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THE ENF'LUENCE 0F 2', 40 AND MALEIC

HYDRAZEDE ON THE SUCROSE CONTEN?
OF SUGAR CANE

Thesis for #519 Degree of M. S.
MiCHiGAN STATE COLLEGE
Ra§ae§ Gran?
W53

 

0-169

{s ‘ I . .
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This is to certify that the

thesis entitled

The Influence of 2,h-D and Maleic
Hydrazide on the Sucrose Content
of Sugar Cane

presented by

Rafael Grant

has been accepted towards fulfillment
of the requirements for

_MS__degree {n.EQILHJLIEPB

223%

Major professor

Date November 25, 1953

 

 

 

 

 

 

 

 

 

THE INFLUENCE OF 2,hD AND MALEIC HYDRAZIDE ON

THE SUCROSE CONTENT OF SUGAR CANE

by
mm. GRANT

A THESIS

Submitted to the School of Graduate Studies of
Michigan State College of Agriculture and
Applied Science in partial fulfillment
of the requirements for the degree of

MASTER.OF SCIENCE

Department of Farm.Crops
19 53

ACKNOWLEDGMmNTS

The writer wishes to express his sincere thanks and
appreciation to Dr. E. E. Down, under whose inspiration,
supervision, and unfailing interest this work was undertaken.
Grateful acknowledgment is also expressed to Dr. M. A. Lugo,
of the Agricultural Experiment Station of the University of
Puerto Rico, under whose immediate supervision the research
was carried out. Appreciation is rendered to Dr. G. Samuels,
of the Agricultural Experiment Station.of the University of
Puerto Rico, and to Mr. H. M. Brown and Dr. S. T. Dexter, of
the Farm Crops Department, for valuable suggestions and re-
vision of the manuscript. Indebtedness is expressed to
Dr. A. Roque and Dr. B. Capo, of the Agricultural Experiment
Station of the University of Puerto Rico, through whose
authorization of funds and facilities of that Station this
study was made possible. The author is also indebted to the
Eastern Sugar Associates of Caguas, Puerto Rico, for granting
financial help and the use of their sugar cane fields. Here-
with, I also acknowledge the cooperation of Mr. A. Riera and
Mr. I. Igaravidez, of the Agricultural Experiment Station of
the university of Puerto Rico, who performed the laboratory

analyses.

TABLE OF CONTENTS

Page

INTRODUCTION................... 1
REVIEWOFLITERATUHE...............

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MSTHOD OF EKPERIMENTATION . . . . . . . . . . . .
Equipment and Materials
Layout of Plots
Spraying Method
Sampling and Analysis of Juices

DESCRIPTION OF THE EXPERIDEVTS . . . . . . . . . . 9
The Rio Piedras No. l and the Humacao
Experiments
The Rio Piedras No. 2 Experiment
The Gurabo Experiment

AJNALYSIS OF THE: DATA 0 O O O O O O O 0 O O O O O O 12
Example of Analysis of Variance

PerSENTATIONOFTHEDATA............. 11.
Description of Results

DISCUSSIONoeeoeooeeooooeooeeee 23
SUI‘fi'iARYooeeeoeoeeeoeoeoeeoeo 25

HTWTURE CI’IIJE‘;D O O O O O 0 0 O O O O O O O O O O 26

THE INFLUENCE OF 2,4D AND MALEIC HYDRAZIDE ON

THE SUCROSE CONTENT OF SUGAR CANE
INTRODUCTION

The Commonwealth of Puerto Rico is the most eastern
soil of the Greater Antilles. On this island, 2,210,700
people are spread over approximately 3,435 square miles, with
a density of 6&5 to the square mile, one of the greatest re-
corded throughout the world. The main crops of the island
are sugar cane, coffee, and tobacco. About $235,000,000 worth
of commodities are exported every year, mainly to the continenp
tal United States. Of this figure, #2 percent, approximately,
represent sugar exports. The hegemony of sugar is patent and
upon it rests the economy of the Commonwealth. The bulk of the
sugar cane crop is produced on the coastal plains, mostly close
at sea level. Sugar cane (Saccharum.officinarum) was introduced
by the Spanish Conquistadores as early as 1515. During the last
century the crop developed in importance as a local enterprise,
mainly to supply the sugar needs of the island. With the incom-
ing of American capital at the beginning of this century and
with the opening of the United States market, sugar has steadily
grown in importance to become the most decisive factor in the
socioeconomic picture of Puerto Rico.

The agricultural phase of this industry has been the

object of different and varied studies on the part of the
producers and the government. In sugar cane, as well as in
best production, the aim.is a harvest of heavy tonnage with
the highest possible concentration of sucrose. In a large
measure, research studies have been dedicated to the improve-
ment of varieties, of fertilizer practices, and of cultivation
methods. Considerable progress has been made in obtaining
large sugar cane crops; nevertheless, variations in sucrose
content still elude practical control. (Graph No. 1.)

very low percentages of sucrose in this sweet grass
have been reported by the Eastern Sugar Associates in the
eastern part of the island and by the Land Authority of Puerto
Rico in the northern part. In these two areas large sums of
money are expended every year in the hope of improving sucrose
yields by cultural practices.

At various times consideration has been given to the
possibility of modifying the metabolic processes of the sugar
cane plant at a time approaching the harvesting season. There
are starches and reducing sugars in the stalk as well as in the
leaves of the cane. Through this modification in the metabolic
processes it was hoped to convert these reserve materials, or
at least part of them, into sucrose. As a consequence of these
conversions an increase in the final sucrose concentration of

the millable cane was contemplated.

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REVIEW OF LITERATURE

For the past two decades many plant growth regulators
or hormone-like substances have appeared on the market for agri-
cultural use, mainly as weed killers. Among them.2,AD has been
used most widely.

Beauchamp (1)* reported that, in Cuban plantations, in-
creases in sucrose of 1.A to 2.0 percent were obtained from
dusting the cane foliage of varieties P.0.J. 2878 and Media Luna
3/18 with four to six ounces to the acre of the sodium.salt of
2,AD. The increase in sucrose content was more marked during
the first ten days following treatment, than at other dates.
Promising results have been reported from.some other areas (3).

However, Loustalot, gt.§;,, (4) at Mayaguez, obtained
no increases in the sucrose content of variety M 336 by sprayh
ing the foliage with a 0.2 percent isopropyl ester of 2,AD.

In their report the control plots produced about the same su-
crose percentage yield at harvest time as the treated plots.

There have been reports that indicate that 2,AD.appli-
cations may affect the sugar metabolism.of other plants. wort
(l3), from.British Columbia, reported increases in the total
sugar content of the stem of buckwheat after treatment with

small non-lethal doses of the ammonium salt of 2,hD, (50, 100,

 

*Numbers in parenthesis denote literature cited.

A

and 1000 parts per million), within one day after application.
Total sugars in the stem.and leaves rose considerably within
one day after application, but fell again by the second day.
Maleic hydrazide, one of the latest hormone-like sub-
stances to be described, has been found to have striking effects
on plant growth, development, and flowering (7). Naylor and
Davis (6) observed that corn plants sprayed with maleic hydra-
zide exuded droplets of sucrose and accumulated anthocyanin
pigments. Quantitative sugar analyses indicated a thirteen-
fold increase in sugar concentration. Ririe and Mikkelson (10)
obtained evidence that maleic hydrazide influenced sugar beet
growth and increased the sugar content. Foliar sprays contain-
ing 0.3 and 0.025 percent, made at the rate of 50 gallons per
acre, were applied; and sucrose content was determined at three
dates of harvest. An exudate appearing on barley after appli-
cations of maleic hydrazide was analyzed for sucrose by Currierr,
g§_§l. (2). Sucrose and starch were increased in cotton follow-
ing applications of maleic hydrazide (5). However, Stout (11)
and Peto, §§_§l., (9) reported no significant increases in the
sucrose content of sugar beets when treated with maleic hydrazide.
Wittwer and Hansen (12) reported that sprays with 0.25 percent
maleic hydrazide 30 to 40 days prior to harvest, or even as late
as 3 or 5 days before harvest, considerably decreased the storage

losses of sucrose in sugar beets.

THE RESEARCH PROBLEM

In view of the contradictory reports concerning
the role of 2,4D on sugar yields and because of the interest
shown by the sugar concerns in its use, work was undertaken
to reinvestigate the role of 2,AD on this particular issue
in controversy. Furthermore, specific attempts were made
to determine the influence of MH30 (maleic hydrazide) as a
possible inducer of changes in the sucrose content of the

cane o

METHOD OF EXPERIMENTATION

“ ' nt and Materials. Standing sugar cane which had

been harvested a number of years was sprayed with two hormone—
like substances: (1) 2,AD, 97 percent sodium.salt, (monohydrate
dichlorophenoxiacetic acid), equivalent to 82 percent of the acid,
commercial type; and (2) MHBO, maleic hydrazide, (1,2—dihydro-
pyridazine-3,6-dione), formulated as a water soluble diethalona-
mine salt, containing 30 percent of the active ingredient by
weight as used. "Draft" at a rate of 0.05 percent was used as a

wetting agent.

Layout of the_plots. The fields selected in each experi-
ment were divided into six blocks of ten nearly square plots each,
thus providing for a randomized block layout, with 10 treatments,
replicated six times. Each plot had an area of approximately 0.01
acre. A row of cans was cut around each plot and two rows‘were'
left standing between every two plots to serve as buffer strips.
Between each two plots there was a 20-foot separation. The row
of cane that was cut around each plot provided a convenient path-

way to facilitate spraying operations.

Sprayinggmethgg. Spraying operations with a knapsack
sprayer, 8001 nozzle, were started before 6 A.M; in each case,
to avoid drafts. The required amount of chemical was dissolved

in a gallon of water for each plot, which was enough to wet the

foliage thoroughly. With an extension attached to the hose,
and with the nozzle tied to a bamboo pole about 12 feet long,
it was possible to raise the nozzle sufficiently to spray the

leaves thoroughly from.the top.

Sggpling and analysis of the juices. At harvest time
convenient sugar cane scales were used in the field to obtain
the weight data. Sampling was done for every plot and the mill-
ing of the cane samples was done at the experimental hydraulic
mill of the Station. Juices were sampled and were analyzed by
using a saccharimeter for total solids and polarization readings
were taken with a polariscope. From that data, purity and avail-
able 96 degrees sugar percent canel were calculated, this latter

with the use of special conversion formulas and tablesz.

 

1Polarizing 96 degrees, centrifugal sugar assumed that a

factory should be able to obtain from canes of a given analysis.

2Capo, B. G., Table of 96° Available Sugar Yields Per Cent
Juice. University of Puerto Rico, Agricultural Experiment Station,
Rio Piedras, Puerto Rico, October, 1943, #8 numb. leaves.

DESCRIPTION OF THE EXPERIMENTS

The Rio Piedras Nogélfand the Humacao Experiments. 1950.

Two fields were selected, one at the Solis Farm.of the
Agricultural Experimental Station at Rio Piedras and one at
Colonia Mandry of the Eastern Sugar Associates, near Central
Pasto Viejo, Humacao. Both fields had been planted to P.0.J.
2878 and about 1A ratoon crops had been harvested. At Rio
Piedras the soil had been classified as Vega Alta clay loam, a
rather extensive, level sugar cane soil of the north coastal
region. At Humacao the soil was originally a muck at a very
low level which had been reclaimed from the sea and had under-
gone considerable mineralization.

The treatments were as follows: Check, 10, 20, and 30
pounds of 2,4D, acid basis, to the acre. The first set of plots
was treated 30 days before harvesting; the second set 20 days
prior to harvest; and the third set 10 days prior to harvest.
Proper check plots were established at random.within every set
of plots.

Ten days after the treatment of the last set of plots all
the cane from.all sets of plots was harvested and weighed in the
field. Random.samples of 25 canes were obtained from.every plot

and were taken to the Station mill at Rio Piedras for analysis.

10

The Rio Piedras Expegiment No. 2. 195;.

Another field was selected at the Station Farm. It
had been planted to P.0.J. 2878 and several ratoon crops had
been harvested. At this location again the soil was classi-
fied as a vega Baja clay, an extensive, level, alluvial sugar
cane soil of the north coastal region of Puerto Rico.

The treatments were as follows: 0, 2.5, 5.0, 7.5,

10.0, and 12.5 pounds to the acre, of 2,4D, acid basis. All
plots were treated at one time.

Samples of ten canes were taken at random beginning the
next day after the application of the 2,AD, and thereafter every
day for 15 consecutive days, commencing on April 15, 1951. Later,
samples were taken every five to seven days until all the cane
was harvested at the end of 46 days.

Analyses of the samples were made the same day they were

brought to the Station.laboratory.

The Gurabo EgperimentI 1252.
The field was selected at Colonia Rio Grande of the

Eastern Sugar Associates, near Central Santa Juana between
Cuguas and Gurabo. The field had been planted to P.0.J. 2878
and several ratoon crops had been harvested. The soil was
classified as a Mabi clay occurring on long gentle slope of
nearly level areas throughout the humid sections, in associa-
tion with the Juncos and Mucara soils derived from tuffaceous

materials.

The treatments were as follows: Control, A ounces, 8
ounces, one pound, and two pounds of 2,4D, acid basis, to the
acre; A ounces, 8 ounces, one pound, five pounds, and twenty
pounds of maleic hydrazide to the acre. The treatments were
administered at one time.

Samples of ten canes were taken at random from.cvery
plot for four consecutive days after establishing the treat-
ment differentials on Feb. 26, 1952. Thereafter, samples were
taken at intervals of three to eleven days. The sampling inter-
vals were more extended toward the end of the experiment. The
last sampling was made on May 9, 1952, some 72 days after the
treatments were given.

Samples were analyzed on the same day as they came into

the Station laboratory.

ANALYSIS OF THE DATA

Statistical analysis was performed for all the four
experiments which included a total of 216 plots. The analysis
of variance was applied according to the following breakdown
of variables in each experiment:

In the Rio Piedras.Experiment No. l and in the Humacao
Experiment analysis was worked out for such factors as tonnage,
polarization, Brix, available 960 sugar percent cane yields,
and purity on the 120 plots of approximately 0.01 acre each.

In the Rio Piedras Experiment No. 2 analysis was
worked out for daily available 960 sugar percent cane yields
for every one of the first 19 days of sampling, as given in
Table No. A, for 36 plots of approximately 0.01 acre each.

In the Gurabo Experiment analysis was applied to the
available 960 sugar percent cane yields for every one of the
12 days of sampling, as given in Table No. 5, for 60 plots of

approximately 0.01 acre each.

Exgmplg of Analysis of Variance.

An example of the analysis of variance of 60 plots of
approximately 0.01 acre each is given in Table No. l as applied
to yields in tonnage, available 96° sugar percent cane yields,

Brix, purity, and polarization.

12

13

Table 1. Sample analysis of variance. Available 960 sugar
percent cane yields in 60 plots of approximately
0.01 acre each. Rio Piedras Exp. No. l, 1950.

 

 

Source D F S S var. f
Total 59 19.80

Treatments 9 1.51 .16 .53
BlOCkS 5 ll- . 70 094 3 013
Error A5 13.59 .30

 

L.S.D. at 5 % - 2.80 for treatments

L.S.D. at 5 % - h.hh for blocks

PRESENTATION OF THE DATA

Descgiption of Results.

A resume of the experimental data obtained in the Rio
Piedras Experiment No. 1, 1950, and in the Humacao Experiment,
1950, are given in Tables numbers 2 and 3, respectively. Mean
values and range of values for Brix, polarization, purity,
available 960 sugar percent cane yields, and tonnage for the
ten treatments are presented. The minimum.difference required
for significance at the 5% level are also stated.

At both localities the results of the experiments
followed about the same pattern.

In continuing the two previous experiments, the Rio
Piedras Experiment No. 2, 1951, is described in terms of daily
fluctuations in available 96° sugar percent cane yields of the
P.0.J. 2878 cane, for six.treatments, as is shown in Table No.

4. Deviations from.the mean of the treatments are presented.

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The Gurabo experiment constituted a refinement in dosages
of those applied in the previous experiments in relation to
2,4D and in addition it included maleic hydrazide treatments.
Table No. 5 shows the yields of available 96 degrees sugar
percent cane yields at various intervals for P.0.J. 2878 treat-
ed with 2,AD and maleic hydrazide. Also the least significant
difference needed for comparison at the 5 percent and 1 percent
levels are given at the foot of the table and in relative corre—
spondence to the means of treatments for each day of sampling.
The mean results of the combined maleic hydrazide and 2,AD
treatments, as well as of controls, are shown graphically in

Graph No. 2.

Sucrose (percent)

20

GRAPH N0. 2.- The daily variations of the
sucrose content of sugarcane receiving
preharvest foliage sprays of ;,4D and
maleic gydrazide as compared to that of
cane from control plots.

 

 

 

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Table 5. The sugar percent cane yields of P.0.J. 2878 at various
cutting intervals as influenced by applications of 2,A-D
and maleic hydrazide. (Colonia Rio Grande, Gurabo, 1952)
==='-[ : : Sugar percent cane yields at various
Number: Treatment : dates of cutting
= Lbs. Hormone 3 2/27 8 2/28 : 2/29 : 3/1 : 3/4 :
1 : Check : 10.23 : 10.30 : 10.3A :10.6l : 9.85 :
2 : A oz. MHBOL/ : 11.20 : 10.38 : 10.19 : 9.99 : 10.19 :
3 : 8 oz. MR 30 : 10.76 : 10.39 : 10.55 :10.2A : 9.79 :
A : 1 1b. MB 30 : 10.33 : 10.50 : 10.AA :10.70 : 10.55 :
5 : 5 lbs. NH 30 : 10.61 : 10.A6 : 10.65 :10.A6 : 10.60 :
6 : 20 lbs. NH 30 : 10.56 : 10.59 : 11.13 :10.A2 : 10.52 :
7 : A oz. 2,A-D : 10.6A : 10.53 : 10.39 :10.A1 : 10.17 :
8 : 8 oz. 2,A-D : 10.73 : 9.75 : 10.36 : 9.88 : 10.09 :
9 : 1 1b. 2,A-D : 10.78 : 10.64 : 10.61 :10.20 : 10.23 :
10 : 2 lbs. 2,A-D : 11.10 : 10.73 : 10.37 :10.81 : 10.43 :
Mean of all treatments : 10.70 : 10.43 : 10.50 :10.39 : 10.2A :
Least significant difference needed for comparison at the:
5-percent level 0.87 : 0.94 : 0.95 : 0.95 : 0.97 :
l-percent level 1.17 : 1.25 : 1.27 : 1.26 : 1.30 :

1
Maleic hydrazide

 

 

 

 

Table 5. Continued

3/12 3 3/18 : 3/27 : h/7 : 4/17 : A/28 = 5/9 : MBan
10.82 : 10.47 : 10.05 : 11.76 : 10.33 : 11.98 : 11.7. : 10.70
10.58 : 10.80 : 10.3A : 11.52 : 11.70 : 11.86 : 12.20 : 10.91

9.99 : 11.03 : 9.97 : 11.51 : 11.25 : 10.84 : 11.87 : 10.68
10.55 : 11.31 : 10.29 : 11.15 : 11.55 : 11.56 : 12.05 : 10.92
10.43 : 9.79 : 10.32 : 11.08 : 11.38 : 11.66 : 11.66 : 10.76
10.74 : 10.51 : 10.19 : 10.97 : 11.61 : 12.15 : 11.73 : 10.92
10.32 : 10.87 : 10.44 : 11.59 3 11.63 : 11.45 : 11.h5 3 10.82
10.96 : 10.70 : 10.34 3 11.83 : 11.73 : 11.91 : 11.08 : 10.78
10.88 : 10.39 : 10.28 : 11.58 : 12.04 : 11.90 : 11.62 : 10.93
10.81 : 10.85 : 10.48 : 11.90 : 12.09 : 12.31 : 12.16 : 11.17
10.60 : 10.67 : 10.27 x 11.A9 : 11.53 = 11.76 : 11.75 : 10.86
0.82 : 0.92 : 1.13 : 0.88 : 1.15 : 1.25 : 0.49

1.09 : 1.23 : 1.51 : 1.18 : 1.53 : 1.67 : 0.66

DISCUSSION

In discussing the results of these experiments it
should be noted that findings of the experiments were mainly
based on chemical analysis of the juices sampled.

For the first two experiments, Rio Piedras and Humacao,
in general, the difference between the means for Brix, polari-
zation, purity, available 96 degrees sugar percent cane yields,
and tons of cane to the acre are not significant. This pre-
liminary attempt to alter the metabolism.of the sugar cane
plant at harvest time was not successful as evidenced by the
data presented in Tables No. 1 and No. 2. It was felt that
perhaps applications in large dosages of 2,4D did not affect
the metabolic activity of the cane plant as did smaller doses
used by Beauchamp (1). However, other factors may be of imp
portance, such as the physical prOperties of the chemical used.
In the literature available there is no mention to anything
concerning the pH, wettability, rate of absorption by the plant,
and other properties of the chemical used, which may have a
decisive importance in the final results obtained.

Additional work was undertaken to determine daily
fluctuations in available 96 degrees percent cane yields after
applications of 2,4D with smaller dosages. After tracing the
daily fluctuations for sucrose for 15 consecutive days, and
thereafter every five to seven days for more than one and a half

months, no significant differences were observed between the

23

means of the various treatments.

Further refinements in the dosages with 2,AD were tried
in the Gurabo experiment. There were no significant differences
between the means of the treatments. The same holds true for
the means of the treatments using maleic hydrazide. The yields
from.the plots receiving a 0.20 percent solution of 2,4D were
quite consistently higher throughout the harvesting period than
those from.the check plots, but the differences were not signif-
icant even at the 5 percent level. There were some definite
high and low sucrose levels during the harvesting season, but
through the season as a whole the canes from.the treated plots
were more uniform.in the sucrose content than those of the
check plots. This trend is shown in Graph No. 2.

A general inspection of the data indicates that the daily
variations in the sucrose content throughout the harvesting sea-
son were attributable rather to weather, or other conditions,
than to treatments. In conclusion, the evidence of the experi-
mental data, in Puerto Rico, to this date, is rather discouraging
for the use of plant growth regulators, such as 2,4D and maleic
hydrazide, in an effort to affect the composition of the green

leaf-millable stalks of the cane at harvesting.

SUEEARY

Data are presented here on the effect of applications
of 10, 20, and 30 pounds to the acre of the sodium.salt of 2,4D,
acid basis, at three intervals, 10, 20, and 30 days, prior to
harvest. Field experiments were conducted at Rio Piedras and
Humacao following a randomized block layout. Each treatment
'was replicated six.times. The mean available 96 degrees sugar
percent cane yields was 12.2 at both locations with very small
deviations above or below it. No significant differences were
observed between the mean Brix, polarization, purity, available
96 degrees sugar percent cane yields, and tons of cane to the
acre at either location.

Data are presented from further experiments on the effect
of the application of smaller dosages of 2,4D and maleic hydra-
zide to the sugar cane plant at varying intervals prior to har-
vest time. Field experiments were conducted again in Rio Piedras
in northern Puerto Rico and at Colonia Rio Grande, between Caguas
and Gurabo, in east-central Puerto Rico. Daily fluctuations in
Brix, polarization, purity, and available 96 degrees sugar per-
cent cane yields were followed for A6 and 72 day periods, respec-
tively. No significant differences were observed between the
mean available 96 degrees sugar percent cane yields that could
be ascribed to treatments. Seasonal variations attributable to
weather conditions may have been rather important factors at

both locations.

25

1.

2.

3.

A.

5.

7.

9.

10.

ll.

LITERATURE CITED

Beauchamp, C. E. Effects of 2,4D on sugar content of

sugar cane, Sugar J. 13 (5) 57-70, Oct. 1950;
13 (6) 20-30, Nov. 1950.

Currierr, H. B., Day, B. E., and Crafts, A. S. Some
effects of maleic hydrazide on plants, Botg Caz.
112 (3) 272-80, 1951.

De Oliviera, B. D., g§.§1., Expeirmentos para aumentar
o teor em sacarose da nana de azucar, Report of
the Brazilian observers on experiments of Dr. C.

E. Beauchamp, Brazil Azucareiro. 37 (h) 92-6,
1951.

Loustalot, A., Cruzado, J. H., and anik, T. J. The
effect of 2,AD on the sugar content of sugar cane,

Sggar J. 13 (5) 78. 1950.

McIlrath, W. J., Response of the cotton plant to maleic
hydrazide, Am. J. Bot. 37 (10) 816-19, 1950.

Naylor, A. W., and Davis, E. A., Some effects of maleic
hydrazide on growth and respiration of representative
monocots and dicots, Proc. Am. Soc. Plant Physigl.
(2Ath. meeting), abstracts p. 13, Dec. 1949.

Naylor, A. W., and Davis, E. A., Maleic hydrazide as a
plant growth inhibitor, Bot. Gaz. 112 (1) 112-26,
1950.

Peto, F. H., §§H§;., Effects of preharvest sprays of
maleic hydrazide on sugar beets, Am. Soc. Sugar
Beet Tech., abstracts p. A, Salt Lake City, Feb.,
1952.

Pipes, F., Hormones to increase yields, edit., Sugar J.
12 (8) 3. 1950.

Ririe, D., and Mikkelson, D. 3., The effect of maleic
hydrazide on sugar beet growth and sucrose content
in certain field experiments, Am. Soc. Sugar Beet
Tech., abstracts p. 3, Salt Lake City, Feb., 1952.

Stout, M., Two years results evaluating effect of pre-
harvest sprays of maleic hydrazide on respiration
and spoilage of sugar beets. Am. Soc. Sugar Beet
Tech., abstracts p. A, Salt Lake City, Feb., 1942.

26

27

12. Wittwer, S. H., and Hansen, C..M., Progress report on
the effects of preharvest foliage sprays of maleic
hydrazide on storage losses of sugar beets, paper
presented at meeting of Am. Soc. of Sugar Beet
Tech., Detroit, Jan. 25, 1951.

13. Wbrt, D. J., Effects of nonlethal concentrations of
2,hD on buckwheat, Elant Physiol. 26 (1) 50-7,
1950.