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FLAG IFAS PALMM UF



Annual rice field day
ALL VOLUMES CITATION SEARCH THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00054448/00002
 Material Information
Title: Annual rice field day
Series Title: Belle Glade EREC research report
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Belle Glade AREC
Belle Glade EREC (Fla.)
Publisher: University of Florida, Institute of Food and Agricultural Sciences, Cooperative Extension Service, Agricultural Research and Education Center.
Place of Publication: Belle Glade FL
Creation Date: 1982
Frequency: annual
regular
 Subjects
Subjects / Keywords: Rice -- Field experiments -- Periodicals -- Florida   ( lcsh )
Rice -- Diseases and pests -- Periodicals -- Florida   ( lcsh )
Rice -- Periodicals -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
serial   ( sobekcm )
 Notes
Dates or Sequential Designation: Began 1978?
Dates or Sequential Designation: Ceased in 1991 or 1992.
Issuing Body: Prior to 1984 this was issued by the Agricultural Research and Education Center (Belle Glade, Fla.), which changed its name to the Everglades Research and Education Center.
General Note: Description based on: 4th (1981); title from cover.
General Note: Latest issue consulted: 11th (1991).
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 40942624
lccn - 2006229205
System ID: UF00054448:00002
 Related Items

Table of Contents
    Copyright
        Copyright
    Title Page
        Title Page
    Table of Contents
        Table of Contents
    AREC rice research program results ( G. H. Snyder )
        Page 1
        Page 2
        Page 3
        Page 4
    Carbohydrate availability during grain filling in rice (D. B. Jones )
        Page 5
        Page 6
        Page 7
        Page 8
    Rice fertilization management (D. M. Brandon )
        Page 9
        Page 10
        Page 10a
        Page 10b
        Page 11
        Page 11a
        Page 11b
        Page 12
        Page 13
    Herbicides for weed control in rice ( J. A. Dusky )
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
    Effect of rice nutrition on disease development ( J. P. Jones )
        Page 20
    Appendix
        Page 21
        Page 22
        Page 23
Full Text





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








BELLE GLADE AREC RESEARCH REPORT EV-1982-3


UNIVERSITY OF FLORIDA



INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES

COOPERATIVE EXTENSION SERVICE








FIFTH ANNUAL


RICE FIELD DAY


AGRICULTURAL RESEARCH

AND

EDUCATION CENTER



BELLE GLADE, FL


JULY 22, 1982


5.0


30
240

0
0-
p 20




00


500 1000 1500 2000
AMOUNT OF CHEMICAL APPLIED PER ACRE






RICE FIELD DAY

Agricultural Research and Education Center
Belle Glade, Florida

July 22, 1982

Kenneth D. Shuler, Presiding
Palm Beach County Extension Agent

Time Page

3:00 All Registration

8:30 Helcome Remarks

8:40 1981 AREC Rice Research Program Results 1
G. II. Snyder

9:00 Carbohydrate Availability During Grain Filling in Rice 5
D. 0. Jones

9:20 Rice Fertilization managementt 9
D. .1. Brandon

9:50 Break
10:10 Rice Fertilization Management (Continued)
D. ?1. Brandon

10:40 Heed Control in Rice 14
J. A. Dusky
11:00 Effect of Rice lNutrition on Disease Development 20
J. P. Jones
11:30 AREC Rice Field Tour

12:15 PH Dutch Treat Lunch

1:15 Tour of Glades Area Rice Field and Rice Drying and Millinq
Facilities


Appendix A




(1)
1981 AREC RICE RESEARCH PROGRAM RESULTS
G.H. Snyderl

Rice research conducted by the AREC-Belle Glade staff during 1981 included such
factors as 1) varieties, 2) nitrogen fertilization, 3) calcium silicate slag,
4) planting dates, 5) seedling chlorosis and 6) weed control. The latter subject
is covered elsewhere in this field day report.
The research program was substantially augmented by the donation of two pieces
of equipment during the past year. A research plot combine was donated to the AREC
by the Florida Rice Council, a newly formed organization of Everglades area rice
growers. The combine received was a Suzue Model CP 730C, a popular type used by
rice researchers in the southeastern states and described in several scientific
papers. Busch Agricultural Resources, Inc., a division of Anheuser-Busch, donated a
Kincaid 6-row research plot rice planter. The value of this planter to our research
program was proven repeatedly as we seeded our 1982 trials. We sincerely appreciate
these donations to the rice research program.
Along with the Palm Beach County Cooperative Extension Service, the AREC pre-
pared a display on Everglades rice production for the 1981 South Florida Fair in
West Palm Beach. This display featured the research plot combine, sacks of rice
provided by New Haven Sugar and Rice, and several posters discussing rice production
in the Everglades. In response to questions about the water needs of rice raised by
some of the viewers of this display, the information in Appendix A at the conclusion
of this report was prepared.
Trials Involving Varieties, Nitrogen, Silicon and Planting Dates
Varieties
Five variety trials were conducted in 1981; three at the AREC and two on area
farms. Two of the trials at the AREC involved nitrogen and slag variables. In all


IGeorge H. Snyder is Professor, AREC-Belle Glade, University of Florida




(2)
trials the seeding rate was to plant one seed/cm in the row, and the row spacing was
25 cm, except that the variety Belmont was planted 25% more densely in the row be-

cause of reported problems with seedling vigor. The plots were hand harvested and
a ratoon crop was obtained from the February planting at the AREC. The results of
these trials are presented in Table 1. Consistent with trials in previous years, the
variety Lebonnet provided the highest grain yield of the long grain varieties tested.
It yielded about 18% higher than Labelle. The semi-dwarf variety Belmont, which

should be very resistant to lodging, provided yields statistically equivalent to
Lebonnet in 3 of the 5 plant crop trials. Yields from the medium grain variety Mars
were statistically equivalent to those of Lebonnet in all 5 trials. The medium
grain variety LAll0 produced the highest yields of all varieties in the one trial
in which it was included. However, this variety is not of sufficient quality to be
accepted as a food rice in the U.S. Lebonnet outyielded the other varieties used
in the ratoon crop test.
Planting Dates
There was no consistent effect of planting date on yield for the 1981 AREC

trials. Yields of Labelle and Mars were approximately the same for all three dates,
whereas those of Belmont and Lebonnet appeared to fall off for the April date.
Nitrogen Fertilization
Consistent with observations in previous years, nitrogen fertilization at and

beyond panicle initiation increased grain yield. However, the ratoon crop yield
was reduced by nitrogen, an effect also observed in 1980. Since the same plots that
received nitrogen in the plant crop also received it for the ratoon crop, it is not
possible to determine which fertilization is responsible for the reduced ratoon crop
yield.
Calcium Silicate Slag
There was no significant effect of calcium silicate slag applications in 1980
on rice yields in the 1981 tests at the AREC. In general over the last three years




(3)
of testing at the AREC, yield responses to slag have been small and inconsistent.
It has been fairly consistently noticed, however, that rice in slag treated plots
matures 2-5 days later than in check plots.
Work with sugarcane has shown responses to slaq are more likely in the more

acid organic soils distant from Lake Okeechobee. The soil in the AREC rice re-

search area has a near neutral pH. One test was conducted on the Brida farm about

20 miles east of Belle Glade in soil with a pH of 4.9. In this trial calcium
silicate slag was applied to one end of each of 9 plots at the rate of 20 t/ha.
The rough rice yield of Lebonnet in this test was 3461 and 4605 kg/ha for check
and treated plots, respectively, in the plant crop, and 1928 and 2329, respectively,
in the ratoon crop. The plant crop rice was taller in the slag treated areas and
lodged in 3 of the 9 treated plots.
Seedling Chlorosis
Work conducted in 1981 was summarized in the 1981 Fourth Annual Rice Field Day

Report (pg. 1-4 to 1-6). Our conclusions remain the same: 1) areas subject to
seedling chlorosis can be predicted by a soil test which measures the total iron
concentration of the soil, 2) seedling chlorosis can be prevented by drilling
50-150 kg/ha of ferrous sulfate with the seed (the exact rate depending upon the
predicted or historical severity of the problem in the soil in question), 3) broad-
casting the same rate of ferrous sulfate will have little impact on the problem and
4) post emergence correction of seedling chlorosis is very difficult. Flooding is
the only suggested corrective measure, but it probably will result in moderate to
appreciable stand reductions.




(4)

Rough rice yields (kg/ha at 12% moisture) in 1981 trials at AREC-Belle Glade
and area farms for various planting dates.


Feb. 16
Plant Ratoon


6772b
7686a
6019c
7431a


2282b
2825a
1801c
2035bc


AREC-BELLE GLADE
March 18 April 16


6770b
7298ab
6158c
7704a
7051b
6855b
7156ab
6941b


5681c
6571a
6244b
7209a


Seminole
(Shawano)
March 24


7211ab
7566ab
6504b
6739b
6478b
8077ab
7865ab
8499a


G & W
(Hest Farm)
April 9


4390bcd
5264bc
4216cde
5467b
3819de
5578ab
3239e
4222cde
4760bcd
6568a


Main Effect

-N
/N
-Slag
/Slag


Means

6388*2282*
7533 2102
6995 2140
NS NS
6940 2249


Nitrogen applied at 30 kg/ha from urea at the time of panicle initiation and
7-10 days later. For ratoon crop N applied at 30 kg/ha after plant crop
harvest and again 7-10 days later. Calcium silicate slag applied at 20 T/ha
in 1980.

***, NS refer to statistical significance at 0.01 or Not Significant, respectively.


Variety


Belmont
Lebonnet
Labelle
Mars
Nortai
S-201
M-9
L-201
Newrex
LAI10


6129,*
6762
6429NS
6463




(5)



CHANGES IN AVAILABLE CARBOHYDRATES
DURING GRAIN FILLING III RICE

D.B. Jones1

Yield development of a rice crop is a complex process influenced by a multi-
tude of factors. One of the most critical factors is the inherent yielding abil-
ity of the rice variety being grown. Improvements in yielding ability of rice
varieties in recent years can be attributed largely to correcting deficiencies and
to better structural characteristics of the plant. These deficiencies are suscep-
tibility to diseases, insects, and various environmental conditions. The principal
structural improvements being worked on included reduced plant height, greater
straw strength and more erect leaves for increased light interception.

Although further improvements are certain to come from disease and insect re-
sistance as well as better plant types, long-range improvements must come from more
efficient physiological processes within the plant. In the absence of pests and
nutritional limitations, yields are conditioned by the interaction between gene-

controlled physiological processes and the physical environment.
Yield ceilings may be limited by the photosynthetic processes, by the trans-
port system within the plant, and/or by the storage capacity of the panicle. Rice
breeders need to know where the limitations exist in order to devise a selection
process for their removal. This study was intended to identify physiological yield
limiting processes during the grain filling period,

The carbohydrate content of vegetative and reproductive parts of the rice
plant was determined during grain filling under full sunlight and partial shading.

David B. Jones is Assistant Professor, AREC-Belle Glade, University of
Florida.




(6)


The objective was to determine the interactions of source (carbohydrate production)
and sink (storage capacity) as related to the components of yield. Rice plants
were sampled at weekly intervals beginning at early flowering and continuing

through maturity. Plant parts were separated and analyzed to determine the con-
centrations of free sugar and starch of the parts throughout grain filling. Shade
cloth that reduced the incident solar radiation by 46% was installed over plots at
the early flowering stage. Shading had no apparent effect on mean panicle weight,
100-grain weight or percent filled grains per panicle (Table 1). No significant
difference was detected in the free sugar concentration of the combined plant parts

between the full sun and shade treatments, while there was significant difference
in the starch concentration. The internodes were the major contributing part of
this difference in starch concentration between the two treatments. Sample date
had a highly significant effect on free sugar and starch concentration of plant
parts over the sampling period.
Plants parts were significantly different in sugar and starch concentrations
and their significant interaction with sample date indicated their changing roles
as sources, sinks or both over the grain filling period. Starch concentrations in
the vegetative organs rapidly increased soon after flowering but declined during
rapid grain filling, indicating an inability of current photosynthesis to meet the
demand for their use during the later period.
Plants in both the sun and shade treatments had a net increase in stored starch in
the vegetative organs over the period of 6 to 34 days after early flowering
(Table 2), suggesting an overall excess supply of carbohydrates available for
grain filling. Therefore, under conditions of this experiment, it appears thai:
yield increases should be realized by breeding for increased storage capacity of
the rice plant.




(7)





Table 1. Characteristics of rice panicles grown under full and reduced
sdn during the grain filling period.

Characteristic Full sun Reduced sun

Mean panicle weight (g) 1.57 1.51
Grain weight per panicle (g) 1.36 1.36

100-grain weight (g) 2.51 2.48
Florets per panicle 80 78
Filled grains per:paniCle 54 55

Percent filled grains 67.5 70.5










Table 2, Total starch content of the vegetative parts (other than the panicle)
of the rice plant during grain filling.


Days after Total Starch Net Increase
early flowering starch concentration Change 6-34 days

9 -------------------% --- ------

Full sunlight

6 3.53 13,26
73.1

20 6.11 21.19 35.7
-21.6

34 4.79 16.62

Reduced sunlight

6 3.20 12.10
72.7

20 5.53 19.99 23,2
-28.7

34 3.94 15.78





RICE FERTILIZATION fUlAtAGVEIT


D. M. Brandon
Professor of Arronomy
Louisiana State University
Rice Experiment Station

Introduction

An adequate and balanced nutritional level is essential in the rice plant
through the entire growing season for maximum grain yield. Productivity and
profitability of rice depends on several factors but fertilization management is
one of the more important factors. flineral nutrients are only a minute part of
total plant dry matter but a deficiency of any one of the 16 essential nutrients
can severely limit growth, development, and grain yield of rice. Suboptimum or
excessive amounts of plant nutrients cause poor rice performance and limit net
profits.
The most frequently limiting plant nutrients in Louisiana rice in order of
importance are nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn).
Frequency and severity of plant nutrient deficiencies depend primarily on soil
type as it relates to native fertility, crop and fertilization history, rice
variety, and fertilization management as it relates to source, time, and method
of plant nutrient application. Nitrogen fertilization is emphasized here because
it is most frequently needed for maximum yields and severe to moderate deficiencies
are often observed in rice.
Phosphorus, Potassium, and Zinc Fertilization
Soil tests should be used to determine P, K, and Zn requirements for rice
in a-given soil. Phosphorus fertilizer should be applied when the soil P concen-
tration of 0.1 NHCl extractable-P is 12 parts per million or less. Potassium
fertilizer should be applied when the 0.1 NHC1 extractable-K is 60 parts per
million or less. Zinc fertilizer is usually required when the soil pH is greater
than 7.0 and DTPA extractable-Zn less than 0.7 parts per million. Zinc deficiency
is most frequently observed in areas that were heavily "cut" during leveling.
Timing of P, K, and Zn fertilization is critical for maximum rice yields.
These plant nutrients should be soil incorporated 1 to f inches before or at
planting in the drill-seeded system. Delay of these nutrients in deficient soils
often results in slow seedling growth, delay of permanent flood in drill-seeded
system, and reduced grain yield. Plant P, K, and Zn deficiency symptoms show i:,
rice about 18 to 25 days after seeding and their effect on rain yield increases
with time. Applications of these nutrients prior to planting assures an adequate
amount of them through the growing season and prevents early deficiencies that
reduce seedling vigor, stand establishment, tillering, and grain yield. Soil
incorporation of P, K, and Zn is desirable because it places the nutrients in the
root zone and reduces their effect on weed growth. Post-plant applications of
P, K, and Zn may be beneficial if applied soon after deficiency symptoms shot
but the longer their application is delayed, the lesser will be the plant and
yield response.
Phosphorus and K deficiencies can be corrected in rice by applications of
40 to 60 pounds P205 and K20 per acre. Higher rates of these plant nutrients
generally are not required for maximum yield. Zinc deficiency in rice can be
corrected by application of 1.0 to 8 pounds Zn per acre as zinc sulfate, zinc




(10)


oxide, or one of the zinc chelates. The specific amount of Zn required depends
on severity of the deficiency and time and source of Zn application.
Nitrogen Fertilization

Nitrogen is the most frequently limiting plant nutrient in rice. Management
of U has a profound effect on rice productivity and fertilization practices that
maximize 11 efficiency usually maximize grain yield. The amount and time of N
fertilizer application are critical for optimum performance of rice. Suboptimum
or excessive rates of N often limit yield potential and increase production
costs. Nitrogen is required within the first 20 to 30 days after seeding to
prevent plant deficiency which results in slow growth, poor seedling vigor,
reduced tillering, and potential grain yield. An efficient N fertilization
program will provide a sufficient amount of N at the proper time to prevent 1I
deficiency during the critical yield determining growth stages of tillering and
panicle formation. The amount of total N required for maximum yield depends on
native soil F fertility, rice variety, source, time, and method of N application,
and other factors.

Nitrogen Timing in Relation to Plant Growth and Permanent Flood
The time of H fertilizer application in relation to plant growth and
permanently flooding drill-seeded rice greatly influences performance and M
utilization efficiency of all rice varieties. A continuously available source
of N must be maintained in the soil-plant system through the entire vegetative
and reproductive stages for maximum grain yield. Rice seedlings began to show
N deficiency symptoms 18 to 22 days after drill-seeding in N deficient soils.
Persistence of the deficiency greatly reduces seedling growth, stand density,
tillering, and grain yields. When severe N deficiency occurs early in rice,
lost yield potential usually cannot be recovered by even excessively high N
topdress applications, especially in very early maturing varieties such as
Labelle.

A continuous supply of N can be maintained in drill-seeded rice by appli-
cation of 20 to 30 pounds N per acre before or at planting followed by applica-
tion of most of the total N requirement just before permanently flooding the
crop. Grain yields of drill-seeded Saturn rice were maximized by application
of all or most of the M preplant when near optimum total rates of 80 to 100
pounds N per acre were applied in a Crowley silt loam soil (Fig. 1). Split N
applications which consisted of low preplant rates followed by high topdressed
rates resulted in lower grain yields because of early N deficiency that limited
yield potential. Split application of suboptimum total N rates often result
in less efficient N utilization than when all or most of the N is applied pre-
flood (Fig. 2). Conversely, split application of excessive N rates, such as
160 pounds N, per acre (Fig. 2), may result in greater yields than a single pre-
plant application of an equal N rate. Excessive M rates should be avoided,
however, because they reduce grain yield, quality, and net profits. The
influence of N timing in relation to permanently flooding drill-seeded Labelle
rice is shown in Table 1. This data exemplifies 5 years of research that shows
N efficiency can be maximized in drill-seeded rice by surface applications of
most of the total N just before permanently flooding the crop. Nitrogen
deficiency existed in all timing treatments, except the at planting treatment,
at the time of N application although the rice was flooded 25 days after plant-
ing. Consequently, yield reduction in the postflood N applications was caused
partially by delayed N application and N losses from the soil-water system.







80


70


60-


ALL PREPLANT D SPLIT


L.S.D. 0.05


501


40


30F


20
PREPLANT
TOPDRESS
TOTAL N


p


A


m


li
I


0 20 2040 20 40 60 20 40 60 80 40 60 80 100 60 80 100 80 100 100
0 0 20 0 40 20 0 60 40 20 0 60 40 20 0 60 40 20 60 40 60


0 20


40


60


100


120


140 160


N RATE, lb/acre


FIG. 1. EFFECT OF PREPLANT AND SPLIT N APPLICATIONS ON GRAIN YIELD OF
EXPERIMENT STATION.


SATURN RICE LSU RICE







TIME OF N


1 100% PREPLANT
2 65% PREPLANT.+ 35% @ PANICLE INITIATION
3 65% PREPLANT + 35% 8 PANICLE DIFFERENTIATION


LSD.05





x
- r
!
z
m


w
z
0
:E w
w m3
U D
WI -
m
Cd


60

-Q
w

650
0




-J
w

Z
t40



ID30


F-
z
z
0
I m
w
-J
m_ __

irmvFt-


312


312


N(
cu

z
O
d;


211


w
LU
I-
z
o w
2
w r
Jw
-J m
w


I-
z
0

---


<>
O
0
x z



C I I

I
-i n


Bu 160
N RATE, Ib/acre
FIG. 2. EFFECT OF N RATE AND TIME OF APPLICATION ON GRAIN YIELDS OF EARLY AND
MIDSEASON LONG-GRAIN RICE VARIETIES.


70-


312




(11)

These data clearly show that maintenance of continuously available N in the
soil-plant system is essential for optimum rice performance. Moreover, N
fertilizer efficiency can be maximized in the drill-seeded system by applying
most of the N preflood rather than postflood in water.
Sources and Rates of Nitrogen
Rice will equally utilize ammonium (Nil4) and nitrate (rc03) forms of N
but only iH4-N can be efficiently maintained in a flooded soil system.
Nitrate-N is not recommended for rice because it is subject to denitrification
loss, and excessively high NO3 rates may be required to meet the plant N require-
ments. Conversely, NH4-rl placed 0.5 to 3 inches deep into a soil which is
flooded soon after N application will remain in the soil if the soil is continu-
ously flooded. Ammonium sulfate and urea are the most common dry sources of N
in the South. Aqua-NH3 is a common liquid N source in California. Ammonium
sulfate and urea are dissolved in water and move downward into the soil to the
depth of water penetration when applied to dry soil and flooded soon thereafter.
These sources remain on the soil surface and are subject to loss, however, when
applied to a saturated or flooded soil. All dry N sources should be lightly
soil incorporated when applied preplant. The irrigation flood water will move
surface applied N down into the soil with the wetting front if the soil is dry
and flooded soon after N application.

Varietal Response to Nitrogen and Relative Nitrogen Rates
Rice varieties often differ in responsiveness to N because of differences
in agronomic characteristics such as seedling vigor, maturity, straw strength,
disease reaction, and plant height. Physiological characteristics, such as N
uptake and utilization efficiency which reflect inherent efficiency of metabolic
processes, also may differ among varieties. A general recommendation relative
to total rate of N required for optimum grain yield of a given variety is often
of limited value because the rate required will depend on total management of
the crop, timing and method of N application,' timing of permanent flood, native
soil fertility, etc. Nevertheless, efforts are made continuously to quantify
the N requirements of major southern rice varieties through field and laboratory
research. General N recommendations are at best a guideline designed to assist
producers in maximizing varietal performance.

Semidwarf and lodging resistant rice varieties usually require slightly
higher N rates than tall and weak straw varieties for maximum grain yield.
The semidwarf long-grain Leah (LA026) generally requires about 10 to 30 percent
more N than tall Lebonnet and Labelle (Fig. 3). Grain yield of Lebonnet and
Labelle increased to a maximum of approximately 5800 pounds per acre with
increasingly higher N increments of 0 to 100 pounds N per acre but additional
N increments resulted in yield reduction because of lodging (Fig. 3). Grain
yield of Leah increased to approximately 6500 pounds per acre with increasingly
higher N increments of 0 to 130 pounds N per acre but unlike Lebonnet grain
yields did not decrease greatly with excessive N because of the inherent lodging
resistance of Leah (Fig. 3).
Typical N response patterns of medium-grain rice varieties are shown in
Fig. 4. Saturn and Brazos are tall lodging susceptible varieties that require
relatively low N for maximum yield. Conversely, Mars is a relatively short,
stiff straw variety that has higher yield potential than Saturn and requires
more N for maximum yield (Fig. 4). Mars is rapidly replacing Saturn in
Louisiana because of its lodging resistance and higher yield.





















L-201


LEBONNET, R2.


O
X

o 40 /LABELLE, R =.90


w
: 30- BELLEMONT,R2 =.91
1--

O

._ 20 NEWREX,R =.87*


S10


z


0 40 80 120 160
N RATE, Ib/acre

FIG.- 3. GRAIN YIELD RESPONSE OF EARLY TO MIDSEASON LONG-
GRAIN VARIETIES TO PREPLANT N FERTILIZER LSU
RICE EXPERIMENT STATION.


















80


o

BRAZOS,R =.38
70-




| 60- // /SATURN,R =.56**
0
-o
C\l

5 50- M 7, R =.59


z

.-(D 40
0 40 80 120 160

N RATE, Ib/acre

FIG. 4. GRAIN YIELD RESPONSE OF MEDIUM-GRAIN RICE VARIETIES
TO PREPLANT N FERTILIZER LSU RICE EXPERIMENT
STATION.










TABLE 1. EFFECT OF TIIE OF i! APPLICATION ON PERFORMANCE OF DRILL-SEEDED LABELLE RICE/

GRAIN YIELD @ 12% MOISTURE
N RATE TIlE
TI OF N APPLICATION 50 100 150 MEAN
---------------------Ib/acre---------------------

i DAY PREFLOOD 3280 4460 4760 4170A
A PLAilTIiG 3150 4010 5220 4130A
10 DAYS FREFLOOD 2960 4140 5050 4050A
DAY CF FLOOD 3000 3800 4700 3830B
3 DAYS PREFLOOD 2980 3790 4720 3830B
8 DAYS PREFLOOD 2740 3770 4430 3650C
PREFLCOD iEAN 3020 4000 4810 3940
3 DAYS PCSTFLOOD 2200 2070 2340 22000
1 DAY POSTFLOOD 2090 2230 1970 20900
PQSTFLOOD ilEAN 2150 2150 2160 2150
M! RATE iE AN 2800A 3530B 4150C
LSD .05 570
C.V., % 6.1
I/ LSU RICE EXP. ST!I., CROILEY SILT LOAM SOIL, 1980.




(13)


Summary
A continuous supply of plant nutrients in amounts adequate for optimum
rice growth, development, and grain yields is necessary for efficient rice
production. The most frequently limiting plant nutrients in rice are N, P,
K, and Zn. The need for P, K, and Zn fertilizers in a given rice field should
be determined by soil tests, nitrogen fertilizer is usually required for
maximum rice yield. Plant deficiency symptoms of these plant nutrients
usually are visible in deficient soils 18 to 22 days after seeding. Persis-
tence of N, P, K, or Zn deficiencies greatly reduce seedling vigor, plant
density, tillering, and grain yield.

Timing of N fertilizer in relation to plant growth and permanently flood-
ing rice greatly influence performance of all rice varieties. A continuous
supply of N should be maintained in rice by application of 20 to 30 pounds N
per acre preplant followed by soil surface application of most of the total N
requirement just before permanently flooding drill-seeded rice. Nitrogen
applied at planting will prevent N deficiency during the planting to permanent
flood interval. Nitrogen applied just before flooding will move into the soil
with the water on flooding and be retained in the soil for plant uptake if a
flood is maintained. Delaying all N fertilizer until after flooding results
in severe N losses and inefficiency.

Rice varieties differ in responsiveness to N. Semidwarf varieties and
tall lodging-resistant varieties usually require 10 to 30 percent more N than
tall lodging susceptible varieties for maximum yield. The semidwarf variety
Leah performs equally to tall Lebonnet at low to near optimum N rates, however,
Leah produces much more rice than Lebonnet when fertilized with near optimum
to excessive N rates. Lebonnet grain yields increase to a maximum with increas-
ing N but decrease greatly with excessive N'because of lodging. Conversely,
Leah grain yields increase to a maximum and remain relatively stable with
excessive N because of no lodging. Excessive N should be avoided, however,
because it decreases yield, grain quality, and profitability of rice.




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HERBICIDES FOR WEED CONTROL IN RICE
J. A. Dusky

Introduction

Rice weed control research conducted during 1981 focused on determin-

ing combination treatments for early postemergence weed control and
providing residual activity until the time of flooding. Experiments were
also conducted to determine the effect of propanil (Stam) application at
the 2 leaf, 4 leaf and 6 leaf stage of rice on yield results. Each of

these experiments will be dealt with individually in this report.

Effects of Propanil Applications at Various
Stages of Growth on Rice Yield

Rice was seeded at a rate of 80 Ibs per acre at the research station

in' aone quarter acre plot. The plots were 12ft x 30 ft in a randomized
complete block design with two replications. Plots were sprayed with
propanil (Stam) at rates of 1.5 and 3.0 lb ai/A when the rice seedlings
reached the 2-leaf, 4 leaf and 6 leaf stage of growth irregardless of the
weed stage of growth.
Results for weed control efficacy four weeks after treatment are

given in Table 1. Few weeds were present when the rice was in the two
leaf stage. Consequently, weed control four weeks after treatment with
both rates of propanil were only 45-50%. At the 4 leaf stage of rice
growth, weeds were in the 2-4 leaf stage and efficacy of the treatments

was increased up to 85% with 3.0 lb ai/A of propanil. Weeds were at the
4-8 leaf stage of growth when the rice was at the 6-leaf stage and weed
control was not different from that obtained at the 4-leaf stage of
rice growth. The predominant weed species were Amaranthus spinosa

(spiny amaranth), Commelina sp. (dayflower) and Echinochloa crusqalli
(barnyard grass).




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Damage to rice from propanil treatment increased as the rice
advanced in its stage of growth, that is, the smaller the rice the less
damage from propanil treatment. This is reflected in yield results

(Table 2). Also, the higher the rate of propanil the more severe the

damage. This is also reflected in the yield results.
From this study it appears that less rice damage is experienced
when rice is treated with propanil at the 2-leaf stage. It may be
necessary to time planting of rice just before a flush of weeds might

be expected, then weeds are controlled with little damage to the rice.
The addition of a compound to the propanil treatment that would provide
residual herbicide activity might be advantageous.

Herbicide Trials 1981

Trials were conducted during the spring of 1981 to evaluate ef-
ficacy of weed control of treatments with propanil, NC20484, Bolero,
Machete, Modown, Blazer and Basagran; alone at various rates and in
combination with propanil at four locations. At two locations the

variety Lebonnet was planted and at the other two, one had Mars as
the variety the other Newrex. Experimental design was a randomized
complete with three replications, each plot being 600 square feet.
Results four weeks after treatment for weed control and vigor are

given in Table 3. These results are the averages of three of the four

trials. The trial with the variety Mars was not included in the table
because Mlars was more tolerant to treatment with propanil. The weed
control ratings were basically the same as the other trials. Major

weed species present were Eleusine indica goosegrasss), Panicum

adspersum (broadleaf panicum), and Amaranthus spinosa (spiny amaranth).
The only compound that was severely phytotoxic was Blazer. The
other treatments resulted in little or no phytotoxicity. However, it

is interesting to note that combination treatments with propanil at




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3.0 lb ai/A always resulted in more phytotoxicity, i.e., less vigor.
NC20484 provided acceptable weed control only when it was used in

combination with propanil. Bolero provided more than 80% control of
grass weed species and broadleaf weed control was enhanced with the
addition of propanil. Machete at the lowest rate (4.0 lb ai/A) pro-
vided less than adequate weed control. However, at the 8.0 lb ai/A

rate weed control was increased. Again, weed control was increased
with the addition of propanil. Modown, even with the addition of
propanil, provided only 80% control of broadleaf weeds and 70% grass
control. Blazer at 1.0 lb ai/A provided excellent control but was
severely phytotoxic. Basagran at the highest rate (1.5 lb ai/A) pro-

vided adequate control but weed control was enhanced with the addition
of propanil.
In general, the results indicated that all the compounds provided
acceptable weed control when propanil was added to the treatment with
little or no phytotoxicity (except Blazer). However, the addition of
propanil also increased phytotoxicity to the rice. Studies are being
continued to evaluate these compounds.




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Table 1. Ieed control ratings four ijeeks after treatment with
Propanil at various stages of rice growth.

Stage of growth Rate (Ib ai/A) Ueed control
2 leaf 1.5 50
3.0 45

4 leaf 1.5 60

3.0 85

5 leaf 1.5 63
3.0


Table 2. Effects of Propanil at
on rice yields.


various rice stages of growth


Stage of Growth

2 leaf


4 leaf


G leaf


Rate (lb ai/A)
1.5
3.0

1.5

3.0

1.5
3.0


Yield (Ibs/A)

6418a
4284bc

463C.b

3462c

4772b

44G2bc




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Table 3. Heed control and vigor ratings four weeks
three trials.


after treatment. Average of


Treatment

Check

Propanil

Propanil

[IC20484

HC20484

NC20484

NC20484 + Propanil

NC20484 + Propanil

Bolero

Bolero + Propanil

Bolero + Propanil

Bolero + Propanil

Hachete

Machete

Machete + Propanil

Hiachete + Propanil

Ilodown

Hodown

Modown + Propanil

Blazer

Blazer

Blazer + Propanil


Time of
Rate (lb ai/A) Application*


1.5 EP

3.0 EP

0.5 PRE

1.0 PRE

2.0 PRE

0.5 + 1.5 PRE + EP

0.5 + 3.0 PRE + EP

4.0 EP

4.0 + 1.5 EP

3.0 + 3.0 EP

3.0 + 2.0 EP

4.0 EP

8.0 EP

4.0 + 3.0 EP

4.0 + 1.5 EP

2.0 EP

3.0 EP

3.0 + 3.0 EP

0.5 EP

1.0 EP

0.5 + 3.0 EP


ifeed Control**


Heed Control**
Broadleaf Grass

0.0 0.0

G.5 5.2

8.7 7.5

4.2 5.3

5.3 4.8

7.6 5.4

8.2 6.7

8.9 7.1

6.4 3.2

7.3 9.0

9.5 9.0

9.4 9.2

4.3 5.2

C.7 7.2

8.2 0.0

8.3 3.4

6.7 4.3

7.2 5.2

8.3 7.1

G.7 7.0

9.2 8.5

9.C 9.5


Vigor***
10.0

9.6

8.3

10.0

9.8

9.8

9.2

8.0

9.8

9.2

9.5

9.8

9.5

9.6

9.2

9.8

9.0

9.8

9.1

4.5

3.0

2.5




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Table 3. (Continued)

Time of Heod Control**
Treatment Rate (lb ai/A) Application* Droadleaf crass Vigor***

Basagran 0.75 EP 7.5 4.2 9.8

Basagran 1.5 EP 8.2 7.3 9.5
Dasagran + Propanil 0.75 + 1.5 EP 9.6 9.0 C.9

* EP = Early Postemergence; PRE = Preemergence

** 0.0 = No weed control; 10 = 100% weed control

*** 0.0 = no vigor; 10 = no damage




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EFFECT OF RICE HUTRITIOJ0 Oil DISEASE DEVELOPiEIIT

J.P. Jones, J.P. Crill, E. Andrade U., F.L. Huque, and B.A. Estrado
Solution culture techniques were used to determine the effect of nitrogen

source and rate and silicon, potassium, calcium, and magnesium rates on the
development of blast, brown spot, sheath blight, leaf scald, and bacterial leaf
blight of rice.
Blast severity was greatly increased by nitrate-nitrogen (I103-1I) compared

to ammonia-nitrogen (W!I4-l1) and by an increased nitrogen rate. Increasing
potassium rates increased, then decreased blast severity in a nonlinear manner.
Silicon added to Il--H'! solutions, silicon slightly decreased blast.
The incidence of brown spot was increased by an increase in nitrogen rate

and by H03-11 compared to iH4-1f in the absence of silicon. Disease severity

was decreased by silicon amendments; potassium results were inconclusive.
The percent tillers with sheath blight increased with an increased nitro-
gen rate. The disease was not influenced by nitrogen source, potassium rate,
or silicon rate.

Leaf scald was favored by 200 C temperatures compared to 250 C or 30 C.
Lesion length was increased by increasing nitrogen or calcium rates. A very
high rate of potassium (120 ppm) increased disease severity on a susceptible
but not on a tolerant variety.

Nitrogen rate greatly affected elongation of bacterial leaf blight lesions
and the incidence of kresek. Silicon and i103-f! (as compared to I!l14-[l) en-
couraged lesion elongation, but not the occurrence of kresek. Increasing
potassium rates increase lesion length.




The senior author, J.P. Jones, is a professor of plant pathology at AREC-
Bradenton.




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APPENDIX A

Rice, Water, and the Everglades

For thousands of years it has been known that rice is well adapted to a semi-
aquatic habitat, and that rice production is enhanced by flooding the soil to a depth
of 4 to 6 inches during a portion of the growth cycle. The reason for this enhance-
ment has been pondered by many scientists but has not been fully resolved. Some have

suggested that flooding is needed mainly for weed control, or to maintain plant avail-
able levels of iron or phosphorus, or to support nitrogen fixing algae. Apparently,
the flood culture is not needed solely to supply unusually large amounts of water to
the plant. Over 35 years ago the plant physiologist Lin pointed out that "there is
no evidence that throughout its growing period the rice plant has a water requirement

especially higher than that of dryland plants"1. This conclusion is born out by data
collected in Florida on the combined evaporation from the soil surface and the eva-
poration from the leaf surfaces (transpiration), a combination called evapotranspir-
ation (Table 1).

Rice evapotranspiration is greatest for a 5 to 6-week period beginning with the
initiation of the reproductive phase and concluding several weeks before the grain
is ready to harvest. At other times it is relatively low. Compared to perennial crops
such as citrus, pasture and sugarcane which have much more biomass in the field
throughout the year, rice, being an annual, requires relatively little water during
many months. Only about 120 days elapse from seeding to harvest, and a second
"ratoon" crop can be obtained in another 70 days. Fortunately, its period of highest
water requirement usually coincides with the summer rainy season in Florida. Thus,
except for very early planted rice, the water requirement falls below normal monthly

precipitation. Furthermore, rice evapotranspiration almost always is below that of
the native sawgrass that once covered the Everglades, and still predominates in some
water storage areas.


Lin, C.K. 1946. Effect of oxygen and sodium thioglycollate on growth of rice.
Plant Physiology 21: 304-318.




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In addition to the obvious benefits accruing from rice production, such as

increased summer employment, a local food supply, and a general enhancement of south
FloridA's economy, there are some important environmental benefits as well. The
richest, most productive soils in the State, the organic soils of the Everglades
Agricultural Area, were formed under a flooded condition and are being lost by the
biological oxidation that accompanies drainage. The flood culture used for rice stops

this loss of soil. It also stops the formation of nitrate-nitrogen that results from

the oxidation, which reduces the problem of nitrate enrichment of surface and ground
waters. Flooding is a biological means of controlling nematodes and soil born
insects, which reduces the need for pesticides on crops following rice. Since rice

must be grown in the summer, a time when excess water is the usual problem and areas

for water storage are needed to prevent freshwater releases into the ocean, rice
production increases south Florida's water storage capability and reduces the immed-
iate need to transport and store water following rainfall events. Finally, rice,

more than any other crop, brings back the "river of grass" landscape for which the
Everglades once was known.




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Table 1. Evapotranspiration of citrus, pasture (or home lawn), sugarcane, sawgrass,
and rice in Florida, normal rainfall and evaporation from an open water
surface (pan evaporation) in the Everglades Agricultural Area.

Pasture2
S or home 3 4 56 Pan
Month Citrus lawn Sugarcane Sawgrass Rice Rainfall evaporation
- ------- -- (inches) -
Jan. 2.09 2.01 1.42 5.61 1.97 3.39
Feb. 2.60 2.52 1.10 4.93 1.97 4.00
March 3.58 3.35 2.52 6.24 3.21 5.70
April 4.49 4.21 3.39 7.53 1.63 2.96 6.54
May 5.31 5.20 4.80 9.64 3.07 4.47 7.06
June 4.41 4.25 5.98 7.05 5.82 9.08 6.24
July 4.88 4.80 6.50 9.95 8.43 8.58 6.36
August 4.80 4.80 6.69 8.80 3.05+(2.00) 8.21 6.12
Sept. 4.02 3.86 5.12 8.93 (5.00) 8.82 5.31
Oct. 3.59 3.43 5.20 7.60 (3.00) 5.65 4.82
Nov. 2.72 2.48 3.19 4.14 1.74 3.71
Dec. 2.09 1.93 2.59 3.62 1.80 3.19


Total 44.58


42.84


48.50


84.04


22.00
(10.00)


58.75


62.44


IData from water balance in S.W.A.P., Ft. Pierce (unpublished).

2Stewart, E. H. and W. C. Mills. 1967. Effect of depth to water table and plant
density on evapotranspiration rate in southern Florida. Trans. ASAE 10: 746-747.
Mean monthly values averaged over 5 years (3 years Tifway bermudagrass and 2 years
St. Augustine grass) and over water table depths of 12, 24 and 36 inches maintained
in lysimeters at Ft. Lauderdale, FL. These turfgrass evapotranspiration values
are assumed to be valid for pastures adequately supplied with water.


3Shih, S. F.
Trans. ASAE
36 inches.


and G. J. Gascho. 1980. Water requirement for sugarcane production.
23: 934-937. Data averaged over the water table depths of 12, 24 and


From Table 13, Clayton, B.S., J. R. Neller and R. V. Allison. 1942. Water control
in the peat and muck soils of the Florida Everglades. University of Florida
Agricultural Experiment Station Bulletin 378. The data are for one year only. The
sawgrass was not flooded but a 1-foot water table was maintained.

5Shih, S. F. 1981. Rice-Water Relationships. p. III-1 to III-5 in Belle Glade
AREC Research Report EV-1981-3 "Fourth Annual Rice Field Day". Assuming planting
date of April 15th which is approximately the middle of the planting season. Values
in parenthesis are estimates for a ratoon crop. (Rice is not always ratoon cropped).
Months with no values are periods when an April planted crop is not present in the
field.
6Belle Glade weather records, Univ. Florida-AREC, P.O. Drawer A, Belle Glade,
FL 33430