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Group Title: Research Report - University of Florida Institute of Food and Agricultural Sciences , Central Florida Research and Education Center ; 87-01
Title: Effect of fertilizer rate and plant density on yield and head weight of lettuce
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 Material Information
Title: Effect of fertilizer rate and plant density on yield and head weight of lettuce
Series Title: Research Report - University of Florida Institute of Food and Agricultural Sciences , Central Florida Research and Education Center ; 87-01
Physical Description: Book
Language: English
Creator: Forbes, Richard Brainard
White, J. M.
Publisher: University of Florida, Institute of Food and Agricultural Sciences, Central Florida Research and Education Center
Publication Date: 1986
 Record Information
Bibliographic ID: UF00075883
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 122930834

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida







c-? i Central Science
cI Library
I University of Florida
Institute of Food and Agricultural Sciences OCT 23 198
CENTRAL FLORIDA RESEARCH AND EDUCATION C NTER
Sanford, Florida University of FIo0

Research Report SAN 87-01 August 196

EFFECT OF FERTILIZER RATE AND PLANT DENSITY
ON YIELD AND HEAD WEIGHT OF LETTUCE

R. B. Forbes and J. M. White

Experiments were carried out during the 1975-76 vegetable season to
determine the effects of different fertilization rates and plant
spacings on head lettuce on this Center's farm at Sanford.

Materials and Methods

Experimental plots for the fall 1975 trial were located on
Immokalee fine sand in Field F. The 1976 spring planting was on Manatee
fine sand in Field A. Head lettuce cultivar Great Lakes was used in
both plantings. Plots consisted of 5' wide beds with 2 rows 30" apart
and 20' long for a plot area of 100 square feet or 0.0023 A. A preplant
fertilizer application of 2000 lb/A of 5-5-8-2 (N-P 0 -K 0-M 0)
fertilizer was applied to all plots in the fall experiment a the beds
were being prepared. In the spring planting, 500 lb/A of 5-5-8-2 was
applied as beds were made. In both cases, the remainder of the
fertilizer required to make up the fertilizer treatments was applied as
side-dressings with a 10-4-10-3 mixture.

Lettuce in the fall planting was direct-seeded on September 30,
1975, then thinned to desired stand, and harvested November 18 and 24,
1975. The spring planting was grown from transplants set in the field
January 15, 1976, and harvested March 15, 1976. Soil samples were taken
for information on soil fertility levels. Sample preparation and
determination of pH, soluble salts, and nitrates were done at
CFREC-Sanford. Extractable nutrients were determined at Gainesville by
the IFAS Soil Testing Laboratory.

Results and Discussion

Treatments and yields are given in Tables 1 and 2. In the fall
planting, the high fertilizer rate (225 lb/A N, etc.) produced
significantly greater yields, both total and marketable, and a higher
average head weight than the lower rate (150 lb/A N). Plant spacing had
no significant effect on the total or marketable yields, but did affect
the average head weight. The 12" spacing was better than 9".

In the spring planting, there were no significant differences in
head weight. Fertilizer rate made no difference in yields, however, the
percentage of marketable heads was greater in plots with the low (150
lb/A N) rate of fertilization. Spacing proved important with the 12"
spacing between plants producing better yields than 18".










The interaction between fertilizer rate and plant spacing did not
prove significant in either the fall or the spring trials.

Soil fertility levels are shown in Table 3 for both experiments.
In the fall planting, soil samples were taken only at harvest. The
effects of the fertilizer treatments show a lower pH for the higher
fertility rate and also higher residual N, salts, Mg, and K. There was
little difference in Ca or P, with both in the adequate to high range
regardless of treatment.

The spring planting was sampled soon after transplanting, before
the fertilizer treatments were begun, and again at harvest. These
samples also show the acidifying effects of the fertilization on soil
pH. The higher fertilization lowered soil pH by a whole pH unit. The
overall level of nutrients in the spring experiment, even in the "Low"
fertilizer treatment, was higher than in the fall experiment, perhaps a
reason for the lack of response to the high fertilizer treatment in the
spring. At harvest, nitrates were high in all treatments, soluble
salts, and K were higher in the high fertilizer plots, while Ca, Mg, and
P showed little difference between treatments.

In summary, the experiments showed higher marketable yields with
the higher fertilizer rate in the fall planting, but not in the spring.
The 12" spacing within the row was better than either 9" or 18". The
weight per head averaged 1.49 Ib in the spring compared to 1.27 lb in
the fall planting.









Table 1. Head lettuce yields and head weight from fertilizer rate and
plant spacing trial, Fall 1975.


Treatments

Rate Spacing Total yield2 Marketable yield2 Weight/head2
-inches- ------------cwt/A------------- ----b----

low 12 94 82 1.13

high 12 120 104 1.55

low 9 85 61 1.02

high 9 128 104 1.38

LSD 0.05 43 40 0.18

Summary, Analysis of Variance

Factor: F value F value F value

Fertilizer rate 6.12*3 5.93' 40.93***

Plant spacing <1(NS) <1(NS) 5.38*

Interaction:
Rate x spacing <1(NS) <1(NS) <1(NS)


Fertilizer rates: lb/A N P205 K20 MgO

low 150 120 210 55

high 225 165 300 80

2Yields and head weights are averages of 6 replications.

3, **, *** denote significance at 0.05, 0.01, and 0.001 levels,
respectively.










Table 2. Head lettuce yields and head weight from fertilizer rate and
plant spacing trial, Spring 1976.


Treatment

Rate2 Spacing
-inches-

low 12

high 12

low 18

high 18

LSD 0.05

Summary, Analysis

Factor

Fertilizer rate

Plant spacing

Interaction:
Rate x Spacing


Total1

yield
-cwt/A-

127

148

104

96

43

of Variance:

F value

<1(NS)

6.90*


<1(NS)


Marketable

heads
--$--

31.6

25.6

33.4

29.6

7.3





4.97*3

1.47(NS)


<1(NS)


Marketable

yield
-cwt/A-

82

73

60

51

17



F value

2.78(NS)

14.12"*


<1(NS)


Weight/head
--lb--

1.53

1.38

1.53

1.53

(NS)



F value

<1(NS)

<1


<1(NS)


1Yields and head weights are averages

2Fertilizer rates: lb/A N P205

low 150 90
high 225 135

3, *, *** denote significance at 0.
respectively.


of 6

K20

180
270

05, 0.


replications.

MgO

50
75

01, and 0.001 levels,










Table 3. Soil fertility levels, lettuce fertilizer rate and plant spacing
trials.


Extractable nutrients_
Sample Soluble
description pH NO salts Ca Mg P K


Fall trial ------- ---- ppm-----------
F:16-17 at harvest

Low, 12" 5.7 Low 364 618 88 15 54

High, 12" 5.5 Med. 588 618 98 14 77

Low, 9" 5.8 Low 336 635 84 13 48

High, 9" 5.4 M-High 770 658 99 15 80

Pre-fertilization samples A:41-43.5, January 27, 1976

East half 6.9 M-Low 504 720 145 86 52

West half 6.6 Low 392 635 85 56 46

A:41-43.5 at harvest

Low, 12" 6.0 High 840 620 185 83 128

High, 12" 5.8 High 1050 620 185 80 188

Low, 18" 6.0 High 840 620 175 65 118

High, 18" 5.7 High 1120 620 215 72 238


Extracted with ammonium acetate at pH 4.8 at the IFAS Soil Testing
Laboratory.




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