potassium
and nitrogen on potassium content of strawberry
foliage on April 18 and May 17, 1966 . . .. 90

46. Effect of potassium source and rate of potassium
and nitrogen on calcium content of strawberry
foliage on January 17 and March 17, 1966. ... .92

47. Effect of potassium source and rate of potassium
and nitrogen on calcium content of.strawberry
foliage on April 18 and May 17, 1966 . .. .. 93

48. Effect of potassium source and rate of potassium
and nitrogen on magnesium content of strawberry
foliage on January 17 and March 17, 1966. ... .94

49. Effect of potassium source and rate of potassium
and nitrogen on magnesium content of strawberry
foliage on April 18 and May 17, 1966 . . ... 95


viii


Page


Table
















LIST OF FIGURES


Figure Page

1. Yield of fruit (g per plot) at individual pickings
in the 1966 fruiting season as affected by various
rates of K . . . . . . . . . . 50

2. Yield of fruit (g per plot) at individual pickings
in the 1966 fruiting season as affected by various
rates of N . . . . .. . . . . . 51

3. Condition of plants from plots not receiving K,
at the end of the 1966 fruiting season . . . 56

4. Condition of plants from plots receiving 145
pounds per acre K as KC1, at the end of the
1966 fruiting season . . . . . . . . 56














INTRODUCTION

Strawberry (Fragaria virginiana Duchesne x Fragaria

chiloensis L.) yields in Florida have increased from 2,200

pounds per acre in 1959 to 9,100 pounds per acre in 1966 (Table

1). This yield increase is primarily due to the increased use

of the black polyethylene plastic mulch and an improved cultivar,

although adoption of other cultural practices such as soil

fumigation and better insect control have also contributed.

Black polyethylene plastic mulch has been reported to conserve

the soil moisture, and retain soil nutrients by keeping the

losses due to leaching at a minimum, and by controlling weeds.

Also the soil temperatures under plastic mulch are relatively

higher during cool periods (2, 70, 71, 74, 101). All these

factors contribute towards changing the soil micro-climate for

better plant growth. In addition, the fruit produced on the

plastic mulch is relatively cleaner.

Since all of the Florida grown strawberries are supplied

to the fresh market, a better fruit quality is always desirable.

Firmness of the fruit is considered to be a measure of storage

and handling properties of strawberries while fruit soluble

solids and acid content contribute towards the fruit flavor.

All these quality factors have been suggested to be affected

by N and K nutrition. Fertilization with K has been generally

believed to increase the firmness of the strawberry fruit. How-

ever, this has not been supported by published work (36, 110).

1


r










The use of N in contrast has been reported by several workers to

produce soft fruits (4, 18, 31, 42, 57, 87, 94). The source of

K has also been reported to influence the strawberry fruit yield

and quality (59, 80).

Most of the nutrition work with strawberries has been

done using the matted row system of production or sand culture,

and the experiments did not include tissue analysis to support

the conclusions.

The present investigation was conducted to study the

effect of K- source, and rates of K and N on plant growth,

fruit yield and fresh and stored fruit quality of strawberries.


Table 1. Acreage, production, yield per acre and
value of Florida grown strawberries*.


Total Average Total
Acres production yield-pounds value
Year harvested 1,000 pounds per acre $1,000


1959
1960
1961
1962
1963
1964
1965
1966

*Prepared
107, 108).


1,500
1,400
1,800
1,900
2,000
2,700
3,300
2,300

from U.S.D.A.


3,300 2,220
7,140 5,100
8,140 4,522
13,490 7,100
16,600 8,300
20,790 7,700
27,390 8,300
20,930 9,100

Agricultural Statistics


1,370
2,728
2,812
4,740
5,683
7,175
7,678
7,964

(104,105, 106,
















REVIEW OF LITERATURE

Effect of K and N Nutrition.on Fruit Quality

Most of the earlier work regarding the effect of macro-

nutrients on fruit quality has been centered around apples,

although strawberries have also been studied by many workers

(18, 19, 21, 22, 23, 26, 31, 32, 35, 36, 39, 42, 45, 50, 56,

57, 58, 59, 80, 93, 94). The following review covers work

primarily with strawberries, although other fruits have also

been included.

With apples, N and K were the two most common macro-

nutrients studied. Fruit quality has been reported to improve

with K fertilization, however, the results of N applications

have been conflicting. Very little work has been reported on

the specific effect of Ca and Mg, and the effect of P on apple

fruit quality has not been reported (20). With strawberries,

N and X have also been two commonly studied macro-nutrients.

The literature on strawberries indicates that.workers

have been primarily interested in fruit firmness as the criterion

for fruit quality and as a measure of the storability of fruit.

Firmness of strawberry fruit has been found to be positively

correlated with its dry matter content (45).

A positive correlation between the respiratory rate of

the fruit and fruit firmness and dry matter content have been

reported by Haller et al. (45). In a similar study, Overholser

3









et al. (88) showed that lower rates of respiration in straw-

berries were not correlated with greater fruit firmness, either

with mature or immature fruits. The keeping quality of the fruit

was affected by their initial firmness. Handschach (47) reported

that the firmness of fully ripe strawberry fruit was not cor-

related with its alcohol-insoluble solid content.

The effect of N fertilizers has been generally associated

with the weather condition. Under conditions of extremely warm

weather during a large portion of the picking season, plants

heavily fertilized with N, produced larger fruits as compared to

plots not fertilized with N. These larger fruits tended to be

soft. In cooler periods however, very little difference was

found, due to N fertilization (18). Heavy application of quickly

available N fertilizer in wet seasons produced detrimental re-

sults with strawberries (4). In this case, the losses were

primarily due to the presence of soft and green fruits. Spring

application of N fertilizer has been reported to produce soft

strawberries (42, 94). Kimbrough (57) indicated that weather

conditions, especially rainfall, had a decidedly greater effect

on strawberry fruit firmness, sugar and moisture contents, than

different fertilizer treatments. Production of softer fruits

due to the application of N fertilizers has also been reported

by Overholser and Claypool (87), and Darrow (31).

The fruit softening effect of N fertilization has been

reported to be an indirect one. Increased supply of N increases

the foliage growth, which makes fruits more susceptible to mold

growth during their development and transit (31, 32).









Several reports indicate that soft fruits are not always

associated with the application of N fertilizers. Application

of 100 pounds per acre N in sand culture did not reduce the

firmness of strawberries (26). It was also found that fruits

produced later in the season tended to be softer than those

produced in the early and mid-season. Furthermore, during

storage, decay was observed only in bruised fruits and was not

affected by the fertilizer treatment. Fruit handling during

picking and preparation for market was reported to have a greater

influence on the firmness than N fertilization (69). In this case,

the percentage of spoilage was approximately double in the roughly

handled strawberries as compared to the carefully handled ones.

Magness and Overley (77) with apples, and Webster and Gray (109)

with strawberries did not find any fruit softening effect of N

fertilization.

Fertilization with N has been reported to produce

strawberries low in acids, and total and reducing sugars (26,

42, 94). The soluble solids content of tomato fruit was also

found to be reduced with higherN- rates (68). Application of

N has also been shown to increase the catalase activity in

apples (41), and strawberries (42).

Archbold (3) indicated that a higher N content of apples,

in general, was accompanied by a higher rate of respiration. On

the other hand a lower N content of the fruit reduced the rate

of breakdown and increased the storage life of the fruit. A

higher N content was also found to be associated with a low

total titratable acidity. A similar increase in the fruit









respiratory rate with increased N supply has been reported by

several other workers (27, 36, 50, 87). Haynes (51), and Haynes

and Archbold (52) suggested that the properties which favor the

keeping quality of apples were a low N and high sucrose content.

Reports regarding the effect of K on fruit quality show

that increased K supply, in general, enhanced the strawberry

fruit quality. The effect of K on the fruit firmness has been

controversial. Cochran and Webster (26) showed that, as the

fruiting season progressed, plots where either 50 or 100 pounds

per acre K was applied, produced slightly firmer strawberry

fruits than where K was not applied. Weinberger (110), and

Degman and Weinberger (36) however, did not find increased

firmness or keeping quality of apples, peaches and strawberries,

due to application of K, either alone or with N and P. Fruits

from plots receiving K and N were not firmer at picking time,

thus K can not be considered as a counteractant in overcoming

the supposedly deleterious effect of N fertilizers on shipping

or keeping quality of the fruit. A six years study with apples

and peaches showed that in the absence of added K the fruits

were firmer at the picking time, but the fruit softened more

rapidly during storage (8). A definite reduction in the firmness

of Montmorency cherries, with increased levels of K was observed

by Curwen et al. (30). They found that N fertilization produced

firmer fruits.

Application of K fertilizer has been reported by a number

of workers to effect the chemical composition of strawberries.

Plots not receiving applied K produced strawberries lowest in









acid and sugar content, as compared to fruits from plots re-

ceiving K (58). Increased acid and sugar content with increased

K supply has been reported in apples (38), in tomatoes (84),

and in strawberries (19, 21, 22, 23, 100). Soluble solids

content and total titratable acidity of strawberry fruit have

been shown to increase as the foliar K level in two strawberry

cultivars increased from 0.5 to 2.0 per cent (93).

In general, KC1 has been shown to be a poor source of

K as compared to K2SO4. Matzner (80) reported a significant

yield reduction when KC1 was the source of K as compared with

K2SO4. However, the two sources of K did not affect the fruit

dry matter and sugar contents. From a similar study, higher

strawberry yields were obtained in the second and third year

where a fertilizer low in chloride was used as compared to one

high in chloride. Although, plant K content was higher when

fertilizer high in chloride was used (59).

Effect of K and N Nutrition on
Plant Growth and Fruit Yield

Literature regarding the effect of macro-element nutri-

tion on plant performance and fruit yield has been recently

reviewed (17).

Application of nitrogen fertilizers has been reported to

increase the fruit production and improve strawberry plant

growth. On a new soil in North Carolina a 60 pounds per acre

rate of N produced maximum yield of strawberry fruit (66).

Higher yields and larger plants of the "Florida-90" strawberries

were obtained by the application of 100 pounds per acre N as










compared to zero and 50 pounds per acre rates, with Ona and

Blanton soils in a pot experiment (37). Both the Ona and

Blanton soils were very low in nitrates. Similar yield re-

sponses to N fertilization have been reported by several other

workers (33, 61, 63, 76, 83, 99). The favorable effect of N

application on fruit yield has been attributed to the increased

flowering (75), and to increased root growth of strawberry

plants (64, 82). The yield of "Florida-90" strawberries grown

with black plastic mulch increased linearly with an increase in

the rate of 6-8-8 fertilizer up to 2,000 pounds per acre (74).

In several reports, N applications have been found

either to reduce the yield of strawberries or to have no definite

effect. Use of sodium nitrate was found to produce lower yields

of strawberries (53, 63, 111). Yields were not increased in

response to application of urea (52 pounds per acre) to straw-

berries (48). Yield increases with the application of N fer-

tilizers were not obtained by several others (6, 9, 10, 14, 28).

Such inconsistent responses to N fertilization are proba-

bly due to the variation in the soil N levels. Soils with a

high N content show very little or no response to applied N,

whereas, thosewith a low N content, show an increase in the fruit

yield (17, 98).

Fertilization with K in many cases has had no effect on

fruit yields. Application of 70 or 140 pounds per acre K to Ona

and Blanton soils did not produce increased yields of "Florida-

90" strawberries. The initial level of K20 in the Ona was 36

pounds per acre and in the Blanton soil, 187 pounds per acre (37).










In other works application of K fertilizer was reported to

increase the foliar content of K, but it did not increase the

yield of fruits (65, 66, 67, 90). Although above reports show a

lack of yield response to K fertilization, Darrow and Waldo (32),

reported a 29 per cent yield increase due to application of K,

as compared to unfertilized plots. Kirsch (61) emphasized that

K fertilization resulted in a yield increase only when it was

accompanied by the application of lime. Increased strawberry

yields due to K fertilization have also been reported by others

(58, 65, 89).

Effect of K and N .Nutrition on
Mineral Composition of Foliage and Fruit

Davis et al. (34), from a pot culture experiment with

strawberries, pointed out an antagonistic relationship between

the Ca and K supply. This was more evident at the deficiency

level than at the excess levels. Similar antagonism between

Ca and K has also been reported by Smith (95), and Smith and

Childers (96). The foliar Ca level was inversely related to

K content of the nutrient solution.

In general, during the period of flowering and fruiting

there is a heavy nutrient translocation from foliage to the

developing fruit. In a long-term experiment, omission of K

resulted in a reduction in the foliar concentration of K to a

point below the threshold value of 1.1 per cent K20 (16).

This period corresponded with a heavy withdrawal of K from the

foliage to the fruit and severe leaf scorch was observed in

these cases. A similar drop in the foliar N level during the









fruiting period was observed by several other workers (13, 15,

43, 44, 91). However, at the end of the fruiting period there

was a recovery in the foliar N levels. The foliar content of

Ca showed an increase as the season progressed (1).

Optimum foliar concentrations of different nutrient

elements have been reported by many workers. A 2.7 to 2.8

per cent N content in the foliage at the time of fruit ripening

was associated with the highest yield of marketable fruit.

Foliar N levels higher than these produced more vegetative growth

and reduced the fruit yield. Optimum foliar content of P and K

were reported to be 0.3 and 1.7 per cent, respectively (11, 12).

Martin (79), from a factorial experiment with strawberries found

a negative relationship between fruit yields and foliar content

of N and K. From sand culture experiments, Gruppe and Nurbachsch

(43), found that 2.35 to 2.40 per cent N and 0.28 to 0.32 per

cent P in the foliage corresponded with the maximum fruit yield.

Increased supply of nitrates reduced the K, but increased the

Ca and Mg in the foliage. In a later report (44), the yield

curves showed a 0.7 per cent K and 0.4 per cent Mg in the foliage

as the optimum levels for optimum plant growth and fruit yields

of strawberries. These reported optimum foliar levels of K

(0.7 per cent) appear to be lower than generally reported in the

literature. According to Smith and Childers (96), a 1.07 per

cent K content in the strawberry foliage is optimum for the maxi-

mum fruit yield. This value according to Bould (12) is 1.6 per

cent. Bould (15) found a curvilinear relationship between the

foliar concentration of P, K, and Mg, and fruit yield.










The uptake of P by the strawberry plant has been reported

to increase with the increased supply of N (15). A similar re-

lationship between N and P was found by Anderson et al. (1).

There are very few reports regarding the mineral composi-

tion of strawberry fruits as affected by fertilizers. A negative

correlation between K content, and Ca and Na content of straw-

berry fruit was reported by Knight and Wallace (58). Bunemann

and Gruppe (22) showed that increased supply of N, P, K, Ca,

and Mg resulted in increased amounts of these nutrients in straw-

berry fruits. No direct K/Ca antagonism was found in the fruit,

but with increased Ca supply a reduction in the fruit Mg content

was observed. Bunemann (21) also reported that an antagonism

between K and Ca resulted in reduction of K accumulation in the

fruit with an increase in the Ca supply.
















MATERIALS AND METHODS

Two field experiments were conducted during the 1964-

1966 period at the Horticultural Unit near Gainesville, Florida.

Factorial experiments were designed to study the effects of the

source of potassium, and rates of potassium and nitrogen on

plant growth, fruit yield and quality of "Florida-90" straw-

berries.

Experiment I (1964-1965)

The first experiment was arranged in a 2 x 3 x 3 factorial

in a randomized block design with three replications. The soil

used was a Kanapaha fine sand with a pH of 6.1. The factors

studied were: sources of K- K2S04 and KC1; rates of K- 60,

120, and 180 pounds per acre; and rates of N- 60, 120, and 180

pounds per acre. Phosphorus was held constant at 70 pounds per

acre P. The different fertilizer mixtures were prepared using,

ammoniated superphosphate, K2S04, KC1, and ammonium nitrate.

One-half of the fertilizer was applied to each of the

8 x 25 foot plots, disked-in and beds 4 feet in width were pre-

pared leaving two feet on both sides as guard areas. The re-

maining half of the fertilizer was placed in a narrow band in

the center of the bed at a depth of 4 inches. A 0.4 acre inch

rain wet the beds to a depth of 8 inches before they were covered

with plastic. The beds were covered with black polyethylene

12










plastic film (1.5 mil thick and 4 feet wide) and plants were

set thru it using a hand trowel.

Experiment II (1965-1966)

The second experiment was arranged in a 3 x 3 x 3

factorial in a randomized block design with three replications.

The soil used was a Kanapaha fine sand with a pH of 6.3 due to

broadcasting of 2,000 pounds per acre dolomite. Soil levels

of K, Ca, and Mg were 88, 680, and 168 pounds per acre, re-

spectively. The plot size in this experiment was the same as

in Experiment I.

Factors in this experiment were: sources of K- K2SO4,

KNO3 and KC1; rates of K- 35, 90, and 145 pounds per acre; and

rates of N- 52, 100, and 148 pounds per acre. Phosphorus was

held constant at 70 pounds per acre P. The fertilizer mixtures

were prepared as described in Experiment I. In addition to

above treatments, a zero K and 100 pounds per acre N treatment

was included in the experiment but was not used in the statistical

analysis.

In this experiment the plant growth was measured in

terms of total fresh and dry weight of plant tops at the end

of the fruiting season (May 31, 1966). Plant tops were dried

at a temperature of 80 C in a forced draft oven for 48 hours.

Fruit size measurements were made at the March 25 and April 11

pickings, and the size was expressed as grams per fruit.









Cultural Practices and Fruit Yields

In both the experiments, to control insects and diseases,

tribasic copper plus zineb and malathion were used before the

fruiting. After the fruiting began, Kelthane was used to control

spider mites, and captain was used instead of tribasic copper and

zineb. Fruits were picked twice every week and the yields of

marketable and cull fruits were recorded. Yields were expressed

in terms of 12 pint flats per acre.

Fruit Sampling

Two fruit samples were collected in the 1964-1965 ex-

periment, one early (March 26) and the other later in the season

(April 16). Shear resistance, dry matter content, soluble

solids content, and total titratable acidity were determined

in fresh and stored fruits from both samples. Four samples were

collected in the 1965-1966 experiment. The sampling dates were

March 25, April 11, April 18, and May 2, 1966. Dry matter

content, soluble solids content, and total titratable acidity

in fresh and stored fruits were determined in March 25, April

11, and April 18 samples. Firmness measurements were not made

on the March 25 samples, whereas, only the firmness was measured

on May 2, 1966 samples.

Storage of Fruit

To study the effect of potassium source and rate of

potassium and nitrogen, on fruit quality after storage, fruits

from each sample were stored in well ventilated plastic pint

boxes. The storage temperature was.kept at 38 F. Relative

humidity in the storage room was about 85 per cent. The duration









of storage was eight days for samples in the 1964-1965 experi-

ment. In the 1965-1966 experiment, March 25, April 18, and May

2 samples were stored for eight days and the April 11 samples

were stored for four days.

Quality Measurements

Quality of both fresh and stored fruits was evaluated on

the basis of fruit firmness, dry matter content, soluble solids

content, and total titratable acidity in the fruit.

Fruit firmness was measured using an Allo Kramer shear

press model SP-12-IMP. A 2,500 pounds proving ring was used,

and the measurements were made at a thirty second stroke. A

standard shearing cell was employed. The size of the sample

was 100 g. Calyxes were removed before weighing the sample.

Fruits were arranged compactly across the slots in the bottom

of the cell. In the 1964-1965 experiment, due to a problem with

the recorder, only the shear resistance was measured. In the

1965-1966 experiment, however, both compression as well as shear

resistances were measured. Both compression and shear resistances

were read from the compression and shear peaks, respectively, and

were expressed in terms of pounds per 100 g fruit (49).

Samples used to determine the dry matter content of the

fruit were macerated in a Waring blender and then were dried in

a forced draft oven at a temperature of 80 C for 48 hours. The

dried samples of the fresh fruits were used for fruit tissue

analysis.

The soluble solids content of the fruit juice was measured

with a Bausch and Lomb juice refractometer. In the 1964-1965










experiment the juice was obtained from the samples used in the

firmness measurements. In the 1965-1966 experiment the juice

was obtained by freezing and thawing approximately 50 g fruit

in sealed poly-bags. This modification of the technique in the

second year made it possible to make the measurements at a later

date. The juice was brought to room temperature before making

the measurements.

Total titratable acidity was measured using a 10.0

ml aliquot from the juice extracted for the soluble solids

determinations. The measurements were made using a Fisher

automatic titrimeter Model 36. The titratable acidity was

expressed in terms of meq. NaOH required to titrate'100.0 ml

juice to a pH of 8.1 (5).

Foliar Sampling

Samples of fully developed foliage were collected for

foliar analysis as described by Ballinger and Mason (7), and

Kwong and Boynton (62). They were washed with a mild soap

solution and distilled water, and were dried at a temperature

of 80 C. Dried samples were ground through a 20 mesh screen

in a Wiley mill, and were stored in brown paper bags until

analyses were made. In the 1964-1965 experiment foliar samples

were collected on March 26 and April 16, 1965. In the 1965-1966

experiment four foliar samples were collected. The sampling

dates were January 17, March 17, April 18, and May 17, covering

most of the growing season. The January 17 samples were collected

at the early flowering and fruiting period, March 17 and April 18

samples were collected during late flowering and fruiting periods.










The May 17 samples were collected at the end of the fruiting

season.

Analytical Procedure

Both the foliage and the fruit samples were dry ashed,

and were analyzed for their K, Ca, and Mg contents (54). Total

N determinations were made using semimicro-Kjehldahl method (5).

A 0.1 g tissue sample was used to estimate the total N content.

K and Ca were determined by emission spectroscopy and Mg by

absorption spectroscopy. A Beckman DU flame spectrophotometer

was used at a wave length of 770 mp to detect K and at 554 my

to detect Ca. Determination of Mg were made colorimetrically

using thiazole yellow (8). The color complex was measured at

a wave length of 540 mp .

Statistical Analysis

The sum of squares for the calculation of the analysis

of variance were computed by the data processing laboratory of

the Agricultural Experiment Station at Gainesville. Table 2

shows the orthogonal comparisons made in the analysis of variance

of the 1964-1965 and 1965-1966 experiments.










Table 2. Orthogonal comparisons in Experiment I and Experiment II


Experiment I (1964-1965) Experiment II (1965-1966)

Sources of variation df Sources of variation df


Block
Source of potassium (K)
K2S04 vs. KCl

Rate of nitrogen (N)
Linear
Quadratic
Rate of potassium (K)
Linear
Quadratic
Source of K x rate of N
B x Cl
B x C2


Source
B x
B x


of K
Dl
D2


Rate of N x
Cl x D1
Cl x D2
C2 x Dl
C2 x D2
B x C x D
Error
Total


(A)

(B)


(Cl) 1
(C2) 1

(Dl) 1
(D2) 1

1
1


x rate of K


rate of K


Block
Source of potassium (K)
K2SO4 vs. KC1
K2SO4+KC1 vs. KNO3N
Rate of nitrogen (N)
Linear
Quadratic
Rate of potassium (K)
Linear
Quadratic
Source of K x rate of N
Bl x Cl
Bl x C2
B2 x Cl
B2 x C2
Source of K x rate of K
B1 x Dl
Bl x D2
B2 x D1
B2 x D2
Rate of N x rate of K
Cl x D1
Cl x DB
C2 x D1
C2 x D2
B x C x D
Error
Total


(A)


(Bl) 1
(B2) 1

(Cl) 1
(C2) 1


(Dl)
(D2)


- --
















RESULTS

Experiment I (1964-1965)

Fruit yield

Early and total yields of marketable and cull fruits

were not significantly affected by either rates of K and N or

source of K (Tables 3, 4). However, a trend for reduction in

the yield of marketable fruits with increased rates of K was

noted. The total yield of culls was significantly less in plots

where K2S04 was the K- source as compared to plots fertilized

with KC1.

Fresh and stored fruit quality

Firmness -- In this experiment only shear resistance of

the fruit was measured. The effect of treatments on the shear

resistance of fresh fruit is shown in Table 5. At the March 26

picking, treatment effects on the shear resistance were not

significant. However, there was a trend for the shear resistance

to be increased with increased rates of N and to be decreased

with increased rates of K. A trend for fruits to show a higher

shear resistance when the K- source was K2SO4 as compared with

KC1 was also noted. At the April 16 picking, a linear reduction

in the shear resistance of the fruit with an increase in the

K- rate was significant. This reduction in the shear resistance

was from 100.4 to 93.6 pounds per 100 g fruit as the K- rate was

increased from 60 to 180 pounds per acre. An interaction between

19












Table 3. Effect of potassium source and rate of potassium and nitrogen
on early yields of marketable and cull strawberries, 1965.

Rate Yield (12 pint flats per acre)
lb/acre Marketable Culls
N K K2SO4 (KC Mean K2SO4 KC1 Mean

60 60 54.2 45.9 50.0 4.4 4.0 4.2
120 50.9 34.5 42.7 3.4 3.1 3.2
180 59.0 34.1 46.5 5.4 2.2 3.8
Mean 54.7 38.2 46.4 4.4 3.1 3.7

120 60 64.8 56.3 60.5 4.2 3.6 3.9
120 32.5 35.2 33.9 4.3 3.4 3.8
180 37.3 37.2 37.2 4.4 4.0 4.2
Mean 44.9 42.9 43.9 4.3 3.6 3.9

180 60 43.5 59.8 51.6 3.3 4.9 4.1
120 33.4 68.3 50.8 4.3 4.3 4.3
180 49.6 41.7 45.6 6.4 6.3 6.3
Mean 42.1 56.6 49.3 4.7 5.2 4.9

60 54.2 54.0 54.1 4.0 4.2 4.1
120 38.9 46.0 42.4 4.0 3.6 3.8
180 48.6 37.7 43.1 5.4 4.2 4.8
Mean 47.2 45.9 46.5 4.4 4.0 4.2
Treatment effects not significant.











Table 4. Effect of potassium source and rate of potassium and nitrogen
on total yields of marketable and cull strawberries, 1965.


Rate Yield (12 pint flats per acre)
Ib/acre Marketable Culls
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 727.9 746.4 737.1 159.0 200.4 179.7
120 837.7 548.2 692.9 171.6 168.8 170.2
180 841.5 609.0 725.2 165.3 179.1 172.2
Mean 802.4 634.5 718.4 165.3 182.8 174.0

120 60 865.0 803.7 934.3 185.0 192.5 188.7
120 685.4 702.0 693.7 183.4 185.9 184.6
180 728.9 -714.1 721.5 146.4 189.0 167.7
Mean 759.8 739.8 749.8 171.6 189.2 180.4

180 60 743.6 676.6 710.1 146.4 189.0 167.7
120 589.3 960.0 774.6 141.3 235.1 188.2
180 679.0 678.1 678.5 168.3 186.7 177.5
Mean 670.7 771.6 721.1 154.2 201.1 177.6

60 788.8 742.2 760.5 164.6 191.4 178.4
120 704.1 736.7 720.4 165.4 196.6 181.0
180 749.8 667.1 708.4 160.0 184.9 172.4
Mean 744.2 715.3 729.7 163.7 191.0 177.3


Significant treatment effects:
Culls Mean of K2SO4 is less than

*Significant at 5% level of P.


mean of KCl'.










Table 5. Effect of potassium source and rate of potassium and nitrogen
on shear resistance of fresh strawberries from March 26 and April 16, 1965
pickings.

Rate Shear resistance (lb/100 g fruit)
Ib/acre- March 26 April 16
N K K2SO4 KC1 Mean K2S04 KCl Mean

60 60 120.7 109.7 115.1 95.0 98.3 96.7
120 123.3 104.0 113.7 99.0 95.0 97.0
180 115.3 109.7 112.5 88.3 104.3 96.3
Mean 119.8 107.8 113.8 94.1 99.2 96.7

120 60 124.7 118.3 121.5 102.7 104.0 103.3
120 123.0 116.0 119.5 97.3 86.0 91.7
180 106.0 102.0 104.0 99.3 90.3 94.8
Mean 117.9 112.1 115.0 99.8 93.4 96.6

180 60 118.0 109.3 113.4 98.3 104.0 101.2
120 118.0 123.7 120.8 -90.7 107.6 99.1
180 132.0 120.3 126.2 86.3 93.0 89.7
Mean 122.7 117.8 120.1 91.8 101.5 96.6

60 121.1 112.4 116.8 98.7 102.1 100.4
120 121.1 114.6 117.9 .95.7 96.2 95.9
180 117.8 110.7 114.2 91.3 95.9 93.6
Mean 120.0 112.6 116.3 95.6 98.1 96.8
Significant treatment effects:
April 16 K rate effect is linear*.
K2SO4 vs. KCl x N quadratic*.


*Significant at 5% level of P.









the source of K and N- rate was also significant. Fruits from

plots receiving K from KC1 were firmer than fruits from plots

receiving K from K2S04, when the N- rates were 60 and 180 pounds

per acre. However, at 120 pounds per acre rate of N, fruits from

plots receiving K2S04 were firmer as compared to those from plots

receiving KC1.

After eight days of storage at 38 F, the average shear

resistance of the fruits from the April 16 picking increased

from 96.8 to 113.9 pounds per 100 g fruit. Such an increase

was not found in the March 26 samples (Tables 5, 6).

An interaction between K- source and N- rate was

significant in stored samples from the March 26 picking. This

interaction was difficult to interpret. In stored samples from

the April 16 picking a quadratic effect of K- rate on the shear

resistance was significant. The shear resistance increased from

107.7 to 124.8 pounds per 100 g fruit, as the K- rate was increased

from 60 to 120 pounds per acre. A further increase in the K- rate

to 180 pounds per acre reduced the shear resistance to 113.3 pounds

per 100 g fruit. Other treatment effects were not significant.

Soluble solids -- Soluble solids content of fresh fruits

at two harvest dates is shown in Table 7. At the March 26 pick-

ing, a linear decrease in the fruit soluble solids content with

increased rates of K was significant. Soluble solids decreased

from 5.28 to 4.87 per cent as the K- rate was increased from 60

to 180 pounds per acre. A significant interaction between the

source of K and the rate of K showed that the linear reduction

in the soluble solids content of the fruit was greater when the










Table 6.
on shear
pickings


Effect of potassium source and rate of potassium and nitrogen
resistance of strawberries from March 26 and April 16, 1965
after eight days in storage.


Rate Shear resistance (lb/100/g fruit)
Ib/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 120.3 125.3 122.8 120.0 112.7 116.4
120 106.0 101.0 103.5 99.0 166.3 132.7
180 126.0 107.7 116.5 101.3 123.0 112.2
Mean 117.4 111.3 114.4 106.8 134.0 120.4

120 60 112.7 124.0 118.3 112.7 103.3 108.0
120 109.0 117.7 113.3 119.7 131.7 125.7
180 102.6 122.7 112.7 98.3 111.0 104.7
Mean 108.1 121.5 114.8 110.2 115.3 112.8

180 60 117.3 123.3 119.7 98.0 99.7 98.9
120 120.7 118.7 119.7 123.3 109.0 116.2
180 125.0 116.3 120.6 106.0 140.0 123.0
Mean 121.0 119.4 120.0 109.1 116.2 112.7

60 116.8 124.2 120.5 110.2 105.3 107.8
120 111.9 112.5 112.2 114.0 135.7 124.9
180 117.9 115.6 116.8 101.9 124.7 113.3
Mean 115.5 117.4 116.5 108.7 120.7 115.3


Significant effects:
March 26 K2SO4 vs. KC1
April 16 K rate effect


x N quadratic*.
is quadratic*.


*Significant at 5% level of P.










Table 7. Effect of potassium source and rate of
soluble solids content of fresh strawberries from
1965 pickings.


potassium and nitrogen on
March 26 and April 16,


Rate Soluble solids (per cent)
Ib/acre March 26 April 16
N K K2SO4 KCl Mean K2SO4 KC1 Mean

60 60 5.27 5.47 5.37 6.84 6.00 6.42
120 4.80 4.94 4.87 6.07 5.74 5.91
180 4.80 4.80 4.80 6.44 5.77 6.11
Mean 4.96 5.07 5.01 6.45 5.84 6.15

120 60 4.67 5.10 4.89 5.64 5.44 5.54
120 5.17 4.64 4.91 6.00 5.50 5.75
180 4.94 4.74 4.84 5.47 5.90 5.69
Mean 4.93 4.83 4.88 5.70 5.61 5.66

180 60 5.14 5.27 5.21 5.77 5.60 5.69
120 5.27 5.30 5.29 6.14 5.40 5.77
180 5.47 4.47 4.97 6.00 6.00 6.00
Mean 5.29 5.01 5.16 5.97 5.67 5.82

60 5.27 5.28 5.28 6.08 5.68 5.88
120 5.08 4.96 5.02 6.07 5.55 5.81
180 5.07 4.67 4.87 5.97 5.89 5.93
Mean 5.14 4.97 5.06 6.04 5.71 5.87
Significant treatment effects:
March 26 K rate effect is linear*.
K2SO4 vs. KC1 x K linear-.


*Significant at 5% level of P.










K- source was KC1. Treatment effects in the April 16 samples

were not significant.

After eight days of storage at 38 F, fruit soluble solids

content decreased from 5.06 to 4.98 per cent in the March 26

samples and from 5.87'to 5.83 per cent in the April 16 samples

(Tables 7, 8). The soluble solids content of stored fruits

harvested on March 26 was significantly greater when K2SO4 was

the source of K as compared to KC1 (Table 8). The main effect

of N- rate on soluble solids content of the stored fruit was

quadratic. However, a significant interaction between K- source

and rate of N occurred. Where K2S04 was the source of K, fruit

soluble solids increased linearly from 5.04 to 5.31 per cent with

increased N- rates from 60 to 180 pounds per acre. However,with

KC1 as the source of K, the soluble solids content in the fruit

was reduced from 4.88 to 4.42 per cent, with an increase in N-

rate from 60 to 120 pounds per acre, but increased to 5.13 per

cent at 180 pounds per acre N. An interaction between the rate

of N and the rate of K was also significant. At 60 pounds per

acre rate of N, the soluble solids content of the fruit increased

linearly from 4.89 to 5.02 per cent with increased rates of K.

However, at 120 and 180 pounds per acre rates of N, the K- rate

effect was quadratic with the lowest soluble solids content at

the 180 pounds per acre rate of K. In the April 16 samples,

treatment effects on the soluble solids content of stored fruits

were not significant.

Dry matter content -- Treatment effects on the dry matter

content of both fresh and stored fruit from the March 26 samples









Table 8. Effect of potassium source and rate of potassium and nitrogen
on soluble solids content of strawberries from March 26 and April 16, 1965
pickings after eight days in storage.

Rate Soluble solids (per cent)
lb/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

.60 60 4.67 5.10 4.89 6.10 5.60 5.85
120 5.17 4.77 4.97 5.70 5.83 5.77
180 5.27 4.77 5.02 6.13 5.83 5.98
Mean 5.04 4.88 4.96 5.98 5.75 5.87

120 60 5.00 4.94 4.97 5.80 5.23 5.52
120 5.37 4.67 5.02 5.90 5.73 5.82
180 4.90 3.64 4.27 5.97 6.30 6.14
Mean 5.09 4.42 4.76 5.89 5.75 5.82

180 60 5.40 5.07 5.24 5.70 6.00 5.85
120 5.54 4.94 5.24 5.97 5.33 5.65
180 5.00 5.40 5.20 6.00 5.77 5.89
Mean 5.31 5.13 5.22 5.89 5.70 5.79

60 5.02 5.04 5.03 5.87 5.61 5.74
120 5.36 4.79 5.08 5.86 5.63 5.75
180 5.06 4.60 4.83 6.03 5.97 6.00
Mean 5.15 4.81 4.98 5.92 5.74 5.83


Significant treatment effects:
March 26 Mean of K2SO4 is greater than
N rate effect is quadratic**.
K2SO4 vs. KC1 x N quadratic*.


mean of KC1**.
K rate effect is quadratic*.
N quadratic x K linear*.


*Significant at 5% level of P.
"*Significant at 1% level of P.










were not significant (Tables 9, 10). However, at the April 16

sampling, dry matter content of the fresh fruits was signifi-

cantly affected by an interaction between the source of K and

rates of K (Table 9). Where KC1 was the source of K, the dry

matter content of the fruit increased linearly with increased

rates of IK. Whereas, with K2SO4 as the source of K, rate of K

had less effect. In the stored fruits from the April 16 picking,

an interaction between the source of K and N- rate was also

significant (Table 10). With increased rate of N, the dry matter

content of stored fruits was reduced with both sources of K.

The reduction was greater when the K- source was X2SO4 as compared

to KC1. There was also a slight trend towards higher dry matter

content of fruit with increased rates of K and a declining trend

with increased rates of N in both fresh and the stored samples

from both, March 26 and April 16 pickings.

Total titratable acidity -- Data in Table 11 show that

treatment effects on the total titratable acidity of fresh fruits

from the March 26 picking were not significant. However, samples

of fresh fruits from the April 16 picking showed a highly sig-

nificant linear increase in the total titratable acidity with

increased rates of K. This increase was from 15.68 to 17.01

meq. NaOH required to titrate a 100 ml sample of fruit juice,

as the K- rate increased from 60 to 180 pounds per acre. In-

creased rates of N from 60 to 180 pounds per acre resulted in

a significant linear reduction in the total titratable acidity

of the fresh fruits. An interaction between the rate of K and

rate of N was also significant. The main effect of increased









Table 9. Effect of potassium source and rate of potassium and nitrogen
on dry matter content of fresh strawberries from March 26 and April 16,
1965 pickings.

Rate Dry matter (per cent)
lb/acre March 26 A pril 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 8.73 10.00 9.37 9.94 9.93 9.96
120 8.52 9.43 8.98 10.05 11.56 10.81
180 8.77 8.73 8.75 9.82 9.30 9.56
Mean 8.67 9.39 9.03 9.94 10.26 10.11

120 60 8.01 8.05 8.03 9.93 9.60 9.76
120 8.21 10.27 9.14 6.66 9.49 8.08
180 8.52 7.77 8.15 10.24 10.21 10.23
Mean 8.25 8.69 8.47 8.94 9.77 9.36

180 60 8.94 8.42 9.18 9.63 9.37 9.50
120 9.15 8.94 9.05 9.54 8.97 9.26
180 8.60 8.79 8.69 9.41 9.86 9.64
Mean 8.89 8.72 8.81 9.53 9.40 9.47

60 8.56 8.82 8.69 9.83 9.63 9.73
120 8.63 9.55 9.09 8.75 9.99 9.37
180 8.63 9.54 9.09 9.82 9.79 9.81
Mean 8.61 9.30 8.96 9.47 9.80 9.64
Significant treatment effects:
April 16 K2SO4 vs. KC1 x K linear*.


*Significant at 5% level of P.











Table 10. Effect of potassium source and rate of potassium and nitrogen
on dry matter content of strawberries from March 26 and April 16, 1965
pickings after eight days in storage.

Rate Dry matter (per cent)
Ib/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 11.42 9.26 10.34 10.34 12.47 11.41
120 9.01 9.16 9.09 10.64 12.69 11.67
180 9.01 8.90 8.96 16.67 11.46 14.06
Mean 9.81 9.11 9.46 12.91 12.21 12.38

120 60 8.69 8.92 8.80 10.73 10.79 10.76
120 9.09 11.62 10.36 11.33 9.62 10.47
180 9.35 8.99 8.67 11.29 10.73 11.01
Mean 9.04 9.84 9.28 11.12 11.38 10.75

180 60 -8.37 11.07 9.72 10.64 10.16 10.40
120 11.24 7.89 9.57 9.76 11.55 10.66
180 8.66 8.41 8.54 11.08 11.13 11.11
Mean 9.42 9.12 9.28 10.49 10.95 10.72

60 9.49 9.75 9.62 10.60 11.14 10.87
120 9.78 9.56 9.67 10.58 11.29 10.93
180 8.67 8.77 8.72 -13.01 11.11 12.06
Mean 9.31 9.36 9.34 11.39 11.18 11.29
Significant treatment effects:
April 16 K2SO4 vs. KC1 x N linear-.


*Significant at 5% level of P.









Table 11. Effect of potassium source and rate of potassium and nitrogen
on total titratable acidity of fresh strawberries from March 26 and April
16, 1965 pickings.

Rate Total titratable acidity (meq.NaOH)
lb/acre March 26 April 16
N K K2SO4 KCl Mean K2SO4 KC1 Mean

60 60 17.77 20.69 19.23 18.12 15.94 17.03
120 18.15 17.21 17.68 17.76 16.10 16.93
180 17.24 17.68 17.46 17.09 17.39 17.24
Mean 17.72 18.53 18.12 17.66 16.45 17.07

120 60 12.12 16.23 14.18 15.29 14.61 14.95
120 18.08 20.36 19.22 16.64 15.08 15.86
180 16.09 16.69 16.39 17.25 16.54 16.92
Mean 15.43 17.76 16.59 16.39 15.42 15.91

180 60 16.69 16.32 16.51 15.42 14.65 15.04
120 18.62 17.52 18.07 17.12 14.37 15.75
180 17.07 17.66 17.37 17.25 16.51 16.88
Mean 17.46 17.17 17.32 16.59 15.18 15.89

60 15.53 17.75 16.64 16.28 15.07 15.68
120 18.28 18.36 18.32 17.17 15.18 16.18
180 16.80 17.34 17.07 17.19 16.83 17.01
Mean 16.87 17.82 17.34 16.88 15.69 16.29
Significant treatment effects:
April 16 Mean of K2SO4 is greater than mean of KC1*-.
N rate effect is linear**. K rate effect is linear**.
N linear x K linear*. K2SO4 vs. KC1 x K quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.









rate of N was a linear reduction in the titratable acidity of

fruit. However, as the K- rate increased from 60 to 180 pounds

per acre, the reduction in the total titratable acidity due to

increased rates of N, was less. At the 60 pounds per acre rate

of potassium the total titratable acidity was reduced by 2.99

meq. with an increase in the N- rate from 60 to 180 pounds per

acre. At the 120 pounds per acre rate of K, the total titratable

acidity was reduced by 1.18 meq., and at 180 pounds per acre

rate of K, the reduction was only by 0.36 meq. This shows that

the effect of N- rate in reducing the total titratable acidity

of the fruit can be compensated by increasing the K- rate.

Plants fertilized with K2S04 produced fruits with higher

total titratable acidity than those where the K- source was KC1.

An interaction between K- source and rate of K was also sig-

nificant. When the K- source was K2SO4, increased rates of K

from 60 to 180 pounds per acre resulted in the maximum increase

in the total titratable acidity of the fresh fruits. However,

with KC1 as the source of K, increased supply of K from 60 to 180

pounds per acre had little effect on the total titratable acidity,

but a further increase in the K- rate to 180 pounds per acre re-

sulted in a large increase in the total titratable acidity.

In general, the total titratable acidity of fruits was

reduced during storage for eight days at 38 F. These reductions

were 2.67 meq. in the March 26 and 1.57 meq. in the April 16

samples (Tables 11, 12).

The source of K significantly affected the total titrat-

able acidity of stored fruits from both the March 26 and April 16










Table 12. Effect of potassium source and rate of potassium and nitrogen on
total titratable acidity of strawberries from March 26 and April 16, 1965
pickings after eight days in storage.


Rate Total titratable acidity (meq. NaOH)
lb/acre March 26 April 16
N K K2S04 KC1 Mean K2SO4 KC1 Mean

60 60 14.23 13.12 13.62 15.15 14.89 15.02
120 14.94 15.08 15.01 16.68 14.60 15.64
180 15.86 14.94 15.40 17.15 15.09 16.12
Mean 15.01 14.38 14.68 16.33 14.87 15.59

120 60 15.43 14.33 14.88 14.94 11.54 13.24
120 15.64 13.66 14.65 15.37 14.40 14.88
180 14.40 13.89 14.14 15.41 14.14 14.77
Mean 15.15 13.96 14.56 15.24 13.36 14.29

180 60 16.29 15.02 15.66 13.57 14.01 13.79
120 13.42 14.06 13.74 14.81 12.97 13.89
180 15.32 14.47 14.89 16.72 13.58 15.15
Mean 15.01 14.51 14.76 15.03 13.52 14.28

60 15.31 14.16 14.73 14.55 13.48 14.02
120 14.67 14.27 14.47 15.62 13.99 14.80
180 15.19 14.43 14.81 16.43 14.27 15.35
Mean 15.06 14.29 14.67 15.53 13.91 14.72


Significant treatment effects:
March 26 Mean of K2SO4 is greater
April 16 Mean of K2SO4 is greater
K rate effect is linear*.

*Significant at 5% level of P.
**Significant at 1% level of P.


than mean of KC**'.
than mean of KC1*.










samples (Table 12). In both cases the total titratable acidity

was higher where the K- source was K2S04 as compared to KC1.

The differences were 0.77 meq. in the March 26 samples and 1.62

meq. in the April 16 samples. In the stored fruit from April 16

samples, a significant linear increase in the total titratable

acidity with increased rates of K was also found. Titratable

acidity increased from 14.02 to 15.35 meq. with an increase in

the rate of K from 60 to 180 pounds per acre.

Fruit tissue composition

Total nitrogen -- Total N analyses of the fresh fruits

at the March 26 and April 16 pickings are shown in Table 13.

Total N content of fruit tissue at both samplings increased

linearly with increased rates of N. In the March 26 samples,

this significant increase was from 1.25 to 1.55 per cent as N-

rates were increased from 60 to 180 pounds per acre.

In the April 16 sample a significant interaction be-

tween the source of K and N- rate occurred. Where K2S04 was

the source of K, fruit N content increased with increased rates

of N. But with KC1 as the source of K, fruit N content declined

linearly with an increase in the N- rate.

Potassium -- Effect of treatments on the K content of

fruits harvested on March 26 and April 16 are given in Table 14.

An interaction between the source of K and'rate of N was sig-

nificant at the March 26 sampling. Where K2SO4 was the source

of K, the K content of the fruit increased with an increase in

the rates of N. Also there was a trend for a linear increase in

the fruit K level with increased rates of K. In the April 16










Table 13. Effect of potassium source and rate of potassium and nitrogen
on total nitrogen content of strawberry fruits from March 26 and April 16,
1965 pickings.

Rate Total nitrogen (per cent)
Ib/acre March 26 April 16
N K K2S04 KC1 Mean K2SO4 KC1 Mean

60 60 1.29 1.30 1.29 1.45 1.26 1.36
120 1.22 1.35 1.28 1.34 1.77 1.55
180 1.37 1.01 1.19 1.28 1.66 1.47
Mean 1.29 1.22 1.25 1.36 1.56 1.46

120 60 1.36 1.13 1.25 1.18 1.12 1.15
120 1.25 1.74 1.49 1.34 1.62 1.48
180 1.54 1.46 1.50 1.33 1.52 1.43
Mean 1.38 1.44 1.41 1.28 1.42 1.35

180 60 1.55 1.53 1.54 1.66 1.53 1.59
120 1.63 1.25 1.44 1.39 1.27 1.33
180 1.44 1.91 1.67 1.49 1.33 1.41
Mean 1.54 1.56 1.55 1.51 1.38 1.44

60 1.40 1.32 1.36 1.43 1.30 1.37
120 1.36 1.44 1.40 1.36 1.55 1.46
180 1.45 1.46 1.46 1.37 1.50 1.44
Mean 1.40 1.41 1.41 1.38 1.45 1.42
Significant treatment effects:
March 26 N rate effect is linear-*.
April 16 N rate effect is linear*.
K2SO4 vs. KC1 x N quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.










Table 14. Effect of potassium source and rate of potassium and nitrogen
on potassium content of strawberry fruits from March 26 and April 16,
1965 pickings.

Rate Potassium content (per cent)
Ib/acre March 26 April 16
N K K2S04 KC1 Mean K2SO4 KC1 Mean

60 60 1.54 1.69 1.62 1.61 1.57 1.59
120 1.59 1.80 1.69 1.86 1.57 1.71
180 1.61 1.69 1.65 1.51 1.87 1.69
Mean 1.58 1.73 1.66 1.66 1.67 1.67

120 60 1.68 1.56 1.08 1.42 1.61 1.52
120 1.69 1.35 1.52 1.69 1.78 1.74
180 1.78 1.61 1.69 1.70 1.88 1.79
Mean 1.72 1.51 1.62 1.60 1.75 1.68

180 60 1.59 1.53 1.56 1.59 1.54 1.57
120 1.64 1.52 1.58 -1.37 1.58 1.47
180 1.74 1.49 1.62 1.91 1.84 1.87
Mean 1.66 1.51 1.59 1.62 1.65 1.63

60 1.60 1.59 1.59 1.54 1.57 1.55
120 1.64 1.56 1.60 1.64 1.64 1.64
180 1.71 1.60 1.66 1.71 1.86 1.78
Mean 1.65 1.58 1.62 -1.63 1.69 1.66
Significant treatment effects:
March 26 K2SO4 vs. KC1 x N linear*.
April 16 K rate effect is linear**.
N linear x K quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.










sample however, this effect of K- rate on fruit K content was

significant. The fruit K content increased from 1.55 to 1.78

per cent with an increase in the rate of K from 60 to 180 pounds

per acre. Due to a significant interaction between the rate of

N and rate of K, increased rates of N resulted in little increase

in the fruit K content where either 60 or 120 pounds per acre

K was applied. However,at 180 pounds per acre K- rate, fruit

K content increased linearly from 1.69 to 1.87 per cent with an

increase in the rate of N from 60 to 180 pounds per acre.

Calcium -- Fruit Ca contents at the March 26 sampling

were significantly higher where KC1 was the source of K (Table

15). The fruit Ca contents were 0.119 per cent with K2SO4 and

0.173 per cent with the KCl source. In the April 16 sample, a

trend for this difference in the K- source effect was also found.

An interaction between the source of K and N- rate was signifi-

cant at the April 16 sampling. When K2S04 was the source of K,

increased rates N resulted in a reduction in fruit Ca levels.

However, where KC1 was the source of K, fruit Ca content in-

creased with increased rates of N.

Magnesium -- Treatment effects on the fruit Mg content

were not significant at the March 26 sampling (Table 16). How-

ever, in April 16 samples an interaction between the source of

K and the rate of N was significant. At the 60 and 180 pounds

per acre rate of N, fruit Mg contents were greater where the K-

source was K2SO4. At the 120 pounds per acre rate of N however,

the fruit Mg content was highest with KC1 as the source of K.










Table 15. Effect of potassium source and rate of potassium and nitrogen
on calcium content of strawberry fruits from March 26 and April 16, 1965
pickings.

Rate Calcium content (per cent)
Ib/acre March 26 April 16
N K K2SO4 KCI Mean K2S04 KCl Mean

60 60 0.138 0.144 0.141 0.143 0.186 0.164
120 0.108 0.193 0.151 0.171 0.175 0.173
180 0.111 0.168 0.140 0.224 0.182 0.203
Mean 0.119 0.168 0.143 0.179 0.181 0.180

120 60 0.123 0.175 0.149 0.141 0.172 0.157
120 0.097 0.173 0.135 0.113 0.194 0.153
180 0.105 0.179 0.142 0.149 0.178 0.163
Mean 0.108 0.176 0.142 0.134 0.181 0.157

180 60 0.116 0.187 0.152 0.155 0.192 0.174
120 0.128 0.182 0.155 0.159 0.187 0.173
180 0.149 0.162 0.156 0.170 0.185 0.178
Mean 0.131 0.177 0.154 0.161 0.188 0.175

60 0.126 0.168 0.147 0.146 0.183 0.164
120 0.111 0.183 0.147 0.148 0.185 0.166
180 0.122 0.169 0.146 0.181 0,182 0.181
Mean 0.119 0.173 0.146 0.158 0.183 0.171


Significant treatment effects:
March 26 Mean of K2SO4 is less than me
April 16 N rate effect is quadratic*.
K2SO4 vs. KC1 x N quadratic*.


an of KC1**.


*Significant at 5% level of P.
**Significant at 1% level of P.











Table 16. Effect of potassium source and rate of potassium
on magnesium content of strawberry fruits from March 26 and
1965 pickings.


and nitrogen
April 16,


Rate Magnesium content (per cent x 10-")
Ib/acre March 26 April 16
N K K2SO4 KCI Mean K2SO4 KC1 Mean

60 60 0.31 0.34 0.33 0.73 0.73 0.73
120 0.38 0.62 0.50 1.13 0.70 0.91
180 0.38 0.79 0.59 1.10 0.54 0.82
Mean 0.36 0.58 0.47 0.99 0.66 0.83

120 60 0.34 0.35 0.35 0.48 0.89 0.69
120 0.36 0.31 0.34 0.79 0.69 0.74
180 0.36 0.34 0.35 0.64 0.61 0.63
Mean 0.35 0.33 0.34 0.64 0.73 0.69

180 60 0.33 0.33 0.33 0.64 0.63 0.78
120 0.34 0.33 0.33 0.79 0.54 0.67
180 0.34 0.41 0.37 0.63 0.76 0.69
Mean 0.34 0.36 0.35 0.78 0.64 0.71

60 0.33 0.34 0.33 0.71 0.75 0.73
120 0.36 0.42 0.39 0.90 0.64 0.77
180 0.36 0.51 0.44 0.79 0.64 0.72
Mean 0.35 0.42 0.38 0.80 0.68 0.74
Significant treatment effects:
April 16 K2SO4 vs. KC1 x N quadratic*.


*Significant at 5% level of P.









Foliar composition

Total nitrogen -- Data in Table 17 show that, in March

26 samples, the foliar N levels were significantly increased

from 3.35 to 3.57 per cent with an increase in the rate of N

from 60 to 120 pounds per acre. A further increase in the N

supply reduced the foliar N level to 3.51 per cent. Foliar N

levels increased from 2.77 to 3.07 per cent as the rate of N

was increased from 60 to 180 pounds per acre. A significant

interaction between the source of K and the rate of K showed

that this linear increase was greater when the K- source was

K2SO4 as compared to KC1.

Potassium -- Foliar K levels were increased significantly

by applications of K at both sampling dates (Table 18). The

increases were linear at both samplings and were from 1.81 to

2.05 per cent K at March 26, and from 1.85 to 2.54 per cent K

at April 16 sampling, as the rate of K was increased from 60 to

180 pounds per acre. An increase in the rate of N from 60 to

120 pounds per acre also resulted in a significant increase in

the leaf K content in the March 26 samples. This increase was

from 1.82 to 2.05 per cent K. A further increase in the N-

rate resulted in a reduction to 1.95 per cent foliar K.

An interaction between K- source and K- rate was signifi-

cant at the April 16 sampling. Where the K- source was K2S04,

the foliar K content increased to a higher level as the K- rate

was increased than where the K- source was KC1. Due to a sig-

nificant interaction between the rate of N and rate of K, the

foliar K- content was not influenced by increased rates of N,









Table 17. Effect of potassium source and rate of potassium and nitrogen
on total nitrogen content of strawberry foliage on March 26 and April 16,
1965.

Rate Total nitrogen (per cent)
Ib/acre March 26 April 16
N K K2SO4 KC1 Mean K2S04 KCl Mean

60 60 3.23 3.45 3.34 2.73 2.76 2.74
120 3.35 3.57 3.46 2.90 2.96 2.93
180 3.20 3.32 3.26 2.55 2.76 2.66
Mean 3.26 3.44 3.35 2.72 2.83 2.77

120 60 3.44 3.64 3.54 2.84 2.84 2.84
120 3.61 3.50 3.56 2.98 2.79 2.88
180 3.62 3.62 3.62 3.04 2.94 2.99
Mean 3.56 3.59 3.57 2.95 2.86 2.90

180 60 3.61 3.61 3.61 3.23 3.17 3.20
120 3.20 3.56 3.38 3.01 2.89 2.95
180 3.62 3.43 3.53 3.28 2.87 3.08
Mean 3.48 3.53 3.51 3.17 2.97 3.07

60 3.43 3.57 3.50 2.93 2.92 2.92
120 3.39 3.54 3.47 2.96 2.88 2.92
180 3.48 3.46 3.47 2.96 2.86 2.91
Mean 3.43 3.52 3.48 2.95 2.89 2.92
Significant treatment effects:
March 26 N rate effect is quadratic*.
April 16 N rate effect is linears-.
K2SO4 vs. KCI x N linear-.


*Significant at 5% level of P.









Table 18. Effect of potassium source and rate of potassium and nitrogen
on potassium content of strawberry foliage on March 26 and April 16, 1965.

Rate Potassium content(per cent)
Ib/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 1.71 1.78 1.75 1.87 1.96 1.91
120 1.81 1.95 1.88 2.25 1.99 2.12
180 1.72 1.91 1.82 2.70 2.49 2.59
Mean 1.75 1.88 1.82 2.27 2.15 2.21

120 60 1.95 1.78 1.87 1.88 1.69 1.79
120 2.00 1.96 1.98 2.66 2.34 2.50
180 2.51 2.11 2.31 2.70 2.57 2.64
Mean 2.15 1.95 2.05 2.41 2.20 2.31

180 60 1.85 1.81 1.83 1.91 1.83 1.87
120 2.06 1.94 2.00 1.84 2.07 1.96
180 2.05 2.10 2.03 2.82 1.95 2.38
Mean 1.99 1.92 1.95 2.19 1.95 2.07

60 1.84 1.79 1.81 1.88 1.83 1.85
120 1.96 1.95 1.95 2.25 2.13 2.19
180 2.09 2.01 2.05 2.74 2.34 2.54
Mean 1.96 1.92 1.94 2.29 2.10 2.19
Significant treatment effects:


March 26 -

April 16 -


N rate effect is quadratic*.
K rate effect is linear-*.
K rate effect is linear''.
K2SO4 vs. KC1 x K linear*.
N quadratic x K quadratic"*.


*Significant at 5% level of P.
**Significant at 1% level of P.










where the K- rate was 60 pounds per acre. However, where the K-

rate was higher, an increase in the rate of N from 60 to 120

po-nds per acre resulted in a subs-tntial increase i'n te foliA\

K content. A further increase in the N- rate to 180 pounds per

acre resulted in a reduced K level in the foliage in April 16

samples.

Calcium -- Foliar Ca contents in the March 26 samples

vierei not significantlyy influenced by treatments (Table 19).

However a trend for the foliar Ca level to decline with an in-

crease in the K- rate was noted. This trend became highly

significant at the April 16 sampling. The Ca content of the

foliage decreased from 1.27 to 1.13 per cent as the rate of K

was increased from 60 to 180 pounds per acre. An interaction

between the source of K and N- rate was also significant at the

April 16 sampling. Where K2SO4 was the K- source, foliar levels

of Ca were reduced from 1.27 per cent to 1.06 per cent, as the N-

rate was increased from 60 to 180 pounds per acre. But where

KCI was the K- source, foliar Ca levels increased from 1.24

per cent to 1.27 per cent in response to increased rates of N.

The Ca content of the foliage in April 16 samples were consider-

ably greater than that in the March 26 samples.

Magnesium -- At the March 26 sampling a significant linear

reduction in the Mg content of strawberry foliage occurred with an

increase in the supply of both N and K (Table 20). A similar

linear decline in the foliar Mg levels with increased K rates

was also significant at the April 16 sampling. The Mg content

was reduced from 0.328 per cent to 0.313 per cent as the K- rate










Table 19.
on calcium


Effect of potassium source and rate of potassium and nitrogen
content of strawberry foliage on March 26 and April 16, 1965.


Rate Calcium content (per cent)
lb/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 0.841 0.737 0.789 1.41 1.30 1.35
120 0.794 0.622 0.708 1.19 1.20 1.19
180 0.598 0.704 0.651 1.20 1.21 1.21
Mean 0.744 0.687 0.716 1.27 1.24 1.25

120 60 0.637 0.647 0.642 1.36 1.29 1.33
120 0.645 0.641 0.643 1.08 1.23 1.16
180 0.408 0.621 0.515 1.02 1.10 1.06
Mean 0.563 0.636 0.599 1.15 1.21 1.18

180 60 0.671 0.753 0.712 1.11 1.20 1.16
120 0.719 0.750 0.734 1.06 1.31 1.19
180 0.760 0.807 0.784 .1.00 1.31 1.15
Mean 0.717 0.770 0.743 1.06 1.27 1.16

60 0.716 0.712 0.714 1.29 1.26 1.27
120 0.719 0.671 0.695 1.11 1.23 1.17
180 0.588 0.711 0.649 1.07 1.20 1.13
Mean 0.674 0.698 0.686 1.16 1.23 1.19
Significant treatment effects:
April 16 K rate effect is linear'*.
K2SO4 vs. KC1 x N linear*.


*Significant at 5% level of P.
**Significant at 1% level of P.









Table 20. Effect of potassium source and rate of potassium and nitrogen
on magnesium content of strawberry foliage on March 26 and April 16, 1965.

Rate Magnesium content (per cent)
Ib/acre March 26 April 16
N K K2SO4 KC1 Mean K2SO4 KC1 Mean

60 60 0.377 0.397 0.387 0.332 0.328 0.330
120 0.444 0.352 0.398 0.404 0.291 0.348
180 0.260 0.401 0.331 0.250 0.342 0.296
Mean 0.360 0.383 0.371 0.329 0.320 0.325

120 60 0.388 0.410 0.399 0.374 0.437 0.406
120 0.431 0.352 0.391 0.517 0.383 0.450
180 0.236 0.320 0.278 0.565 0.244 0.405
Mean 0.352 0.360 0.356 0.485 0.355 0.420

180 60 0.306 0.333 0.319 0.221 0.276 0.249
120 0.276 0.305 0.290 0.279 0.349 0.314
180 0.362 0.304 0.333 0.206 0.269 0.238
Mean 0.315 0.314 0.315 0.235 0.298 0.266

60 0.357 0.380 0.368 0.309 0.347 0.328
120 0.384 0.336 0.360 0.400 .0.341 0.371
180 0.286 0.342 0.314 0.340 0.285 0.313
Mean 0.342 0.353 0.347 0.349 0.324 0.337


Significant treatment effects:
March 26 N rate effect is linear*.
K rate effect is linear*.
April 16 Mean of K2SO4 is greater than mean
K rate effect is linear*.
N quadratic x K linear.


of KCI*.


*Significant at 5% level of P.










was increased from 60 to 180 pounds per acre. In the April 16

sample an interaction between the rate of N and the rate of K

was also significant. The foliar Mg content was highest when

the rates of N and K were 120 pounds per acre. A further in-

crease in the rate of either N or K resulted in a reduction in

the foliar Mg content. The Mg level in the foliage was sig-

nificantly greater when the source of K was K2SO4 as compared

with KC1. The Mg levels were 0.349 per cent with K2SO4 and 0.324

per cent with KC1.

Experiment II (1965-1966)

Fruit yield

The early yields of marketable and cull fruits are shown

in Table 21. The yields of marketable fruits were significantly

reduced from 293.0 flats per acre to 255.3 flats per acre with

an increase in the K- rate from 35 to 145 pounds per acre.

Furthermore, it should be noted that the early yield of marketable

fruits from plots not receiving applied K were very similar to

the average of yields from plots fertilized with K. An inter-

action between the source of K and N- rate was significant.

When K2SO4 was the source of K, the maximum yield of 295.6 flats

per acre was obtained at the 52 pounds per acre rate of N.

Whereas, with KC1 and KNO3 as the source of K, 100 pounds per

acre N were required to obtain the maximum yield of 284.0 and

300.3 flats per acre respectively. A significant interaction

between the source of K and rate of K showed that, as the rate

of K increased, the early yield of culls increased where the K-

source was KC1, but decreased where the K- source was K2SO4.








Table 21. Effect of potassium source and rate of potassium and nitrogen on early
yields of marketable and cull strawberries, 1966.

Rate Yield (12 pint flats per acre)
Ib/acre Marketable Culls
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 307.0 290.0 306.0 301.0 62.0 80.0 79.0 73.7
90 311.0 240.0 267.0 272.7 78.0 67.0 79.0 74.7
145 269.0 262.0 238.0 256.3 72.0 75.0 71.0 72.7
Mean 295.6 264.0 270.3 276.6 70.7 74.0 76.3 73.7

100 35 299.0 324.0 272.0 298.3 81.0 80.0 65.0 75.3
90 261.0 308.0 303.0 290.7 71.0 84.0 76.0 77.0
145 236.0 220.0 326.0 260.7 64.0 64.0 79.0 69.0
Mean 265.3 284.0 300.3 283.2 72.0 76.0 73.3 73.8

148 35 305.0 282.0 251.0 279.3 67.0 72.0 64.0 67.7
90 299.0 320.0 255.0 291.3 98.0 82.0 64.0 81.3
145 253.0 237.0 254.0 248.0 64.0 66.0 78.0 69.3
Mean 285.7 279.7 253.3 272.9 76.3 73.3 68.7 72.8

35 304.0 299.0 276.0 293.0 70.0 77.0 69.0 72.0
90 290.0 289.0 275.0 284.7 82.0 78.0 73.0 77.7
145 253.0 240.0 273.0 255.3 67.0 68.0 76.0 70.3
Mean 282.3 276.0 274.7 277.7 73.0 74.3 72.6 73.3
100 0 276.0 72.0
Significant treatment effects:
Marketable K rate effect is linear**.


Culls


K2S04 vs. KC1 x N quadratic*.
- K2SO4 vs. KC1 x K lineari-.


*Significant at 5% level of P.
**Significant at 1% level of P.










The total yields of marketable fruits as well as culls

were not significantly affected by treatment (Table 22). With

increased rates of K, the yield of marketable fruit tended to

be reduced. Also K2S04 as the source of K appeared to produce

higher total yield of marketable fruits as compared to KNO3 and

KC1. However, differences in the yields due to the various K-

rates and K- source were less than 4 per cent. The mean total

yield of marketable fruits from plots not receiving K was 17.8

per cent lower than the average yield from plots where K was

applied, whereas, that of culls was 21.0 per cent lower.

Figures 1 and 2 illustrate the marketable yields of

fruits from the individual pickings as affected by the rate of

K and rate of N respectively. Figure 1 shows that early in the

season K- rates did not produce higher yield of marketable fruits

as compared to plots where K was not applied. Moreover, it

clearly shows a linear decline in the early yields of marketable

fruits as the rate of K increased from 35 to 145 pounds per acre.

As the season progressed, however, the yields of marketable

fruits from plots not receiving K were consistently lower than

average of yields from plots receiving K. The differences in

the yield due to rate of potassium were very small late in the

season, and at May 2 and May 5 pickings, yields appeared to

increase with increased rates of K.

The yield curves for N- rate (Figure 2) show that over

the entire fruiting period, N- rates did not affect the yield

of marketable fruits to any great extent. It should be noted

that in Experiment II the total fruit production was considerably







Table 22. Effect of potassium source and rate of potassium and nitrogen on total
yields of marketable and cull strawberries, 1966.

Rate Yield (12 pint flats per acre)
Ib/acre Marketable Culls
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 1016.0 1161.0 1086.0 1087.6 312.0 422.0 332.0 355.3
90 1160.0 946.0 1038.0 1048.0 406.0 392.0 350.0 382.7
145 910.0 1038.0 914.0 954.0 344.0 352.0 308.0 334.7
Mean 1028.7 1048.3 1012.7 1029.8 354.0 388.7 330.0 357.6

100 35 1194.0 1079.0 1011.0 1094.7 430.0 398.0 282.0 370.0
90 1085.0 1064.0 1076.0 1074.0 348.0 429.0 340.0 372.3
145 1147.0 890.0 1204.0 1080.3 377.0 298.0 398.0 357.6
Mean 1142.0 1011.0 1097.0 1083.3 385.0 375.0 340.0 366.6

148 35 1093.0 955.0 1076.0 1041.3 354.0 289.0 332.0 325.0
90 1081.0 1174.0 968.0 1074.3 361.0 410.0 295.0 355.3
145 1030.0 1048.0 1177.0 1085.0 327.0 332.0 362.0 340.3
Mean 1068.0 1059.0 1073.7 1066.9 347.3 343.6 329.7 340.2

35 1101.0 1065.0 1058.0 1075.0 365.0 370.0 315.0 350.0
90 1109.0 1061.0 1027.0 1066.0 372.0 410.0 328.0 370.0
145 1029.0 992.0 1098.0 1039.0 349.0 327.0 356.0 344.0
Mean 1079.6 1039.4 1061.1 1059.7 362.0 369.0 333.0 354.7
100 0 870.0 280.0
Treatment effects not significant.












0 lb/A
35 lb/A"- "
90 lb/A --*--*--
145 lb/A --


Jan Mar Apr.
25 25 29 1 5 7 11 14 18 21
Date of Picking


May
25 28 2 5


Figure 1. Yield of fruit (g per plot) at individual
pickings in the 1966 fruiting season as affected by
various rates of K.














52 lb/A- -
10 0 lb/A --*
148 lb/A ---0-


Jan. Mar Apr.
25 25 29 1 5 7 11 14 18 21

Date of Picking


May
25 28 2 5


Figure 2. Yield of fruit (g per plot) at individual
pickings in the 1966 fruiting season as affected by
various rates of N.


800




700



600


500


400


300


200


100










greater than in Experiment I (Tables 4, 22). Also the rates of

both N and K were lower in Experiment II as compared with those

in Experiment I.

Fruit size

The effect of treatments on fruit size is shown in Table

23. In general the fruit size was reduced considerably as the

fruiting season progressed from the March 25 to the April 11

picking. The main effect of K- rate on fruit size at the March

26 picking was a linear reduction with increased rates of K. A

similar trend occurred at the April 11 picking. At the April 11

picking an interaction between the source of K and rate of N

was significant. Where the source of K was K2SO4 or KNO3, the

largest fruits were produced with an application of 100 pounds

per acre N. With the KC1 source, however, the smallest fruits

were produced at the 100 pounds per acre rate of N.

At the March 25 picking the fruit size from plots which

did not receive K was equal to the average fruit size from plots

fertilized with K. At the April 11 picking,however, the fruit

size tended to be greater in plots not receiving K.

Plant growth

Fresh and dry weights of plant tops at the end of the

1966 fruiting season are given in Table 24. Main effects of K-

source and rates of K and N on plant fresh weight were not sig-

nificant. An interaction between K- source and N- rate was sig-

nificant. Where K2S04 or KC1 was the K- source, the plant fresh

weight increased as the N- rate was increased from 52 to 100

pounds per acre. Further increase in the rate of N to 148 pounds







Table 23. Effect of potassium source and rate of potassium and
size of fresh fruit from March 25 and April 11, 1966 pickings.


nitrogen on average


Rate Fruit size (g per fruit)
lb/acre March 25 April 11
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 11.2 10.8 11.0 11.0 10.4 8.5 8.8 9.2
90 11.0 9.9 11.3 10.7 9.5 8.5 9.2 9.1
145 10.7 11.0 11.0 10.9 9.1 8.3 9.5 8.9
Mean 11.0 10.6 11.1 10.9 9.7 8.4 9.2 9.1

100 35 11.5 12.0 10.9 11.5 9.6 9.4 9.8 9.6
90 12.8 11.7 10.4 11.6 9.7 9.8 8.5 9.3
145 9.9 10.5 10.9 10.4 10.0 9.8 6.6 8.8
Mean 11.4 11.4 10.7 11.2 9.8 9.7 8.3 9.2

148 35 12.7 12.0 10.6 11.8 9.5 8.1 9.6 9.1
90 11.3 11.1 10.1 10.8 8.6 8.5 9.3 8.8
145 10.5 11.1 10.3 10.6 9.0 8.3 10.2 9.2
Mean 11.5 11.4 10.3 11.1 9.0 8.3 9.7 9.0

35 11.8 11.6 10.8 11.4 9.8 8.7 9.4 9.3
90 11.7 10.9 10.6 11.1 9.3 8.9 9.0 9.1
145 10.4 10.8 10.7 10.6 9.4 8.8 8.8 9.0
Mean 11.3 11.1 10.7 11.0 8.5 8.8 9.1 9.1
100 0 11.0 10.5
Significant treatment effects:


March 25 -
April 11 -


K rate effect is linear*.
K2SO4 vs. KC1 x N quadratic*.
K2SO4+KC1 vs. KNO3 x N quadratic**.


*Significant at 5% level of P.
**Significant at 1% level of P.








Table 24.
fresh and


Effect of potassium source and rate of potassium and nitrogen on total
dry weight of seven plant tops on May 31, 1966.


Rate Total weight of seven plant tops (g____________________
lb/acre Fresh weight Dry weight
N K K2SO4 KN03 KC1 Mean K2SO4 KNO3 KCl Mean

52 35 541.3 746.7 592.3 626.8 168.0 210.0 178.0 185.3
90 745.0 632.7 631.0 669.6 221.3 183.7 174.0 193.0
145 477.3 638.3 546.0 553.9 158.0 183.7 174.7 172.1
Mean 587.9 672.6 589.8 616.8 182.4 192.5 175.6 183.5

100 35 638.3 559.3 601.3 599.7 179.3 177.3 193.7 183.4
90 .772.3 604.7 652.0 676.3 259.7 194.7 185.7 213.4
145 770.0 491.3 791.3 684.2 231.7 155.0 257.3 214.7
Mean 727.0 551.8 681.5 653.4 223.6 175.7 212.2 203.8

148 35 650.7 523.0 529.3 567.7 165.3 142.3 166.3 158.0
90 678.3 553.3 649.0 626.9 169.7 171.7 189.0 176.8
145 657.3 635.3 763.7 685.4 189.3 161.7 233.0 194.7
Mean 662.1 570.5 647.3 626.6 174.8 158.6 196.1 176.5

35 610.2 609.7 574.3 598.0 170.9 176.5 179.3 175.6
90 731.9 596.9 644.0 657.6 216.9 183.4 182.9 194.4
145 634.9 588.3 700.3 641.2 193.0 166.8 221.7 193.8
Mean 659.0 598.3 639.5 632.3 193.6 175.6 194.6 187.9
100 0 396.0 118.0


Significant treatment effects:
Fresh weight K2SO4+KCI vs. KNO3 x N quadra
N linear x K linear*.
Dry weight N rate effect is quadratic*.
K2SO4 vs. KC1 x K quadratic*.


tic*.


*Significant at 5% level of P.










per acre, resulted in a reduction in the plant fresh weight.

Whereas, with the KNO3 source of K, plant fresh weights were

reduced linearly as the N- rate was increased. Fresh weights

were also significantly influenced by an interaction between the

rate of N and rate of K. At the 52 pounds per acre rate of N,

an increase in the rate of K above 90 pounds per acre resulted

in a reduction in the plant size. However, at 100 and 148

pounds per acre rates of N, plant fresh weights increased with

increased rates of K.

The main effect of N- rate on total dry weight of plants

was quadratic. The weight of plant tops increased from 183.5 to

203.8 grams with increased rates of N from 52 to 100 pounds per

acre. Further increases in the N- rate to 148 pounds per acre

resulted in a reduction in the dry weight to 176.5 grams. A

significant interaction between the source of K and rate of K

indicated that, at 35 and 145 pounds per acre rates of K, KC1 as

the K-source produced plants with greater dry matter than plants

grown with the K2S04 source of K.

Plots not receiving K produced plants with much lower

fresh as well as dry weights as compared to those receiving K-

fertilization. Figures 3 and 4 show the differences in the

vegetative growth of plants, at the end of the fruiting season

from plots not receiving K (Figure 3) and plants fertilized

with 145 pounds per acre K as KC1 (Figure 4).

Fresh and stored fruit quality

Firmness -- Results of compression and shear resistance

measurements from three samples of fresh fruits are shown in




































Figure 3.
ceiving K,


Condition of plants from plots not re-
at the end of the 1966 fruiting season.


Figure 4. Condition of plants from plots receiving
145 pounds per acre K as KC1, at the end of the 1966
fruiting season.









Tables 25, 26 and 27. The compression resistance of fruits did

not show significant variation due to treatments in the April 11

and April 18 samples (Tables 25, 26). However, at both samplings

there was a trend for reduction in the compression resistance

with increased rates of K. The main effect of K- source on

compression resistance was significant at the May 2 picking

(Table 27). Fruits produced in plots receiving KNO3 as the K-

source were firmer than where K2SO4 or KC1 had been applied.

However, an interaction between K- source and rate of N was also

significant. Where the K- source was KN03, compression resistance

of the fruit increased linearly from 39.9 to 47.7 pounds per 100

g fruit, with increased rates of N from 52 to 148 pounds per

acre. But with K2S04 or KC1 as the source of K the compression

resistance decreased from 41.1 to 40.6 pounds and from 42.1 to

38.7 pounds, respectively.

At the April 18 sampling, the shear resistance of fresh

fruits was significantly greater where K2SO4 was the source of

K as compared to KC1 (Table 25). The shear resistance appeared

to decrease with increased rates of K at all the three samplings.

This significant reduction was linear in the April 18 samples.

The shear resistance was reduced from 88.1 to 81.3 pounds as the

K- rate was increased from 35 to 145 pounds per acre.

At the April 18 sampling, the shear resistance of fruit

was lowest from plots fertilized with 100 pounds per acre N,

and higher with 52 and 148 pounds per acre rates of N. This

main effect of the N- rate was modified by a significant inter-

action with source of K. The shear resistance of fruits from the








Effect of potassium source and rate of potassium and nitrogen on compression


and shear resistance of fresh strawberries from April 11, 1966 picking.

Rate Compression and shear'resistance (lb/100 g fruit)
lb/acre Compression Shear
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean


52 35 53.3 47.5 48.3 49.7 80.0 75.8 80.0 78.6
90 49.2 57.5 53.3 53.3 83.3 77.5 80.8 80.5
145 55.0 54.2 49.2 52.8 82.5 81.7 76.7 80.3
Mean 52.5 53.1 50.3 51.9 81.9 78.3 79.2 79.8

100 35 52.5 57.5 50.0 53.3 84.2 90.0 75.8 83.3
90 53.3 49.2 61.7 54.7 86.7 71.7 85.0 81.1
145 55.8 46.7 54.2 52.2 88.3 68.3 82.5 79.7
Mean 53.9 51.1 55.3 53.4 86.4 76.7 81.1 81.4

148 35 54.2 52.5 73.3 60.0 80.8 84.2 75.8 80.3
90 48.3 50.8 47.5 48.9 80.0 81.7 71.7 77.8
145 52.5 50.0 50.0 50.8 90.8 75.0 70.8 78.9
Mean 51.7 51.1 56.9 53.2 83.9 80.3 72.8 79.0

35 53.3 52.5 57.2 54.7 81.7 83.3 77.2 80.7
90 50.3 52.5 54.2 52.3 83.3 77.0 79.2 79.8
145 54.4 50.3 51.1 51.9 87.2 75.0 76.7 79.6
Mean 52.7 51.8 54.2 52.9 84.1 78.4 77.7 80.0
100 0 55.8 103.2


Significant treatment
Shear Mean of K2SO4


effects:
is greater


than mean of KC1*.


*Significant at 5% level of P.


Table 25.








Table 26. Effect of potassium source and rate of potassium and nitrogen on compression
and shear resistance of fresh strawberries from April 18, 1966 picking.

Rate Compression and shear resistance (lb/100 g fruit)
Ib/acre Compression Shear
N K K2SO4 KNO3 KCI Mean K2SO4 KNO3 KC1 Mean

52 35 64.2 54.2 55.0 57.8 93.3 81.7 87.5 87.5
90 48.3 57.5 54.2 53.3 76.7 86.7 84.2 82.5
145 53.3 57.5 50.8 53.9 80.0 87.5 82.5 83.3
Mean 55.3 56.4 53.3 55.0 80.3 85.3 84.7 83.4

100 35 50.8 50.0 60.0 53.6 87.5 77.5 85.8 83.6
90 55.0 56.7 58.3 56.7 75.0 78.3 91.7 81.7
145 51.7 55.0 51.7 52.8 75.8 71.7 86.7 78.1
Mean 52.5 53.9 56.7 54.4 79.4 75.8 88.1 81.1

148 35 50.0 65.8 60.0 58.6 87.5 100.0 92.5 93.3
90 58.3 57.5 54.2 56.7 76.7 90.8 82.5 83.3
145 55.0 62.5 55.8 57.8 81.7 91.7 74.2 82.5
Mean 54.4 61.9 56.8 57.7 81.9 94.2 83.1 86.4

35 55.0 56.7 58.3 56.7 89.4 86.4 88.6 88.1
90 53.9 57.2 55.6 55.6 76.1 85.3 86.1 82.5
145 53.3 58.3 52.8 54.8 79.2 83.6 81.1 81.3
Mean 54.1 57.4 55.6 55.7 81.6 85.1 85.3 83.9
100 0 60.8 99.2
Significant treatment effects:


Shear N rate effect
K rate effect
K2SO4+KC1 vs.


is quadratic*.
is linear**.
KNO3 x N quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.








Table 27. Effect of potassium source and rate of potassium and nitrogen on compression
and shear resistance of fresh strawberries from May 2, 1966 picking.

Rate Compression and shear resistance (lb/100 g fruit)
Ib/acre Compression Shear
N K K2SO4 KN03 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 43.2 39.2 41.7 41.4 57.9 49.2 50.4 52.5
90 38.3 41.3 43.8 41.1 50.0 50.8 56.6 52.5
145 41.7 39.2 40.8 40.6 53.3 .51.3 47.5 50.7
Mean 41.1 39.9 42.1 41.0 53.7 50.4 51.5 51.9

100 35 40.8 40.8 44.6 42.1 53.3 47.5 51.3 50.7
90 38.3 39.2 44.2 40.6 52.1 51.3 51.3 51.6
145 38.7 48.3 38.3 41.8 51.7 60.0 48.3 53.3
Mean 39.3 42.8 42.4 41.5 52.4 52.9 50.3 51.9

148 35 39.2 49.6 45.8 44.9 55.4 58.3 54.2 56.0
90 41.7 44.6 35.4 40.6 49.2 54.2 44.2 49.2
145 40.8 47.9 35.0 41.2 50.4 60.0 51.3 53.9
Mean 40.6 47.4 38.7 42.2 51.7 57.5 49.9 53.0

35 41.2 43.2 44.0 42.8 55.5 51.7 52.0 53.2
90 39.4 41.7 41.1 40.7 50.4 52.1 .50.7 51.1
145 40.4 45.1 38.0 41.2 51.8 57.1 49.0 52.6
Mean 40.3 43.2 41.0 41.6 52.6 53.6 50.6 52.3
100 0 42.1 49.6
Significant treatment effects:


Compression

Shear


- Mean of K2S04+KCI is less than mean
K2SO4+KC1 vs. KN03 x N linear-*.
- %SO4+KC1 vs. KNO3 x N linear*.
K2S04+KC1 vs. KNO x K linear*.


of KNO*.


*Significant at 5% level of P.
**Significant at 1% level of P.










May 2 picking was considerably less than that from the April 11

and April 18 samples (Table 27). Shear resistance at the May 2

sampling was significantly affected by interactions between K-

source and rate of N and K. Where the K- source was KNO3 the

fruit shear resistance increased linearly with increased rates

of N or K. Similar increased rates of either N or K resulted

in a reduction in shear resistance where the source of K was

K2SO4 or KC1.

Fruits from plots not receiving K fertilizer, were higher

in their shear resistance than those from the plots fertilized

with K, in the April 11 and April 18 samples. However, in the

May 2 samples the shear resistance of fruits from plots not

receiving K was less than those which received K fertilizers.

The shear resistance of fruits from plots not receiving K fell

consistently as the fruiting season progressed. This was less

so in the fruits from plots fertilized with K.

Tables 28, 29, 30 and 31 show the data from compression

and shear resistance measurements on the stored fruits from three

pickings. In this experiment the duration of storage varied.

Fruits from the April 11 picking were stored for four days,

those from the April 18 picking were stored for four and eight

days; and those from the May 2 picking were stored for eight

days. All fruit storage were at 38 F temperature.

The compression resistance in the four-days stored

fruits from the April 11 picking was not significantly affected

by treatments. After four days of storage the compression re-

sistance of fruits from the April 18 picking was significantly








Table 28.
and shear
storage.


Effect of potassium source and rate of potassium and nitrogen on compression
resistance of strawberries from April 11, 1966 picking after four days in


Rate Compression and shear resistance (lb/100 g fruit)
Ib/acre Compression Shear
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 60.0 58.3 55.8 58.0 92.5 85.8 85.8 88.0
90 50.8 63.3 59.2 57.8 77.5 85.0 90.0 84.1
145 60.0 53.0 55.0 56.7 81.7 84.1 85.0 83.6
Mean 56.9 58.9 56.7 57.5 83.9 85.0 86.9 85.2

100 35 52.5 60.0 55.8 56.1 81.7 83.3 85.0 83.3
90 65.0 55.0 52.5 57.5 85.8 79.2 80.0 81.7
145 51.5 57.5 57.5 56.3 80.0 75.8 80.8 78.9
Mean 56.4 57.5 55.3 56.3 82.5 79.4 81.9 81.3

148 35 55.0 62.5 55.8 57.8 82.5 91.7 88.3 87.5
90 58.3 65.8 55.0 59.7 82.5 93.3 70.8 82.2
145 56.7 55.0 58.3 .56.7 95.8 75.0 82.5 84.4
Mean 56.7 61.1 56.4 58.1 86.9 86.7 80.5 84.7

35 55.8 60.3 55.8 57.3 85.5 86.9 86.4 86.3
90 58.0 61.4 55.6 58.3 81.9 85.8 80.3 82.7
145 56.1 55.8 56.9 56.3 85.8 78.3 82.7 82.3
Mean 56.6 59.2 56.1 57.3 84.4 83.7 83.1 83.8
100 0 57.5 101.7
Treatment effects not significant.








Table 29.
and shear
storage.


Effect of potassium source and rate of potassium and nitrogen on compression
resistance of strawberries from April 18, 1966 picking after four days in


Rate C6mpression and shear resistance (lb/100 g fruit)
Ib/acre Compression Shear
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 64.2 57;5 56.7 59.5 87.5 84.2 83.3 85.0
90 67.5 59.2 55.8 60.8 85.8 84.2 92.5 87.5
145 55.8 53.3 56.7 55.3 77.5 79.1 86.7 81.1
Mean 62.5 56.7 56.4 58.5 83.6 82.5 87.5 84.5

100 35 55.8 54.2 49.2 53.1 87.5 79.1 76.7 81.1
90 60.0 52.5 51.7 54.7 83.3 83.3 82.5 83.0
145 57.5 50.8 51.7 53.3 88.3 80.0 77.5 81.9
Mean 57.8 52.5 50.9 53.7 86.3 80.1 78.9 81.8

148 35 55.0 58.3 56.7 56.7 86.7 93.3 94.2 91.4
90 52.5 60.0 55.8 56.1 88.3 90.8 85.0 88.0
145 58.3 58.3 60.0 58.9 89.2 88.3 87.5 88.3
Mean 55.3 58.9 57.5 57.7 88.1 90.8 88.9 89.3

35 58.3 56.7 54.2 56.4 87.2 85.5 84.7 85.8
90 60.0 57.2 54.4 57.2 85.8 86.1 86.7 86.2
145 57.2 54.1 56.1 55.8 85.0 82.5 83.9 83.8
Mean 58.5 56.0 54.9 56.5 86.0 84.7 85.1 85.3
100 0 55.8 99.2


Significant
Compression

Shear


treatment effects:
- Mean of K2SO4 is
N rate effect is
- N rate effect is


greater than mean
quadratic**.
quadratic*.


of KC1*.


*Significant at 5% level of P.
**Significant at 1% level of P.








Table 30.
and shear
storage.


Effect of potassium source and rate of potassium and nitrogen on compression
resistance of strawberries from April 18, 1966 picking after eight days in


Rate Compression and shear resistance (lb/100 g fruit)
lb/acre Compression Shear
N K K2S04 KNO3 KC1 Mean K2SO4 KN03 KC1 Mean

52 35 60.8 55.8 63.3 59.9 90.0 76.7 86.7 84.5
90 60.0 62.5 53.3 58.6 84.2 82.5 78.3 81.7
145 56.7 55.8 57.5 56.7 80.8 80.0 85.0 81.9
Mean 59.2 58.0 58.0 58.4 85.0 79.7 83.3 82.7

100 35 63.3 64.2 54.1 60.5 86.7 93.3 81.7 87.2
90 57.5 60.0 55.0 57.5 81.7 89.2 81.7 84.2
145 60.0 57.5 59.1 58.9 84.2 81.7 88.3 84.7
Mean 60.0 60.0 56.1 59.0 84.2 88.1 83.9 85.4

148 35 67.5 65.8 62.5 65.3 101.7 90.0 90.8 94.2
90 60.0 59.2 53.3 57.5 80.0 76.7 80.0 78.9
145 61.6 59.2 60.0 60.3 86.7 71.7 84.1 80.8
Mean 63.0 61.4 58.6 61.0 89.5 79.5 85.0 84.7

35 63.9 61.9 60.0 61.9 92.8 86.7 86.4 88.6
90 59.2 60.6 53.9 57.9 82.0 82.8 80.0 81.6
145 59.4 57.5 58.9 58.6 83.9 77.8 85.8 82.5
Mean 60.8 60.0 57.6 59.5 86.2 82.4 84.1 84.2
100 0 59.2 94.2
Significant treatment effects:
Shear K rate effect is linear*.
K2SO4+KC1 vs. KNO3 x N quadratic-.


*Significant at 5% level of P.








Table 31.
and shear
storage.


Effect of potassium source and rate of potassium and nitrogen on compression
resistance of strawberries from May 2, 1966 picking after eight days in


Rate Compression and shear resistance (lb/100 g fruit)
lb/acre Compression Shear
N K K2SO4 KNO3 KC1 Mean K2S04 KNO3 KC1 Mean

52 35 50.0 43.8 50.0 47.9 62.5 57.5 55.4 58.5
90 54.2 49.2 48.3 50.6 62.1 57.1 55.0 58.1
145 44.6 43.8 50.9 46.4 57.9 52.1 57.1 55.7
Mean 49.6 45.6 49.7 48.3 60.8 55.6 55.8 57.4

100 35 51.7 47.1 50.9 49.9 64.2 59.6 59.6 61.1
90 47.9 46.3 47.1 47.1 59.2 54.2 52.5 55.3
145 52.1 53.4 45.0 50.2 58.4 63.8 55.8 59.3
Mean 50.6 48.9 47.7 49.1 60.6 59.2 56.0 58.6

148 35 55.8 55.4 52.1 54.4 60.0 58.4 63.8 60.7
90 57.9 49.2 45.4 50.8 65.8 55.0 52.5 57.8
145 57.9 51.3 47.9 52.4 67.1 55.8 56.3 59.7
Mean 57.2 52.0 48.5 52.6 64.3 56.4 57.5 59.4

35 52.5 48.8 51.0 50.8 62.2 58.5 59.6 60.1
90 53.3 48.2 46.9 49.5 62.4 55.4 53.3 57.0
145 51.5 49.5 47.9 49.6 61.1 .57.2 56.4 58.2
Mean 52.4 48.8 48.6 50.0 61.9 57.0 56.4 58.4
100 0 42.5 49.6


Significant
Compression
Shear


treatment effects:
- N rate effect is
- Mean of K2SO4 is


linear.
greater than mean


of KCl*.


*Significant at 5% level of P.









influenced by K- source, and N- rate. The compression resistance

was higher when the source of K applied was K2SO4 than with KC1

and intermediate with KNO3 (Table 29). The N- rate effect on

compression resistance was quadratic, and the resistances were

58.5, 53.7, and 57.5 pounds at 52, 100 and 148 pounds per acre

N- rates, respectively. After eight days of storage however,

the compression resistance of samples from the April 18 picking

were not significantly influenced by treatments. After eight

days of storage the fruit from May 2 picking, the effect of N-

rate was significant. The compression resistance of the fruit

was increased linearly from 48.3 to 52.6 pounds as the rate of

N was increased from 52 to 148 pounds per acre (Table 31).

The shear resistance of fruits from the April 11 picking

was not influenced by treatments (Table 28). Fruit from the

April 18 picking after four days of storage,however, were sig-

nificantly influenced by N- rate (Table 29). Shear resistance

was reduced from 84.5 to 81.8 pounds as the rate of N was in-

creased from 52 to 100 pounds per acre. A further increase in

the rate of N to 148 pounds per acre resulted in an increase in

the shear resistance to 89.3 pounds. After eight days in storage

(Table 30), the shear resistance of stored fruit was decreased

linearly from 88.6 to 82.5 pounds as the rate of K was increased

from 35 to 145 pounds per acre. An interaction between the

source of K and N- rate was also significant. Where the K-

source was K2SO4 or KC1, the shear resistance increased linearly

with increased rates of N. However, with KNO3 as the source of









K, the shear resistance increased with increased rates of N

from 52 to 100 pounds per acre. A further increase in N- rate

to 148 pounds per acre resulted in a reduction in the shear

resistance of the fruits. The shear resistance of stored fruits

from all the samplings was slightly higher where the K- source

was K2S04. This effect was significant in the stored samples

from the May 2 picking. Shear-resistances were 61.9 pounds

where the K- source was K2SO4 and were 57.0 and 56.4 pounds

with KNO3 and KC1 sources respectively.

The shear resistance of stored fruits from plots not

fertilized with K were higher in the April 18 picking, but lower

in the May 2 picking than fruits from plots fertilized with K.

Soluble solids -- Soluble solid contents of fresh fruits

from three pickings were not significantly affected by treat-

ments (Table 32). Fruits from plots not fertilized with K showed

a consistent decrease in the soluble solids content as the season

progressed.

After four or eight days of storage, various treatments

significantly influenced the fruit soluble solids content

(Table 33). Soluble solids content increased linearly with

increased rates of applied K at all samplings. The increase,

which was 0.13 to 0.15 per cent was significant only at the

March 25 sampling. Significant interactions between K- source

and rates of N and K occurred at all samplings. These were in-

consistent and difficult to interpret.








Table 32. Effect of potassium source and rate of potassium and nitrogen on soluble solids
content of fresh strawberries from March 25, April 11, and April 18, 1966 pickings.

Rate Soluble solids (per cent)
lb/acre March 25 April 11 April 18
N K K2S04 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean K2S04 KNO3 KC1 Mean

52 35 7.10 8.10 7.60 7.60 6.80 6.10 6.80 6.57 7.66 7.10 6.57 7.11
90 7.10 7.10 7.70 7.30 7.10 6.20 6.40 6.57 6.96 7.47 6.80 7.08
145 7.20 7.90 7.30 7.47 7.20 6.50 6.30 6.67 7.13 6.60 6.90 6.88
Mean 7.13 7.70 7.53 7.45 7.03 6.27 6.50 6.50 7.25 7.06 6.76 7.02

100 35 7.70 7.50 7.00 7.40 6.20 6.50 6.90 6.53 6.77 6.70 6.77 6.75
90 7.30 7.50 7.70 7.50 6.70 6.90 6.00 6.53 6.90 7.50 6.90 7.10
145 7.70 8.20 7.50 7.80 7.00 6.80 6.80 6.87 7.43 7.60 6.20 7.08
Mean 7.56 7.73 7.40 7.56 6.63 6.73 6.57 6.64 7.03 7.27 6.62 6.98

148 35 7.00 7.70 7.70 7.47 6.60 6.60 6.40 6.53 6.87 6.67 6.93 6.82
90 7.40 7.20 7.50 7.37 6.70 6.70 6.90 6.77 7.00 7.23 6.77 7.00
145 6.80 7.40 7.40 7.20 6.60 6.30 6.20 6.37 7.03 7.47 7.70 7.40
Mean 7.06 7.43 7.53 7.34 6.63 6.53 6.50 6.55 6.97 7.12 7.13 7.07

35 7.30 7.77 7.43 7.50 6.53 6.40 6.70 6.54 7.10 6.82 6.76 6.89
90 7.26 7.27 7.63 7.39 6.83 6.60 6.43 6.62 6.95 7.40 6.82 7.06
145 7.23 7.83 7.40 7.49 6.93 6.53 6.43 6.63 7.20 7.22 6.93 7.12
Mean 7.26 7.62 7.49 7.46 6.76 6.51 6.52 6.60 7.08 7.15 6.84 7.02
100 0 7.30 7.00 6.50
Treatment effects not significant.








Table 33. Effect of potassium source and rate of potassium and nitrogen on soluble solids
content of strawberries from March 25, April 11, and April 18, 1966 pickings after storage
for eight, four and eight days respectively.

Rate Soluble solids (per cent)
lb/acre March 25 April 11 April 18
N K K2SO4 KN03 KC1 Mean K2SO4 KNO3 KC1 Mean K2S04 KNO3 KC1 Mean

52 35 6.30 6.70 6.10 6.37 6.90 6.20 6.40 6.50 6.90 7.40 7.20 7.17
90 6.80 6.80 6.40 6.67 6.80 6.20 6.50 6.50 7.00 6.70 7.20 6.97
145 7.30 7.70 7.10 7.37 6.60 6.50 7.00 6.70 7.20 7.20 6.90 7.10
Mean 6.80 7.07 6.53 6.80 6.77 6.30 6.63 6.57 7.03 7.10 7.10 7.08

100 35 6.70 6.90 6.80 6.80 6.10 6.90 6.30 6.43 6.60 6.40 7.50 6.83
90 7.50 6.40 7.30 7.07 6.60 7.20 6.60 6.80 6.80 7.40 6.80 7.00
145 7.00 7.00 6.70 6.90 6.90 7.10 6.90 6.96 7.30 7.30 7.10 7.23
Mean 7.07 6.77 6.93 6.92 6.53 7.07 6.60 6.73 6.90 7.03 7.13 7.02

148 35 6.70 7.10 6.40 6.73 7.00 6.40 6.30 6.57 6.50 6.90 7.30 6.90
90 6.50 7.00 5.90 6.47 6.30 6.50 6.60 6.47 7.50 7.30 7.00 7.27
145 6.10 6.90 6.90 6.63 6.70 6.80 6.70 6.73 6.90 7.50 6.90 7.10
Mean 6.43 7.00 6.40 6.61 6.67 6.57 6.53 6.59 6.97 7.23 7.07 7.09

35 6.57 6.90 6.43 6.63 6.67 6.50 6.33 6.50 6.67 6.90 7.33 6.97
90 6.93 6.73 6.53 6.73 6.57 6.63 6.57 6.59 7.10 7.13 7.00 7.08
145 6.80 7.20 6.90 6.97 6.73 6.80 6.87 6.80 7.13 7.33 6.97 7.14
Mean 6.77 6.94 6.62 6.78 6.66 6.64 6.59 6.63 6.97 7.12 7.10 7.06
100 0 6.00 6.30 7.20
Significant treatment effects:


March 25 -


K rate effect is linear*.
N linear x K linear**.
K2S04+KC1 vs. KNO3 x N quadratic**.


April 11 K2S04+ KC1 vs. KNO3 x N quadratic*.
K2SO4 vs. KC1 x K linear*.


*Significant at 5% level of P.
**Significant at 1% level of P.










Dry matter content -- Dry matter content of the fresh

fruits from March 25 and April 11 pickings were not significantly

'ffcc ted by treatmner.:s /0n(7 < ?I) T'it --v

frdsh samples from the April 18 picking was significantly in-

creased with increased rate of K. The linear increase was from

8.39 to 8.93 per cent as the K- rate increased from 35 to 145

pounds per acre. An interaction between the source of K and N-

rate was also significant in April 18 samples. Where the K-

source was K2S04, increased N- rate from 52 to 100 pounds per

acre, increased the dry matter content of fresh fruits from 8.43

to 8.90 per cent. Further increase in the rate of N to 148

pounds per acre reduced the dry matter content of fruit to 8.51

per cent. Where the K- source was KC1, increasing the N- supply

from 52 to 100 pounds per acre reduced the fruit dry matter

content. Further increase in the N- rate to 148 pounds per acre

increased the fruit dry matter levels.

After eight days of storage of the March 25 samples, the

fruit dry matter content was significantly influenced by an

interaction between K- source and N- rate. Where KC1 was the

source of K, fruit dry matter content increased from 8.92 to 9.19

per cent as N- rates increased from 52 to 148 pounds per acre.

With K2SO4 as the source of K the dry matter content of fruits

decreased from 9.39 to 8.71 per cent as the N- rate increased

from 52 to 148 pounds per acre. After eight days of storage

of the April 18 sample, the dry matter content of fruits from

plots fertilized with KNO3 was significantly higher as compared

to fruits from K2SO4 or KC1 fertilized plots. Source of K








Table 34. Effect of potassium source and rate of potassium and nitrogen on
of fresh strawberries from March 25, April 11, and April 18, 1966 pickings.


dry matter content


Rate Dry matter (per cent)
Ib/acre March 25 April 11 April 18
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KCI Mean

52 35 8.51 9.25 8.42 8.73 9.68 9.39 9.33 9.47 8.17 8.42 8.74 8.44
90 8.58 8.53 8.27 8.46 10.19 9.27 9.59 9.68 8.55 9.00 8.67 8.74
145 8.25 8.73 8.51 8.49 9.17 9.34 9.54 9.35 8.56 9.25 8.75. 8.85
Mean 8.45 .8.84 8.40 8.56 9.68 9.33 9.49 9.50 8.43 8.89 8.72 8.68

100 35 8.66 8.97 8.35 8.66 9.21 9.58 8.77 9.19 9.07 8.73 8.33 8.71
90 8.47 8.70 8.43 8.53 8.99 9.52 9.94 9.48 8.41 9.60 8.10 8.70
145 8.81 8.42 8.58 8.60 9.73 9.99 9.26 9.66 9.23 9.12 8.31 8.89
Mean 8.65 8.69 8.45 8.59 9.31 9.69 9.32 9.44 8.90 9.15 8.25 8.77

148 35 8.64 8.12 8.33 8.36 8.72 9.42 8.54 8.89 8.15 7.89 8.03 8.02
90 8.67 8.65 8.07 8.46 9.46 9.32 10.08 9.62 8.65 8.08 8.31 8.35
145 8.46 8.81 8.07 8.45 9.83 9.49 9.31 9.54 8.72 8.73 9.70 9.05
Mean 8.59 8.53 8.16 8.42 9.34 9.41 9.31 9.35 8.51 8.23 8.68 8.47

35 8.60 8.78 8.37 8.58 9.20 9.46 8.88 9.18 8.46 8.35 8.37 8.39
90 8.57 8.63 8.26 8.49 9.54 9.37 9.87 9.59 8.54 8.89 8.82 8.75
145 8.51 8.65 8.39 8.52 9.58 9.61 9.37 9.52 8.84 9.03 8.92 8.93
Mean 8.56 8.69 8.34 8.53 9.44 9.48 9.37 9.43 8.61 8.76 8.70 8.69
100 0 8.35 9.24 7.74
Significant treatment effects:
April 18 K rate effect is linear**.
K2SO4 vs. KC1 x.N quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.







Table 35. Effect of potassium source and rate of potassium and nitrogen on dry matter content
of strawberries from March 25, April 11, and April 18, 1966 pickings after storage for eight,
four and eight days respectively.

Rate Dry matter (per cent
lb/acre March 25 April 11 April 18
N K K2SO4 KNO3 KCl Mean K2SO4 KNO3 KC1 Mean K2S04 KNO3 KC1 Mean

52 35 9.14 9.23 9.34 9.33 9.92 9.27 8.84 9.34 9.29 9.37 8.50 9.05
90 9.20 9.34 8.41 8.09 9.15 9.30 9.86 9.44 9.27 9.81 9.19 9.42
145 9.57 9.24 9.00 9.27 9.37 9.00 8.88 9.08 9.33 9.24 8.89 9.15
Mean 9.39 9.27 8.92 9.19 9.48 9.19 9.19 9.29 9.29 9.47 8.86 9.21

100 35 9.23 9.45 9.34 9.34 8.85 10.51 9.10 9.49 8.61 9.17 9.71 9.16
90 9.45 8.70 9.20 9.12 9.45 9.64 9.23 9.44 9.85 10.09 9.05 9.66
145 8.97 9.37 8.72 9.02 9.56 9.58 9.06 9.40 8.80 9.85 8.67 9.11
Mean 9.22 9.17 9.09 9.16 9.29 9.91 9.13 9.44 9.09 9.70 9.14 9.31

148 35 8.45 9.00 9.81 9.09 9.15 8.89 8.45 8.83 9.24 9.11 9.06 9.14
90 8.85 8.82 8.31 8.66 9.05 9.42 9.08 9.18 9.44 9.57 9.86 9.62
145 8.83 9.07 9.44 9.11 9.69 9.53 9.36 9.53 9.10 10.59 9.25 9.65
Mean 8.71 8.96 9.19 8.95 9.29 9.28 8.96 9.18 9.26 9.76 9.39 9.47

35 9.03 9.23 9.49 9.25 9.31 9.56 8.79 9.22 9.05 9.22 9.09 9.12
90 9.17 8.93 8.64 8.92 9.22 9.45 9.39 9.35 9.52 9.82 9.37 9.57
145 9.12 9.23 9.05 9.13 9.54 9.37 9.10 9.34 9.08 9.89 8.94 9.42
Mean 9.11 9.14 9.06 9.10 9.36 9.46 9.09 9.30 9.22 9.64 9.13 9.33
100 0 8.37 9.34 9.99
Significant treatment effects:


March 25 K2SO4 vs. KC1 x N linear*.
K2SO4+KC1 vs. KNO3 x N quadratic*.
N linear x K linearx-.


April 18 Mean of K2SO4+KC1 is less than
mean of KNO3*-.
K2SO4+KCI vs. KNO3 x K linear*.
K rate effect is quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.









interacted significantly with the rate of K in stored fruits from

the April 18 picking. With KNO3 as the source of K, increased

rates of K from 35 to 145 pounds per acre resulted in a linear

increase in the fruit dry matter content. Where the K- source

was K2SO4 or KC1, the K- rate affected the fruit dry matter

content quadratically (Table 35).

After four days of storage, fruits from the April 11

picking were significantly influenced by an interaction between

K- source and rate of N. When the K- source was KNO3 the fruit

dry matter content increased from 9.19 to 9.91 per cent as the

N- rate was increased from 52 to 100 pounds per acre. With a

further increase in the N supply to 148 pounds per acre, fruit

dry matter content was reduced to 9.28 per cent. With K2S04

or KC1 as the source of K, increased rates of N resulted in a

linear reduction in the fruit dry matter content. An inter-

action between the rate of N and rate of K was also significant

at the April 11 picking. At 35 and 90 pounds per acre rates of

K the dry matter content of four days stored fruit from the April

11 picking reduced with increased rates of N. However, at the

145 pounds rate of K, the dry matter content of fruit increased

linearly from 9.08 to 9.53 per cent with an increase in the N-

rate from 52 to 148 pounds per acre.

Total titratable acidity -- Total titratable acidity of

fresh fruits from the March 25 picking was significantly greater

when K2SO4 was the source of K as compared with KC1 (Table 36).

An interaction between the rate of N and rate of K was also

significant. At the 35 pounds per acre rate of K, increased








Table 36. Effect of potassium source and rate of potassium and nitrogen on total titratable
acidity of fresh strawberries from March 25, April 11 and April 18, 1966 pickings.

Rate Total titratable acidity (meq. NaOIl)
lb/acre March 25 April 11 April 18
N K K2SO4 KNO3 Kcl Mean K2S04 KNO3 KCl Mean K2S04 KN03 KCl Mean


52 35 19.6 17.5 17.6 18.2 18.3 18.3 18.2 18.3 19.0 18.4 18.4 18.6
90 17.5 17.6 17.2 17.4 19.2 19.7 19.2 19.4 18.1 19.2 17.6 18.3
145 18.5 19.3 16.2 18.0 19.5 19.9 18.5 19.3 20.0 19.3 20.1 19.8
Mean 18.5 18.1 17.0 17.8 19.0 19.3 18.6 19.0 19.0 19.0 18.7 18.9

100 35 17.8 19.1 17.3 18.1 17.5 18.7 19.1 18.4 19.0 18.3 18.0 18.4
90 18.9 18.1 18.5 18.5 19.9 21.3 21.7 20.9 20.9 20.3 19.5 20.2
145 18.6 17.8 17.5 17.9 19.4 20.2 18.8 19.5 19.3 19.7 19.8 19.6
Mean 18.4 18.3 17.8 18.2 18.9 21.2 19.9 19.6 19.7 19.4 19.1 19.4

148 35 17.2 16.6 17.1 16.9 17.9 17.9 19.6 18.5 17.7 18.6 18.1 18.1
90 18.1 18.2 18.7 18.3 19.2 19.2 19.8 19.4 18.7 19.7 17.8 18.7
145 19.2 18.6 18.3 18.7 19.5 18.9 19.2 19.2 19.6 19.9 18.9 19.5
Mean 18.2 17.8 18.0 18.0 18.9 18.7 19.5 19.0 18.6 19.4 18.3 18.8

35 18.2 17.7 17.3 17.7 17.9 18.3 19.0 18.7 18.6 18.4 18.2 18.4
90 18.2 17.9 18.1 18.1 19.4 20.1 20.2 19.9 19.2 19.7 18.3 19.1
145 18.8 18.6 17.3 18.2 19.5 19.7 18.8 19.3 19.6 19.6 19.6 19.6
Mean 18.4 18.1 17.6 18.0 18.9 19.4 19.3 19.3 19.1 19.2 18.7 19.0
100 0 18.0 18.8 17.9
Significant treatment effects:


March 25 Mean of K2SO4 is greater than
mean of KC1.
N linear x K linear-".


April 11 N
K
April 18 K


rate effect is
rate effect is
rate effect is


quadratic*.
linear'*.
linear**.


N quadratic x K quadratic*.


*Significant at 5% level of P.
**Significant at 1% level of P.










rate of N reduced the total titratable acidity of the fresh fruit.

At the 90 pounds per acre rate of K, the total titratable acidity

was increased with increased rate of N from 52 to 100 pounds per

acre. However, at 145 pounds per acre rate of K, the total

titratable acidity of fresh fruit increased linearly from 18.0

to 18.7 meq. with an increase in the rate of N. In the April

11 sample, the main effect'of N- rate was quadratic. Increased

rates of N from 52 to 100 pounds per acre, increased the total

titratable acidity from 19.0 to 19.6 meq. A further increase

in the N- rate to 148 pounds per acre reduced the total titrat-

able acidity of fruits to 19.0 meq. In this picking, .the total

titratable acidity of the fruit increased linearly from 18.7

to 19.3 meq. as the K- rate was increased from 35 to 145 pounds

per acre. In the April 18 sample the main effect of K- rate

was also linear. The total titratable acidity increased from

18.4 to 19.6 meq. as the K- rate was increased from 35 to 145

pounds per acre.

An interaction between the rate of N and rate of K was

significant in the April 18 samples. At 35 and 145 pounds per

acre rates of K, increased rates of N from 52 to 148 pounds

per acre resulted in a linear reduction in the total titratable

acidity of the fruit. At the 90 pound per acre rate of K,

however, the total titratable acidity increased from 18.3 to

20.2 meq. with an increase in the N- rate from 52 to 100

pounds per acre. A further increase to 148 pounds per acre N,

resulted in the reduction in the total titratable acidity of

fresh fruit to 18.7 meq. After eight days storage the total










titratable acidity of the fruit harvested on March 25 on plots

receiving KNO3 was significantly greater than plots receiving

K2S04 or KC1. The total titratable acidity of the fruits from

KNO3 plots was 18.9 meq., whereas, in the fruits from plots

receiving either K2SO4 or KC1 the total titratable acidity was

18.0 meq. (Table 37).

Increased rates of K resulted in a significant linear

increase in the total titratable acidity of stored fruits at

all three pickings. In the April 18 picking, an interaction

between K- source and K- rate was significant. When the K-

source was KN03, increased K- rates from 35 to 145 pounds per

acre resulted in a linear increase in the total titratable

acidity of the fruit from 15.4 to 17.7 meq. With K2S04 or KC1

as the source of K, the total titratable acidity was increased

when the K- rate was increased from 35 to 90 pounds per acre.

A further increase in the K- rate was accompanied by a reduction

in the total titratable acidity of the fruit.

Fresh fruits from plots not receiving K, showed a con-

sistent reduction in their total titratable acidity as the

fruiting season progressed. The total titratable acidity of

the fruits from these plots was less as compared to those from

the K treated plots, except in the March 25 picking.

Fruit tissue composition

Total nitrogen -- Treatment effects on the total N con-

tent of fruit from the March 25 picking were not significant

(Table 38). An interaction between K- source and the rate of K

was significant at the April 11 sampling. At 35 and 90 pounds








Table 37. Effect of potassium source and rate of potassium and nitrogen on
acidity of strawberries from March 25, April 11 and April 18, 1966 pickings
eight, four and eight days respectively.


total titratable
after storage for


Rate Total titratable acidity (meq. NaOlI)
Ib/acre March 25 April 11 April 18
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean


52 35 18.4 19.3 17.1 18.3 19.8 18.0 19.1 19.0 .16.6 16.3 15.7 16.2
90 18.4 19.7 18.3 18.8 19.3 19.1 20.1 19.5 16.4 16.1 17.1 16.5
145 18.5 20.3 17.8 18.9 19.6 19.4 18.4 19.1 16.9 17.5 15.9 16.8
Mean 18.4 19.8 17.7 18.7 19.6 18.8 19.2 19.2 16.6 16.6 16.2 16.5

100 35 17.4 17.9 17.5 17.6 17.6 19.2 19.1 18.6 16.2 14.8 17.1 16.0
90 18.0 18.4 18.9 18.4 20.9 21.4 18.4 20.2 17.3 17.3 16.5 17.0
145 18.8 18.6 18.1 18.5 20.0 19.9 20.6 20.2 17.6 17.3 16.7 17.2
Mean 18.1 18.3 18.2 18.2 19.5 20.2 19.4 19.7 17.0 16.5 16.8 16.8

148 35 16.7 17.0 17.7 17.1 17.3 19.0 18.8 18.4 15.0 15.2 16.9 15.7
90 16.8 18.8 17.7 17.8 19.4 20.4 19.5 19.8 17.6 15.9 16.9 16.8
145 18.9 19.7 19.0 19.2 19.5 19.0 21.4 20.0 15.9 17.5 16.8 16.7
Mean 17.5 18.5 18.1 18.0 18.7 19.5 19.9 19.4 16.2 16.2 16.9 16.4

35 17.5 18.1 17.4 17.7 18.2 18.7 19.0 18.6 15.9 15.4 16.6 16.0
90 17.7 18.9 18.3 18.3 19.9 20.3 19.3 19.8 17.1 16.4 16.8 16.8
145 18.7 19.6 18.3 18.9 19.7 19.4 20.1 19.7 16.8 17.4 16.5 16.9
Mean 18.0 18.9 18.0 18.3 19.3 19.5 19.5 19.4 16.6 16.4 16.6 16.5
100 0 18.1 19.4 14.7
Significant treatment effects:


March 25 K rate effect is linear**.
Mean of K2SO4+KCl is less
mean of KN03*'
April 11 K rate effect is linear**.

*Significant at 5% level of P.
**Significant at 1% level of P.


April 18 K rate effect is linear,*.
K2SO4+KC1 vs. KNO3 x K linear*.


than








Table 38. Effect of potassium source and rate of potassium and nitrogen on total nitrogen
content of strawberry fruits from March 25, April 11, and April 18, 1966 pickings.

Rate Total nitrogen (per cent)
lb/acre March 25 April 11 April 18
N K K2SO4 KN03 KC1 Mean K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean


52 35 2.16 2.18 2.05 2.13 1.57 1.73 1.60 1.63 1.24 1.50 1.32 1.35
90 2.26 2.30 2.34 2.30 1.65 1.60 1.98 1.74 1.46 1.58 1.33 1.46
145 2.19 2.22 2.18 2.20 1.-76 1.78 1.66 1.73 1.58 1.44 1.37 1.46
Mean 2.20 2.23 2.19 2.21 1.66 1.70 1.75 1.70 1.43 1.51 1.34 1.43

100 35 2.20 2.30 1.95 2.15 1.87 1.67 1.82 1.79 1.52 1.54 1.52 1.53
90 2.34 1.84 1.35 1.84 1.69 1.72 1.74 1.72 1.60 1.45 1.61 1.55
145 2.16 2.18 2.37 2.24 1.73 1.45 1.51 1.56 -1.46 1.43 1.57 1.49
Mean 2.23 2.11 1.89 2.08 1.76 1.61 1.69 1.69 1.53 1.47 1.57 1.52

148 35 1.89 2.27 2.17 2.11 1.77 1.76 1.84 1.79 1.54 1.73 1.59 1.62
90 2.07 2.11 2.35 2.18 1.75 1.75 1.86 1.79 1.53 1.46 1.53 1.51
145 2.17 2.10 2.11 2.13 2.25 1.75 1.70 1.90 1.52 1.55 1.63 1.57
Mean 2.02 2.16 2.21 2.14 1.92 1.75 1.80 1.82 1.53 1.58 1.58 1.56

35 2.08 2.25 2.06 2.13 1.74 1.72 1.75 1.74 1.43 1.59 1.48 1.50
90 2.22 2.08 2.01 2.10 1.70 1.69 1.86 1.75 1.53 1.50 1.49 1.51
145 2.17 2.17 2.22 2.19 1.91 1.66 1.62 1.73 1.52 1.47 1.52 1.50
Mean 2.16 2.17 2.10 2.14 1.78 1.69 1.74 1.74 1.49 1.52 1.50 1.50
100 0 1.73' 1.69 1.60
Significant treatment effects:


April 11 K2SO4 vs. KC1 x K quadratic*.
N quadratic x K linear*.


April 18 N rate effect is linear**
N linear x K linear*.


*Significant at 5% level of P.
**Significant at 1% level of P.










per acre rates of K, the total N contents of fruits were greater

with the KC1 as compared to K2SO4 as the source of K. At the 145

pounds per acre rate of K, however, fruits from K2S04 had a

higher total N content as compared with KC1. An interaction

between the rate of N and the rate of K was also significant in

the April 11 samples.

Increased rates of N resulted in a significant linear

increase in the total N content of the fruit at the April 18

sampling. The N content increased from 1.43 to 1.56 per cent

as the N- rates were increased from 52 to 148 pounds per acre.

In this picking, an interaction between the rate of N and the

rate of K was also significant. At all three rates of K, in-

creased N- rates produced significant linear increase in the total

N content of the fruit. This increase was greatest at the 35

pounds per acre K- rate, and lowest at the 90 pounds per acre

rate of K (Table 38).

Potassium -- In the March 25 samples, the K content

of fruits from the K2S04 source was significantly greater as

compared to fruits where KC1 was the source of K (Table 39).

Source of K significantly interacted with the rate of K and the

rate of N in this picking. With K2SO4 as the source of K, the

fruit K content was reduced linearly from 2.07 to 1.69 per cent

as the N- rates were increased from 52 to 148 pounds per acre.

With KC1 as the source of K, however, fruit K contents were re-

duced from 1.66 to 1.63 per cent, with increased rates of N from

52 to 100 pounds per acre. A further increase in the N- rate

to 148 pounds per acre increased the fruit K content to 1.67 per

cent.








Table 39. Effect of potassium source and rate of potassium and nitrogen on potassium content
of strawberry fruits from March 25, April 11, and April 18, 1966 pickings.

Rate Potassium content (per cent)
Ib/acre March 25 April 11 April 18
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean


52 35 1.96 1.96 1.49 1.86 1.38 1.62 1.59 1.53 1.93 1.99 1.89 1.94
90 2.11 1.81 1.87 1.93 1.49 1.53 1.49 1.50 2.04 2.09 2.00 2.04
145 2.14 1.82 1.63 1.86 1.63 1.49 1.59 1.57 2.18 2.16 2.01 2.12
Mean 2.07 1.86 1.66 1.86 1.50 1.55 1.56 1.54 2.05 2.08 1.97 2.03

100 35 1.90 2.04 1.32 1.75 1.49 1.59 1.71 1.60 1.83 2.01 2.06 1.97
90 1.71 1.70 1.77 1.73 1.61 1.55 1.59 1.58 2.07 2.05 2.14 2.09
145 1.87 1.70 1.80 1.79 1.59 1.54 1.63 1.59 2.04 2.02 2.16 2.07
Mean 1.83 1.81 1.63 1.76 1.56 1.56 1.64 1.59 1.98 2.03 2.12 2.04

148 35 1.93 1.86 1.66 1.64 1.46 1.59 1.56 1.54 1.79 1.92 1.99 1.90
90 1.94 1.86 1.64 1.81 1.61 1.59 1.62 2.09 2.09 2.05 2.14 2.09
145 1.74 1.76 1.71 1.74 1.53 1.69 1.67 1.63 2.16 2.13 2.14 2.14
Mean 1.69 1.82 1.67 1.73 1.53 1.65 1.61 1.60 2.01 2.03 2.09 2.04

35 1.75 1.95 1.49 1.73 1.44 1.60 1.62 1.55 1.85 1.97 1.98 1.93
90 1.92 1.79 1.76 1.82 1.57 1.58 1.55 1.57 2.07 2.06 2.09 2.07
145 1.92 1.76 1.71 1.80 1.58 1.57 1.63 1.69 2.13 2.10 2.10 2.11
Mean 1.86 1.83 1.65 1.78 1.53 1.58 1.60 1.57 2.02 2.04 2.06 2.04
100 0 1.39 1.45 2.04
Significant treatment effects:


March 25 Mean of K2SO4 is greater than
mean of KCl*-*.
K2SO4 vs. KC1 x N linear*.
K2SO4+KCI vs. KNO3 x K linear-*.

*Significant at 5% level of P.
**Significant at 1% level of P.


April 11 K2SO2+KC1 vs. KNO x K lin
April 18 K rate effect is linear-*.


ear*-*.









Where KN03 was the K- source, fruit K contents were

reduced linearly from 1.95 to 1.76 per cent with an increased

K- rate from 35 to 145 pounds per acre. With K2S04 or KC1 as

K- source, however, the K- rate effect was quadratic. A similar

K- source and K- rate interaction was significant in the April 11

samples.

Although increased rates of K resulted in an increase in

the fruit K levels in all the pickings, the increases were sig-

nificant only at the April 18 picking. Fruit K levels increased

linearly from 1.93 to 2.11 per cent with an increase in the K

supply from 35 to 145 pounds per acre.

It is important to note that the K content of fruit from

plots not receiving K increased as the season progressed. This

increase was from 1.39 per cent at March 25 to 2.04 per cent at

the April 18 sampling.

Calcium -- In the March 25 sample, a decline in the fruit

Ca level with increased rates of K was significant (Table 40).

Fruit Ca levels were reduced from 0.171 to 0.145 per cent with

increased rates of K from 35 to 145 pounds per acre. Fruit Ca

content at the April 11 picking was significantly higher were

K2SO4 was the source of K as compared with KC1. This effect of

K- source was also significant at the April 18 sampling. In

fruits from the April 18 picking an interaction between K-

source and rate of N was also significant. When KCI was the

source of K, fruit Ca levels increased linearly from 0.170 to

0.259 per cent with increased N- rates from 52 to 148 pounds per

acre. When the K- source was K2S04, however, fruit Ca levels








Table 40. Effect of potassium source and rate of potassium and nitrogen on calcium content of
strawberry fruits from March 25, April 11, and April 18, 1966 pickings.

Rate Calcium content (per cent)
lb/acre March 25 April 11 April 18
N K K2SO4 KNO3 KC1 Mean K2S04 KNO3 KCl Mean K2SO4 KNO3 KC1 Mean

52 35 0.203 0.166 0.160 0.176 0.308 0.291 0.272 0.290 0.288 0.220 0.173 0.227
90 0.153 0.142 0.167 0.154 0.255 0.293 0.291 0.280 0.270 0.209 0.181 0.220
145 0.157 0.140 0.135 0.144 0.285 0.297 0.236 0.273 0.237 0.196 0.157 0.197
Mean 0.171 0.149 0.154 0.158 0.283 0.294 0.266 0.281 0.265 0.208 0.170 0.214

100 35 0.145 0.187 0.184 0.172 0.293 0.297 0.246 0.279 0.272 0.231 0.172 0.225
90 0.134 0.123 0.142 0.133 0.289 0.274 0.261 0.275 0.275 0.125 0.211 0.204
145 0.158 0.133 0.151 0.147 0.277 0.254 0.261 0.264 0.266 0.123 0.214 0.201
Mean 0.146 0.148 0.159 0.151 0.286 0.275 0.256 0.272 0.271 0.160 0.199 0.210

148 35 0.156 0.167 0.170 0.164 0.287 0.251 0.284 0.274 0.296 0.176 0.251 0.241
90 0.149 0.174 0.121 0.148 0.286 0.240 0.270 0.265 0.199 0.132 0.251 0.194
145 0.154 0.138 0.138 0.143 0.302 0.281 0.230 0.271 0.196 0.131 0.274 0.200
Mean 0.153 0.160 0.143 0.152 0.292 0.257 0.261 0.270 0.230 0.146 0.259 0.212

35 0.168 0.173 0.171 0.171 0.296 0.280 0.267 0.281 0.285 0.209 0.199 0.231
90 0.145 0.146 0.143 0.145 0.277 0.269 0.274 0.273 0.248 0.155 0.214 0.206
145 0.156 0.137 0.141 0.145 0.288 0.277 0.242 0.269 0.233 0.150 0.215 0.199
Mean 0.146 0.152 0.152 0.153 0.287 0.275 0.261 0.274 0.255 0.171 0.209 0.212
100 0 0.160 0.305 0.315
Significant treatment effects:


April 18 -


March 25 K rate effect is linear**.
April 11 Mean of K2SO4 is greater
than mean of KC1*-".


*Significant at 5% level of P.
**Significant at 1% level of P.


Mean of K2SO4
mean of KC1*.
K2S04 vs. KC1
K2SO4+KC1 vs.


is greater than

x N linear**.
MKNO3 x N linear*.









increased from 0.265 to 0.271 per cent with increased rates of

N from 52 to 100 pounds per acre. A further increase in the N-

rate to 148 pounds per acre, resulted in a reduction in the Ca

level of fruit to 0.230 per cent. With KNO3 as K- source, fruit

Ca content decreased linearly from 0.208 to 0.146 per cent with

increased N- rates from 52 to 148 pounds per acre.

The Ca level in the fruits from plots not receiving K

was higher than those from plots receiving K at all three

samplings.

Magnesium -- Fruit Mg content at the March 25 sampling

was not affected by treatments (Table 41). At the April 11

sampling an interaction between K- source and rate of K was

significant. When the K- source was K2S04, fruit Mg level in-

creased linearly with increased rates of K. With KC1, the Mg

level in the fruit was reduced with increased rates of K. An

interaction between K- source and rate of N was significant at

the April 18 sampling. Where the source of K was K2S04, fruit

Mg content increased with an increase in the N- rate from 52 to

100 pounds per acre. A further increase to 148 pounds per acre

N reduced the Mg content of the fruit. With KC1 as the source

of K, the fruit Mg level was increased with increased rates of

N.

In fruits from plots not receiving K, the Mg content

increased as the season progressed. Whereas in plots fertilized

with K, the fruit Mg level was reduced consistently.








Table 41. Effect of potassium source and rate of potassium and nitrogen on magnesium content
of strawberry fruit from March 25, April 11 and April 18, 1966 pickings.


Rate Magnesium content (per cent x 10-1)
lb/acre March 25 April 11 April 18
N K K2SO4 KNO3 KCl Mean K2SO4 KNO3 KCl Mean K2SO4 -03 KC Mean


52 35 0.230 0.233 0.268 0.244 0.233 0.256 0.255 0.248 0.228 0.201 0.214 0.214
90 0.275 0.283 0.229 0.262 0.231 0.244 0.236 0.237 0.249 0.236 0.226 0.237
145- 0.274 0.268 0.262 0.268 0.246 0.239 0.240 0.242 0.236 0.229 0.232 0.232
Mean 0.260 0.261 0.253 0.258 0.237 0.246 0.244 0.242 0.238 0.222 0.224 0.228

100 35 0.252 0.256 0.195 0.234 0.243 0.249 0.254 0.249 0.209 0.237 0.243 0.230
90 0.270 0.268 0.242 0.260 0.264 0.267 0.242 0.258 0.263 0.236 0.251 0.250
145 0.267 0.241 0.256 0.255 0.249 0.215 0.239 0.234 0.264 0.232 0.232 0.243
Mean 0.263 0.255 0.231 0.250 0.252 0.244 0.245 0.247 0.245 0.235 0.242 0.241

148 35 0.271 0.250 0.270 0.264 0.229 0.231 0.271 0.244 0.229 0.246 0.236 0.237
90 0.259 0.267 0.256 0.261 0.252 0.261 0.230 0.248 0.201 0.231 0.259 0.230
145 0.280 0.270 0.273 0.278 0.262 0.261 0.228 0.250 0.226 0.237 0.265 0.243
Mean 0.270 0.266 0.266 0.267 0.248 0.251 0.243 0.247 0.219 0.238 0.254 0.237

35 0.251 0.246 0.244 0.247 0.235 0.245 0.260 0.247 0.222 0.228 0.231 0.227
90 0.268 0.273 0.242 0.261 0.249 0.257 0.236 0.247 0.238 0.234 0.245 0.239
145 0.274 0.263 0.264 0.267 0.252 0.238 0.236 0.242 0.242 0.233 0.243 0.239
Mean 0.264 0.261 0.250 0,258 0.245 0.247 0.244 0.245 0.234 0.232 0.240 0.235
100 0 0.234 0.242 0.296


Significant
April 11 -
April 18 -


treatment effects:


K2SO4 vs. KC1 x K linear-*.
K2SO4 vs. KC1 x N linear-.


*Significant at 5% level of P.
**Significant at 1% level of P.










Foliar composition

Total nitrogen -- Data for the foliar N level are shown

in Tables 42 and 43. At the March 17 sampling, an interaction

between the source of K and K- rate was significant. Although

the main effect of N- rate was not significant at the January 17

sampling, foliar N contents were significantly increased with

increased rates of N at. March 17, April 18, and May 17 samplings.

At the March 17 sampling, foliar N contents were increased from

3.76 to 3.90 per cent with increased rates of N from 52 to 100

pounds per acre. A further increase in the rate of N to 148

pounds per acre reduced the foliar level of N to 3.81 per cent

(Table 42). At April 18 and May 17 samplings, however, foliar

N contents were increased linearly with increased N- rates (Table

43).

At the April 18 sampling, an interaction between the

source of K and N- rate was significant. Where K2S04 was the

source of K, the foliar N content increased linearly from 3.42

to 3.82 per cent with an increase in the N- rate from 52 to 148

pounds per acre. With XC1 as K- source, however, increasing the

N- rate from 52 to 100 pounds per acre increased the foliar N

content, but a further increase in the N- rate resulted in a

reduction in the foliar N content. An interaction between K-

source and rate of K was also significant at the May 17 sampling.

At the May 17 sampling, an interaction between the rate of N and

rate of K was also significant. At the 35 and 90 pounds per acre

K- rates, increasing the rate of N from 52 to 148 pounds per acre

resulted in a linear increase in the foliar N content. However,










Table 42. Effect of potassium source and rate of potassium and nitrogen on total
nitrogen content of strawberry foliage on January 17 and March 17, 1966.

Rate Total nitrogen (per cent)
lb/acre January 17 March 17
N K K2SO4 KNO3 KC1 Mean K2S04 KNO3 KC1 Mean

52 35 3.63 3.55 3.49 3.56 3.35 3.83 3.73 3.64
90 3.74 3.58 3.55 3.62 3.77 3.83 3.85 3.82
145 3.60 3.62 3.79 3.67 3.78 3.79 3.88 3.82
Mean 3.65 3.58 3.61 3.62 3.63 3.82 3.82 3.76

100 35 3.66 3.75 3.67 3.69 3.90 3.92 3.91 3.91
90 3.45 3.61 3.49 3.52 3.99 3.82 3.91 3.91
145 3.47 3.59 3.57 3.54 3.88 3.94 3.89 3.90
Mean 3.53 3.65 3.58 3.58 3.92 3.89 3.90 3.90

148 35 3.06 3.85 3.70 3.54 3.87 3.93 3.90 3.90
90 3.84 3.67 3.35 3.62 3.98 3.88 3.46 3.74
145 3.52 3.66 3.79 3.66 3.69 3.89 3.80 3.79
Mean 3.47 3.73 3.61 3.61 3.82 3.90 3.72 3.81

35 3.45 3.72 3.62 3.60 3.71 3.89 3.84 3.81
90 3.68 3.62 3.46 3.59 3.88 3.84 3.74 3.82
145 3.53 3.62 3.72 3.62 3.78 3.87 3.86 3.84
Mean 3.55 3.65 3.60 3.60 3.79 3.87 3.81 3.82
100 0 3.79 3.64


Significant treatment effects:
January 17 K2SO4 vs. KC1 x K quadratic*.
March 17 N rate effect is quadratic*.


*Significant at 5% level of P.











Table 43. Effect of potassium source and rate of potassium and nitrogen
nitrogen content of strawberry foliage on April 18 and May 17, 1966.


on total


Rate Total nitrogen (per cent)
lb/acre April 18 May 17
N K K2SO4 KNO3 KC1 Mean K2S04 KNO3 KCI Mean

52 35 3.42 3.j2 3.42 3.32 2.73 2.37 2.89 2.66
90 3.39 3. 8 3.50 3.46 2.89 2.83 2.96 2.89
145 3.45 3. 2 3.46 3.51 2.94 2.93 2.70 2.86
Mean 3.42 3.41 3.46 3.43 2.85 2.71 2.85 2.80

100 35 3.67 3.16 4.03 3.75 2.95 2.84 2.82 2.87
90 3.54 3. 7 4.06 3.59 2.88 2.96 2.91 2.92
145 3.41 3.53 3.36 3.43 2.52 2.77 2.87 2.72
Mean 3.54 3. 2 3.82 3.59 2.78 2.86 2.87 2.84

148 35 3.77 3.55 3.26 3.53 3.14 2.83 3.14 3.04
90 3.83 3.69 3.83 3.78 3.13 3.03 2.92 3.03
145 3.87 3.88 3.63 3.79 2.89 3.11 2.94 2.98
Mean 3.82 3.71 3.57 3.70 3.05 2.99 3.00 3.01

35 3.62 3.41 3.57 3.53 2.94 2.68 2.95 2.86
90 3.59 3.45 3.80 3.61 2.97 2.94 2.93 2.95
145 3.58 3.68 3.48 3.58 2.78 2.94 2.84 2.85
Mean 3.60 3.51 3.62 3.57 2.89 2.85 2.91 2.88
100 0 3.86 3.20
Significant treatment effects:


April 18 -


N rate effect is linear**.
K2S04 vs. KC1 x N quadratic*.
N quadratic x K linear'-*.


May 17 N rate effect is linear**.
K2SO4+KCl vs. KNO3 x K linear**.


*Significant at 5% level of P.
**Significant at 1% level of P.









at the 145 pounds per acre rate of K, increasing the N- rate

from 52 to 100 pounds per acre reduced the foliar N content

from 2.86 to 2.72 per cent, but a further increase in the rate

of N to 148 pounds per acre N increased the foliar N content

to 2.98 per cent.

Potassium -- Foliar content of K at the January 17

sampling was not significantly influenced by treatments (Table

44). However, throughout the remainder of the season, foliar

K levels-we-re--increased- inearly-with increased rates of K

(Tables 44, 45). At the March 17 and May 17 samplings the main

effect of N- rate was quadratic. Foliar K levels in the March

17 samples increased from 1.52 to 1.58 per cent with increased

rates of N from 52 to 100 pounds per acre. At the 148 pounds

per acre rate of N, however, the foliar K level was reduced to

1.55 per cent.

An interaction between the source of K and N- rate was

significant at the March 17 sampling. With K2SO4 as the source

of K, foliar K levels were increased from 1.50 to 1.56 per cent

as the N- rate was increased from 52 to 148 pounds per acre.

Where KC1 was the source of K, foliar K contents were increased

with an increase in the N- rate only to 100 pounds per acre.

Foliar samples from plots not receiving K showed a

consistent reduction in their K levels during the fruiting

season.

Calcium -- At January 17 and March 17 samplings, foliar

Ca levels were reduced linearly with increased rates of K










Table 44. Effect of potassium source and rate of potassium and nitrogen on potassium
content of strawberry foliage on January 17 and March 17, 1966.

Rate Potassium content (per cent)
Ib/acre January 17 March 17
N K K2SO4 KNO3 KC1 Mean .K2SO4 KNO3 KC1 Mean

52 35 1.34 1.47 1.52 1.44 1.52 1.50 1.47 1.49
90 1.51 1.50 1.51 1.51 1.49 1.58 1.50 1.52
145 1.39 1.39 1.50 1.43 1.50 1.57 1.59 1.55
Mean 1.41 1.45 1.51 1.46 1.50 1.55 1.52 1.52

100 35 1.52 1.36 1.47 1.45 1.51 1.51 1.62 1.55
90 1.44 1.49 1.52 1.48 1.49 1.58 1.63 1.57
145 1.48 1.45 1.56 1.49 1.55 1.69 1.62 1.62
Mean 1.48 1.43 1.52 1.47 1.52 1.59 1.62 1.58

148 35 1.45 1.50 1.43 1.46 1.47 1.52 1.45 1.48
90 1.51 1.53 1.51 1.52 1.56 1.56 1.53 1.55
145 1.52 1.54 1.44 1.50 1.65 1.64 1.54 1.61
Mean 1.49 1.52 1.46 1.49 1.56 1.57 1.51 1.55

35 1.99 1.44 1.47 1.63 1.50 1.51 1.51 1.51
90 1.49 1.51 1.51 1.50 1.51 1.57 1.55 1.54
145 1.46 1.46 1.50 1.47 1.57 1.63 1.58 1.59
Mean 1.65 1.47 1.49 1.53 1.53 1.57 1.55 1.54
100 0 1.33 1.32
Significant treatment effects:
March 17 N rate effect is quadratic*.
K rate effect is linear*-.
K2SO4 vs. KC1 x N quadratic**.


*Significant at 5% level of P.
**Significant at 1% level of P.











Table 45. Effect of potassium source and rate of potassium and nitrogen on potassium
content of strawberry foliage on April 18 and May 17, 1966.

Rate Potassium content (per cent)
lb/acre April 18 May 17
N K K2SO4 KNO3 KC1 Mean K2SO4 KNO3 KC1 Mean

52 35 1.36 1.45 1.39 1.40 1.85 2.01 1.78 1.88
90 1.56 1.58 1.45 1.53 1.89 1.90 2.01 1.93
145 1.65 1.51 1.60 1.59 1.85 1.96 2.03 1.95
Mean 1.52 1.51 1.48 1.50 1.86 1.96 1.94 1.92

100 35 1.44 1.38 1.38 1.40 1.74 1.82 1.73 1.76
90 1.58 1.57 1.53 1.56 2.21 2.08 1.92 2.07
145 1.57 1.57 1.56 1.57 2.26 2.01 2.31 2.19
Mean 1.53 1.51 1.49 1.51 2.07 1.97 1.99 2.01

148 35 1.46 1.42 1.35 1.41 1.84 1.77 1.78 1.80
90 1.65 1.54 1.53 1.57 2.08 1.89 1.79 1.92
145 1.60 1.68 1.62 1.63 1.97 1.95 2.03 1.98
Mean 1.57 1.55 1.50 1.54 1.96 1.87 1.87 1.90

35 1.42 1.42 1.37 1.40 1.81 1.87 1.76 1.81
90 1.60 1.56 1.50 1.55 2.06 1.96 1.91 1.98
145 1.61 1.59 1.59 1.60 2.03 1.97 2.12 2.04
Mean 1.54 1.52 1.49 1.52 1.97 1.93 1.93 1.94
100 0 1.03 1.40
Significant treatment effects:
April 18 K rate effect is linear-"*.
May 17 N rate effect is quadratic*.
K rate effect is linear**.
N quadratic x K linear'x-.


*Significant at 5% level of P.
**Significant at 1% level of P.








(Table 46). At the January 17 sampling the reduction was from

0.597 to 0.558 per cent. At the March 17 sampling, foliar Ca

content was reduced from 0.833 to 0.799 per cent as the rate of

K increased from 35 to 145 pounds per acre. In the April 18

samples, the foliar Ca content was reduced linearly from 1.16

to 0.97 per cent, with increased rates of N (Table 47). At the

May 17 sampling the K- source effect significantly interacted

with the rate of K. This interaction was difficult to interpret.

Over the sampling period the Ca content of the foliage

from plots not receiving K was greater than the foliar Ca levels

in the plots fertilized with K. In general, an increase in the

foliar Ca content occurred throughout the fruiting season.

However, in the May 17 samples, the Ca level dropped below those

in the April 18 samples. This was true in both, plots not fertil-

ized with K as well as those fertilized with K.

Magnesium -- At January 17 sampling, the foliar Mg

content was significantly greater where KCl was the source of

K as compared with K2SO4 (Table 48). An interaction between

K- source and N- rate was also significant. The foliar Mg

content increased with increased N supply wherethe K- source

was K2SO4, but decreased where KC1 was the source of K. As the

fruiting season advanced the main effect of K- rate became sig-

nificant. At the April 18 sampling the foliar K level was re-

duced from 0.690 to 0.656 per cent as the K- rate was increased

from 35 to 145 pounds per acre (Table 49). At the May 17

sampling, treatment effects were not significant.




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