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Copyright 2005, Board of Trustees, University
Agricultural Research & Education Center
SIFAS, University of Florida
AREC Bradenton Research Report GC1980-10 December 1980
EFFECT OF FERTILIZERS AND. WITHIN WROi-PENtSACING
ON TOMATO FRUIT SIZE AND YIELD
A. A. Csizinszky
The price of fresh market tomatoes depends on supply and demand. However, re-
gardless of the market fluctuation, larger size tomatoes always command a relatively
higher price than smaller ones. For example, unit prices (30 lb cartons) of mature
green, 85% or more U.S. No. 1 quality tomatoes at two selected dates during the 1979
fall and 1980 spring seasons were as follows:
Date _P 0oly 10 'A un SY-sv'I
Size Dec. 3 1979 Ma 2, 198 0 A!n -S
5x 6 7-8.0 12.0 1861 .o 34
6 x 6 6-7.0 10.0
6x 7 4-5.0 8.0 A;L ,I 1 3lIlH
7x 7 3-3.5 6t0
(FLORIDA TOMATO-POTATO REPORT, VOL. 5,
NO. 10, and VOL. 5, NO. 52)
It is important, therefore, to investigate which factors influence tomato.size
and yield, and, more importantly, what can the growers do to improve both fruit size
There are certain aspects of agricultural production which are beyond anyone's
control, namely: weather, sudden occurrence of new plant pests, and growing season.
All of these are known to influence fruit set, size, shape, anta quality.
There are several other factors over which the growers have control and can
1. The selection of cultivars
2. Fertilizer programs
3. Within-row plant spacing
4. Time elapsed between pickings within the crop season
In this report the importance of cultivar (cv.), fertilizer program, within-row
plant spacing and season for fruit size and yield of staked, fresh market tomatoes
will be discussed. Since growers use various numbers of plant beds between lateral
irrigation furrows, amount of fertilizer applied and tomato yield in this paper will
be given on a 1000 linear row ft, rather than on a per acre (A) basis.
1. Effect of cultivar on fruit size and yield. Each tomato cultivar has its
own genetical constitution which determines, among other things, the growth habit
of plant and the shape, size and color of its fruit. Under "equal" growing condi-
tions the various cultivars will perform according to their inherited potential.
depending on their genetic make-up. The influence of cultivars on fruit size and
marketable yield is illustrated with data from the 1980 spring season on Table 1.
In this case, the cultivars 'Flora-Dade,' 'Duke,' and 'FTE 12' were grown in repli-
cated trials in mulched beds with 4.5 ft centers at 20 in. within-row plant spacing.
All 3 cultivars received 5.2 lb N, 19 lb PP20, and 2.5 lb K,0 per 1000 ft row as
starter fertilizer (bed mix), then an 18-0-25 + 2 analysis fertilizer was banded on
the shoulders of the plant bed at a rate of 39 lb N, 19 lb P0O, and 50 lb K20 per
1000 ft row. Fritted micronutrients were applied with the superphosphate in the
starter. The first 3 side shoots on each plant were pruned at first tying. Fruit
was picked 3 times during the season at 7 day intervals, size graded, and number
and weight of fruit for each grade was taken. 'Flora-Dade,' a firm fruited cultivar,
had smaller fruit than the new F hybrid cultivars 'Duke' and 'FTE 12,' although the
number of marketable fruit per plant was not significantly different from the two
F hybrid cultivars (Table 1). In earlier trials in the Manatee-Ruskin area and at
the AREC-Bradenton, the cv 'Flora-Dade' always had a smaller % of fruit in the extra
large and large size grades than the F hybrid cultivars.
2. Effect of fertilizer quantity on fruit size and yield. Type and quantity
of fertilizers to be used for the tomato crop also can be regulated by the growers.
During the past several seasons at the AREC-Bradenton, the application of lower
fertiizef quantities either resulted in slightly larger tomato fruit size or rio
difference at all, When compared to tomatoes grown with higher amounts of fertili-
zers (Table 2). Total marketable yield was alWays higher W'th the lower fertilizer
application, This relationship was true, regardless of cultivars used in the exper-
iments. Other researchers in different geographical areas of the state also found
similar correlations between tomato yield, fruit size and fertilizer quantities.
The application of larger amounts of fertilizer resulted in heavier plants with
larger stem diameters and more vigorous growth (data not presented here). Thus, in
the eyes of a viewer, a heavily fertilized tomato field looks very impressive, but
the yield and fruit size can be poorer than that from a field which received less
3. Effect of within-row plant spacing on fruit size and yield. In the exper-
iments, greater in-row spacing between plants resulted in larger fruit size through-
out the years (Table 3). Marketable yield, however, was always higher at closer
plant spacing. Thus the number of plants per acre, regulated by planting distance
within the row, appears to be a very important factor both for fruit size and for
marketable yield. Larger numbers of plants per acre require a higher input of
materials (transplants, stakes, pesticides, etc.) and labor. Growers have to decide
whether higher production costs and somewhat smaller fruit size at the higher plant
population would offset a significantly higher marketable yield.
In a series of experiments conducted in 1979 and 1980, we investigated the
effect of in-row plant spacing and fertilizer quantities on fruit size and yield,
when plants receive equal amounts of fertilizers at the various in-row plant
There were 2 in-row plant spacings and 3 fertilizer treatments in a randomized
block design, replicated 4 times (Table 4). At the Ix fertilizer treatment, 5.6 lb
N, 2.0 lb P^O and 2.5 lb K 0 were applied per 1000 linear ft as starter fertili-
zers, then th 'Flora-Dade' tomatoes on a per plant basis received 4 oz of 18-0-25 + 2
(banded) and 0.67 oz of 20% superphosphate (mixed in the soil). In the 2x and 3x
fertilizer rates, the starter fertilizers were the same, but the 18-0-25 + 2 and the
additional superphosphate was increased to 2 and 3 times the amount applied in the
lx treatment, respectively. Fruit was picked 3 times during the season.
In the spring of 1979, fruit size was best at the 30 in. in-row plant spacing
with the low (Ix) fertilizer treatment, followed by the low fertilizer treatment
(lx)at 18 in. within-row plant spacing (Table 5). Regardless of plant spacing,
best fruit size was with the lowest quantity of fertilizer. Marketable yields were
higher at closer plant spacing because of the larger number of plants, but increasing
the amount of fertilizer did not result in higher yield at either of the 2 plant
spacings. Number of fruit harvested did not show a clear pattern. At 18 in. plant
spacing, fruit numbers were somewhat higher at the Ix fertilizer treatment, while
at 30 in. plant spacing, fewer fruit were harvested with the lowest amount of fer-
In the fall of 1979 and in the spring of 1980, the same fertilizer experiment
was repeated but only at 30 in. plant spacing. There were 3 pickings during the
harvest season, fruit was separated according to size, counted and weighed. Regard-
less of the season, fruit size was best with the lowest (lx) fertilizer application
(Table 6). Marketable yields were lower in the fall season due to the smaller num-
bers of fruit harvested. Yield per 1000 ft-row in both seasons was not statisti-
cally different with the 3 fertilizer treatments. The % of extra large and large
fruit in the fall was significantly higher with the lowest (Ix) fertilizer treat-
ment and in the spring with the lx and 2x fertilizer treatment. In these experi-
ments, as in previous seasons, the application of large amounts of fertilizers did
not result in better fruit size and yield or higher % of extra large and large size
4. Effect of season on tomato fruit size and yield is
In 1978, fruit size was better in the fall season, while in
ger size fruit in the spring. Similar observation was made
on marketable yield. The spring yields, however, had shown
the fall yields.
not consistent (Table 7).
1979, tomatoes had lar-
on the seasonal effect
greater variation than
In Summary, lower amounts of fertilizers and greater within-row plant spacing
resulted in larger size tomato fruits. Total marketable yields did not increase
with increasing amounts of fertilizer application. However, caution should be
exercised with the smaller amounts of fertilizer application in the fall, when
heavy rains early in the season may leach the fertilizer from the plant beds in
fields with poor drainage. In these lands, slightly higher amounts of fertilizers
should be used, or the land should be properly graded to facilitate rapid removal
of excess water.
1. Csizinszky, A. A. 1980.
plant spacing in two and
Soc. 93:(in press).
Response of tomatoes to fertilizer rates and within-row"
four row production systems. Proc. Fla. State Hort.
2. Csizinszky, A. A., and D. J. Schuster. 1980.
tomatoes to reduced input of fertilizers and
HortScience 15:379. (Abstract)
Response of staked, fresh market
insecticides in Florida.
3. Everett, P. H. 1971. Evaluation of paper and polyethylene coated paper mulches
and fertilizer rates on tomatoes. Proc. Fla. State Hort. Soc. 84:124-128.
4. Everett, P. H. 1976. Effect of nitrogen and potassium rates on fruit yield
and size of mulch-grown staked tomatoes. Proc. Fla. State Hort. Soc. 89:
5. Geraldson, C. M. 1963. Quantity
yields and quality of tomatoes.
6. Marlowe, G.
and balance of nutrients required for best
Proc. Fla. State Hort. Soc. 76:153-158.
A., Jr., R. T, Montgomery, M. T. Pospichal, and D. J. Schuster.
growers using too much fertilizer in the full bed mulch system?
Npw1pttPr Fah 1Q7Q
Table 1. Effect of variety on tomato fruit size
and yield. Spring 1980-
No. of %- of
Fruit fruit Yield per XLge &
s4qz per 1000,t- large
Variety (oi) plant 6ow (1b) fruit
Floradade 4.42 56 280 66
Duke 5.30 5 1,1120 82
FTE 12 5.3 5 11,640 86
Z20 in. within-row spacing
Table 2. Effect ot fertilizer quantity on tomato fruit size
treatment 1970y 1979x 1980W
Low Fruit size, oz 4.80 5.00 4.83
Yield/1000 ft-row, lb 4,300 7,270 8,050
High Fruit size, oz 4.57 5.10 4.73
Yield/1000 ft-row, lb 4,000 6,880 6,300
zLow: 42 lb N, 16 lb P205, 5' lb K20/1000 ft-row.
High: 60 lb N, 16 Ib P205, 78 lb K20/1000 ft-row.
CV: Walter; XCv: Flora-Dade; wSpring season only.
Table 3. Effect of in-row plant spacing on tomato fruit size
(inches) 1978z 1979 1980yx
18 Fruit size, oz 4.75 4.97 4.42
Yield/1000 ft-row, lb 4,400 7,730 9,280
30 Fruit size, oz 4.85 5.28 4.83
Yield/1000 ft-row, lb 3,790 6,420 6,910
ZCv: Walter; YCv: Flora-Dade; XSpring
Table 4. Amount of nutrients applied at various
in-row spacing, Spring 1979.
Fertilizer N P205 K20
treatment lb/1000 ft-row
18 in. plant spacingz
1xY 35.6 7.6 44.2
2x 65.6 13.2 85.8
3x 95.6 18.7 127.5
36 in. plant spacing
1xY 23.6 5.4 27.5
2x 41.6 8.7 52.5
3x 59.6 12.0 77.2
5.6 lb N, 2.0 lb P205 and 2.5 lb K20/
Ylx = 4 oz 18-0-25 + 2 and 0.67 oz superphosphate/
plant at both in-row plant spacings
Table 5. Effect of fertilizer treatment and in-row
plant spacigg on fruit size and yield,
Fruit Yield per No. of fruit
Fertilizer size 1000 ft-row per 1000 ft-row
treatment (oz) (lb) (xlO00)
18 in. plant spacing
Ix 5.58 8,750 25.1
2x 4.98 7,310 23.5
3x 5.24 7,790 23.8
36 in. plant spacing
lx 6.06 6,400 16.9
2x 5.46 6,450 18.9
3x 5.46 6,245 18.3
Table 6. Effect of fertilizer
size and yield .
treatment on fruit
No. of % of
Fruit Yield per fruit XLg & Lg
Fertilizer size 1000 ft- per 1000 size
treatment (oz) row (lb) ft-row fruit
lx 4.76 4,760 16.0 67
2x 4.54 4,200 14.8 61
3x 4.71 4,360 14.8 65
Ix 4.90 7,780 25.4 65
2x 4.76 7,560 25.4 64
3x 4.62 6,860 23.8 61
ZCv: Flora-Dade, 30 in. in-row spacing.
Table 7. Effect of season on tomato fruit size and
19782 1979Y 1980Y
Fruit size, oz 3.99 5.06 4.83
Yield/1000 ft-row, lb 3,930 9,430 7,700
Fruit size, oz 5.34 4.80
Yield/1000 ft-row, Jb 4,670 4,710 --
ZCV: Walter; YCv:. Flora-Dade.