Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

doi:10.4236/ajps.2012.39160

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American Journal of Plant Sciences, 2012, 3, 1328-1335

http://dx.doi.org/10.4236/ajps.2012.39160 Published Online September 2012 (http://www.SciRP.org/journal/ajps)

Changes in the Ovarian Polyamine Content and Seed Set

Efficiency of Cotton by the Plant Growth Regulator BM86

Androniki C. Bibi, Derrick M. Oosterhuis, Evangelos D. Gonias

Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, USA.

Email: [email protected]

Received June 7th, 2012; revised July 6th, 2012; accepted July 19th, 2012

ABSTRACT

Naturally occurring polyamines in plants have been implicated in floral initiation, and fruit development. The plant

growth regulator BM86 was formulated to stimulate seed production and fruit growth by enhancing polyamine synthe-

sis. The objectives of this study were to determine the effect of BM86 on free polyamine content in cotton (Gossypium

hirsutum L.) ovaries and on seed set efficiency, and also to investigate genotypic differences in ovarian polyamine con-

tent. BM86 was applied at the first flower stage and two weeks later at 2.34 mL/ha. This study showed that application

of BM86 had a significant positive effect on ovarian polyamine content of cotton. Putrescine and spermidine one week

after the 1st BM86 application and putrescine two week after the 1st BM86 application, were significantly increased

compared to the untreated control. Higher seed set efficiency with the BM86 application was observed when the total

number of seeds was used for the calculation. However, when the number of harvestable seeds was used to calculate

seed set efficiency BM86 had no significant effect. In addition, application of BM86 did not significantly alter seedcot-

ton yield of the crop. Only small differences in ovarian polyamine content were detected among the genotypes tested,

possibly due to the narrow genetic pool of the commercial cotton genotypes used. Application of BM86 can signifi-

cantly increase cotton seed number by enhancing polyamines biosynthesis, but further research is needed to determine

how to capitalize on the increased potential number of harvestable seeds.

Keywords: Putrescine; Spermidine; Spermine; BM86; Gossypium hirusutm L.; Ovaries

1. Introduction

Cotton (Gossypium hirsutum L.) is a major industrial

crop grown for fiber, fuel, and feed, but yield suffers

from various biotic and abiotic stresses during the repro-

ductive development. The number of seed per boll is an

important basic component of both cotton yield and fiber

quality. Seed number is a function of the number of lo-

cules (carpels) per boll and the number of ovules per

locule [1] (Stewart 1986). Several factors such as the

lack of seed fertilization, post-fertilization termination of

embryo growth, cultivar and environment can contri-

buted to the variation in the number of seed per boll [2]

(Turner et al. 1977).

Polyamines are organic polycations involved in DNA

replication and cell division [3] (Bais and Ravishankar

2002), and they are intimately involved in successful re-

productive development of the crop, cell multiplication

and cell differentiation during organogenesis [4] (Costa

et al. 1984). Polyamines can act as regulators of many

physiological processes including flower induction [5-9]

(Evans and Malmberg 1989; Faust and Wang 1992;

Bagni et al. 1993; Bouchereau et al. 1999; Kakkar and

Sawhney 2002). According to Costa et al. (1984) [10]

polyamines play an important role in flowering, pollina-

tion and early fruit development. Kloareg et al. (1986)

[11] indicated that polyamines are indispensable to plants

at the time of flowering and early fruit development.

The documented importance of polyamines in repro-

ductive development directed many researchers to exo-

genously applying polyamines in an effort to enhance

fruit development. Reports in mango (Mangifera indica

L.) [12] (Singh and Janes 2000) and apricot (Prunus ar-

meniaca L.) [13] (Alburquerque et al. 2006) showed im-

proved fruit retention and yield. However, exogenous

application of polyamines in row crops is not a practical

management practice due to the high cost of the material.

An affordable alternative is to apply synthetic plant

growth regulators.

The plant growth regulator BM86 (active ingredient

GA14; Goëmar Laboratories, Saint-Malo, France) is an

elicitor that contains oligosaccharides reported to re- gu-

late the synthesis of endogenic polyamines. Broquedis et

al. (1995) [14] investigated the effect of GA14 on the

composition of polyamines in grapes (Vitis vinifera L.),

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86 1329

and showed an increase in the accumulation of poly-

amines particularly at the end of the first stage of fruit

development. Treatment with GA14 increased the num-

bers, weight and growth of the fruit, and this was related

to a significant increase in polyamine content in the

flowers and in the fruit. It appears, therefore, that the

BM86 contains elicitors which stimulate the metabolism

of polyamines of endogenous growth.

Numerous anecdotal reports with horticulture plants

have shown that BM86 acts to stimulate reproductive

development of the plant. According to these reports

(Anonymous 2008) [15] BM86 increased yield and oil

production of olives (Olea europeae L.), promoted uni-

form fertilization and fruit set in grapes (Vitis vinifera L.)

and resulted in increased fruit size and total yield in cit-

rus (Citrus sp. L). In cotton there is a single report that

associates BM86 application with increased yield [16]

(Rethwisch 2006). However, there are no reports that

examine the effect of BM86 on polyamines in cotton.

Therefore in this study it was hypothesized that poly-

amine concentration in cotton ovaries will increase with

the application of BM86 and this will result in increased

seed set efficiency of cotton. Also, it was hypothesized

that genotypic differences in cotton will exist. The objec-

tives were to determine the effect of the BM86 on free

polyamines in cotton ovaries, and seed set efficiency of

cotton, and to investigate genotypic differences in ovule

polyamine content

2. Material and Methods

2.1. Plant Establishment

A field study was conducted at the Lon Mann Cotton

Research Station in Marianna Arkansas (34˚5'N, 90˚5'W)

in 2005 and 2006. The cultivars used were DP444BR,

ST5599BR, and FM960BR. The soil was a Captina silt

loam (typical fragiudult). The experimental plot size was

four rows by 15m and the plant population 10 plants per

m2. The study was furrow-irrigated based on an irrigation

scheduler program [17] (University of Arkansas Coo-

perative Extension Database Service 2007). The fertiliza-

tion program was determined by preseason soil tests and

recommended values for cotton. Weed and insect control

were conducted according to Arkansas extension recom-

mendations. At first flower BM86 (Goëmar Laboratories,

Saint-Malo, France) was applied to the right 2 rows of

each plot at 2.34 mL/ha (recommended rate from Goë-

mar Laboratories) with a backpack CO2 sprayer cali-

brated to deliver 94 L/ha of spraying solution. The left

two rows were used as the control. The day before the 1st

application of BM86, the flowering node was determined

and 10 first-sympodial fruiting position white flowers

were collected from each plot. Sampling was performed

weekly using first-position flowers two nodes higher than

the previous position, for a total of three weeks. BM86

was reapplied two weeks after the first application.

2.2. Number of Ovules/Ovary

Half of the flowers that were collected were used to de-

termine the number of ovules per ovary. The procedure

involved separating the ovary from the petals and sepals

and dissecting the ovaries to determine the number of

ovules in each ovary.

2.3. Polyamines Analysis

Chemical: Putrsecine dihydrochloride, spermidine trihy-

drochloride, spermine tetrahydrochloride, hexamethyla-

nediamine, dansyl chloride, 99.9% acetone, and sodium

carbonate were purchased from Sigma Aldrich.

Extraction of Tissues: Polyamines were extracted

based on Smith and Davies [18] (1985) with modifica-

tions needed for cotton. Cotton ovaries were separated

from petals and sepals. Ovary tissue (0.1 g) was homoge-

nized in mortars with pestles in 0.2 N HClO4. For unfor-

tified samples, 100 μL 1 mM hexamethylanediamine in

0.2 N HClO4 was added to the tissue prior to the ho-

mogenization as an internal standard. The final volume

of 2 mL was obtained by adding 1900 μL 0.2 N HClO4.

For the fortified samples, 100 μL 1 mM hexanediamine

in 0.2 N HCLO4 was added plus the desired volume of

fortification solution in 0.2 N HClO4, which was 120 μL

1 mM of Putrescine in 0.2 N HClO4, 120 μL 1 mM Sper-

midine in 0.2 N HClO4, and 120 μL 1mM of Spermine in

0.2 N HClO4. The final volume of 2 mL was obtained by

adding 1540 μL 0.2 N HClO4. An aliquot of 1.5 mL of

the homogenate was transferred to 2 mL plastic micro

centrifuge tubes and the samples were centrifuged at 4˚C

for 20 minutes at 13,000 rpm.

Dansylation: The polyamines were derivatized by

adding 50 μL aliquots of the supernatant to 500 μL 21.2

mM aqueous Na2CO3, 200 μL 99.9% acetone, and 50 μL

of 12.5 mM dansyl chloride in acetone. The mixture was

incubated in a thermal reaction block at 60˚C for 1h in

the dark. After 1 h in the thermal block the samples were

removed and cooled to near room temperature, and 50 μL

of 1 N HClO4 was added to the mixture and mixed. The

samples were then centrifuged at 4˚C for 20 minutes at

13,000 rpm after which 700 μL of centrifugate was trans-

ferred into 2 mL sample vial and 700 μL of 0.02 N

HClO4 was added. The samples were capped and mixed

before injection into the High Performance Liquid Chro-

matography (HPLC). Derivatization needs to be in a ba-

sic solution, whereas the final solution for HPLC needs

to be acidic.

Standard Preparation: A total of six standards were

used for the preparation of the standard curves. The stan-

dards included putrescine, spermidine, spermine and the

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

1330

internal standard hexamethylanediamine. The concentra-

tion of putrsecine and spermidine in the six standards

ranged from 30 to 1 nmole/mL, while the concentration

of spermine ranged from 60 to 2 nmole/mL. A 500 μL

aliquot of 1mM hexamethylanediamine was added to the

first five standards, while an amount of 1.25 mL of 1mM

hexamethylanediamine was added to the last one. The

final volume was 10 mL for the first five standards and

25 mL for the final standard. To bring the standards to

the final volume 0.2 N HClO4 was used.

HPLC Analysis: HPLC analysis was performed in a

Hitachi HPLC (Hitachi High Technologies America, Inc.,

Canada) system that included a model L-7100 pump, an

L-7200 autosampler, a D-7000 interface, and an ERC-

3415a degasser, and an L-7480 fluorescence detector.

The column used in this analysis was a 25 cm × 2 mm id

0.5 micron Phenomenex Gemini C18. Injection volume

was 40 μL. Polyamines were eluted from the column at

0.3 mL/min with a methanol:water (v/v) gradient from

70% methanol to 95% methanol over 6 min and then

remaining at 95% methanol for 16.4 min. The system

was re-equilibrated with 70% methanol for 15 min before

the next injection. For dansyl polyamines, an excitation

wavelength of 365 nm was used with an emission wave-

length of 510 nm. Data collection and processing was

with Hitachi System Manager (HSM) software on the

internal standard concentration.

2.4. Seed Set Efficiency (SSE) and Seedcotton

Yield

At harvest five bolls were hand-picked from each plot

from the same node from which flowers had been previ-

ously collected, for both control and BM86 treated plants.

The final number of seed per boll was determined from

the hand-picked bolls, and seed set efficiency was calcu-

lated using the equation: [seed set efficiency = (# of

seeds/# of ovules) × 100]. In a cotton boll at harvest there

are undeveloped ovules and harvestable seeds. For our

experiments seed set efficiency was calculated using both

the total seed number (undeveloped ovules + harvestable

seeds) and the number of the harvestable seeds. Seedcot-

ton yields were determined by mechanically harvesting

each individual sub-plot.

2.5. Statistical Analysis

The experimental design was a randomized complete

block (RCBD) with five replications. The treatment de-

sign was split-plot in strips (split-block) with main factor

being “cultivars” that were randomly assigned to the ex-

perimental plots, and sub-factor being “BM86 applica-

tion” that was not randomly assigned to allow easier

harvest. The year effect was considered random and not

included in the model. Data from each year was analyzed

and presented separately. Statistical analysis was per-

formed with the JMP 6 Software (SAS Institute Inc.,

Cary, NC). Interactions and main effects were tested with

Analysis of Variance (ANOVA) at α ≤ 0.05, when sig-

nificant effects were detected means were separated with

Student’s t-test (α ≤ 0.05).

3. Results

The analysis of the data showed no significant “cultivar ×

BM86 × year” interaction therefore “cultivar × BM86

application” was analyzed separately for each years of

the study for each parameter measured. In addition there

was no significant “cultivar × BM86 application” inter-

action in either year (Table 1). The lack of interaction

allowed us to analyze the main effects of “nodal posi-

tion” and “BM86 application” on putrescine spermidine,

spermine, seed set efficiency (calculated with the total

seed number), seed set efficiency (calculated with the

harvestable seed number), and seedcotton yield.

3.1. Effect of BM86 Application on Ovarian

Polyamine Content

One week after the 1st BM86 application: Ovarian putre-

scine concentration was significantly increased compared

to the untreated control plant in 2005 (P = 0.0047; Fig-

ure 1(A)). However, application of BM86 did not sig-

nificantly affect spermidine and spermine concentration

with P = 0.3927 and P = 0.9337, respectively (Figure

1(I)). These data were further supported in 2006 where

again one week after the BM86 application the putre-

scine content was significantly higher compared to the

control (P = 0.0390; Figure 1(II)). In addition in 2006

the BM86 application significantly increased the sper-

midine content of cotton ovaries (P = 0.0094), but again

the effect on spermine was not significant (P = 0.3791)

(Figure 1(B)).

Two weeks after the 1st BM86 application: The putre-

scine content of cotton ovaries continued to be signifi-

Table 1. The statistical significant for the “cultivar × BM86

application” interaction of all the parameters measured in

2005 and 2006.

“Cultivar × BM86 application”

Variables measured 2005 2006

Putrescine 0.17 0.57

Spermidine 0.99 0.46

Spermine 0.19 0.24

Seed set efficiency (total seed

number) 0.54 0.26

Seed set efficiency (harvestable

seed number) 0.99 0.59

Seedcotton yield 0.64 0.46

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

1331

Putrescine

Spermine

Spermidine

BM86

CONTROL

0 500 1000 1500 2000 2500

nmoles/g fresh wt

Putrescine

Spermine

Spermidine

BM86

CONTROL

0 500 1000 1500 2000 2500 3000

nmoles/g fresh wt

(I) (II)

Figure 1. The effect of the plant growth regulator BM86 polyamine concentration of cotton ovaries one week after the first

BM86 application in 2005 (I) and 2006 (II). Pair of columns for each polyamine with the same letter are not significantly dif-

ferent for α = 0.05 (± 1 std error bars are shown).

3.3. Effect of Cultivars on Ovarian Polyamine

Content

cantly increased compared to the untreated control plant

(P = 0.0492; Figure 2(I)). However the BM86 applica-

tion did not significantly affect either spermidine or sper-

mine concentration (P = 0.0643 and P = 0.2852, respec-

tively) (Figure 2(I)). Similar effects of BM86 were re-

corded in 2006 with the putrescine content significantly

higher compared to the control (P = 0.0192; Figure

2(II)), and spermidine and spermine concentration not

significantly affected (P = 0.0611 and P = 0.2539, re-

spectively) (Figure 2(II)).

One week after the 1st BM86 application: In 2005 the

cultivar effect was not significant for putrescine (P =

0.5119), spermidine (P = 0.1812), or spermine (P =

0.3451) (Table 2). In 2006 there were no cultivar diffe-

rences for putrescine and spermine (P = 0.1926 and P =

0.2767, respectively), but there were differences for sper-

midine (P = 0.0439) (Table 2). Among the genotypes

tested, FM960BR showed significantly higher ovarian

spermidine content compared to DP444BR and ST5599-

BR.

One week after the 2nd BM86 application: The BM86

application did not significantly affect any of the three

polyamines quantified in 2005 (Figure 3(I)). The P-values

for putrescine, spermidine, and spermine were P = 0.5529,

P = 0.0717, and P = 0.2273, respectively. In 2006, one

week after the BM86 application the ovarian putrescine

content was not significantly altered (P = 0.1780; Figure

3(II)), whereas the spermidine concentration of cotton

ovaries significantly increased compared to the untreated

control (P = 0.0124). Spermine was not detected in cot-

ton ovaries one week after the 2nd BM86 application.

Two weeks after the 1st BM86 application: In 2005, the

putrescine, spermidine and spermine concentrations of

cotton ovaries did not differ significantly among the cul-

tivar (Table 3). In 2006 there were cultivar differences

for putrescine and spermine (P = 0.0087 and P = 0.0369

respectively), but the spermidine concetration was not

significantly changed (P = 0.1499) (Table 3). Among the

genotypes tested FM960BR showed significantly higher

ovarian putrescine content compared to DP444BR and

ST5599BR, and DP444BR showed significantly higher

spermine concentration compared to ST55899BR.

3.2. Effect of BM86 Application on Seed Set

Efficiency and Seedcotton Yield

One week after the 2nd BM86 application: In 2005,

there were no cultivar differences for spermidine and

spermine concentration of cotton ovaries (Table 4).

However the cultivar effect was significant for putrescine

concentration (P = 0.0349). Among the genotypes tested

FM-960BR and ST5599BR showed significantly higher

putrescine compared to DP444BR. In 2006 neither putre-

scine nor spermidine concentration of cotton ovaries

were significantly affected by the cultivar effect with P =

0.1780 and P = 0.9024, respectively (Table 4).

In 2005 BM86 application significantly increased the

seed set efficiency of cotton when calculated using the

total number of seeds (P = 0.0423; Figure 4(I)), however

application of BM86 did not significantly affect seed set

efficiency when it was calculated with just the number of

harvestable seeds (P = 0.3287). Similar data were ob-

served in 2006, the seed set efficiency calculated by the

total seed number was significantly increased after BM86

application (P = 0.0046; Figure 4(II)), while when cal-

culated with just the number of harvestable seeds the

effect was not significant (P = 0.7434). The non-signifi-

cant effect of BM86 application on seed set efficiency

(i.e. of harvestable seeds) was reflected in the non-signi-

ficant effect on seedcotton yield in either year of the

study (Figure 5).

3.4. Effect of Cultivars on Seed Set Efficiency

and Seedcotton Yield

There were no cultivar differences in 2005 and 2006 for

seed set efficiency calculated by the total seed number

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

1332

Putrescine

Spermine

Spermidine

BM86

CONTROL

0 500 1000 1500 2000 2500

nmoles/g fresh wt

Putresc ine

Spermin e

Spermi dine

BM86

CONTROL

0 500 1000 1500 2000 2500 3000

nmoles/g fresh wt

(I) (II)

Figure 2. The effect of the plant growth regulator BM86 on the polyamine concentration of cotton ovaries two weeks after the

first BM86 application in 2005 (I) and 2006 (II). Pair of columns for each polyamine with the same letter are not significantly

different for α = 0.05 (± 1 std error bars are shown).

Putrescine

Spermine

Spermidine

BM86

CONTROL

0 500 1000 1500 2000 2500

nmoles/g fresh wt

Putrescine

Spermine

Spermidi n e

BM86

CONTROL

0 500 1000 1500 2000 2500 3000

nmoles/g fresh wt

(I) (II)

Figure 3. The effect of the plant growth regulator BM86 polyamine concentration of cotton ovaries one week after the second

BM86 application in 2005 (I) and 2006 (II). Pair of columns for each polyamine with the same letter are not significantly dif-

ferent for α = 0.05 (± 1 std error bars are shown).

100

Total Seed NumberHarvestable seeds

Seed Set Efficien cy (%)

CONTROL

BM86

100

Total Seed NumberHarvestable seed s

Seed Set Efficiency (%)

CONTROL

BM86

(I) (II)

Figure 4. The effect of BM86 on seed set efficiency of cotton in 2005 (I) and 2006 (II). Pairs of columns with the same letter

are not significantly different for α = 0.05 (± 1 std error bars are shown).

and in seed set efficiency calculated by the harvestable

seed number (Table 5). In addition, the cultivar effect

was not significant for seedcotton yield in either year of

the study with P = 0.2209 (2005) and P = 0.6572 (2006)

(Table 6).

4. Discussion

This study showed that application of BM86 had a sig-

nificant positive effect on ovarian polyamine content of

cotton. The results were positive for putrescine and

spermidine one week after the 1st BM86 application and

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86 1333

500

1000

1500

2000

2500

3000

3500

4000

4500

2005 2006

Year

Seedcotton (kg/ha)

CONTROL

BM86

Figure 5. The effect of BM86 on seedcotton yield in 2005

and 2006. Pair of columns within a year with the same letter

are not significantly different for α = 0.05 (± 1 std error

bars are shown).

and for putrescine two weeks after the 1st BM86 applica-

tion. Broquedis et al. (1995) [14] investigated the effect

of GA14, the active ingredient in BM86, and showed an

increase in the accumulation of polyamines in grapes

(Vitis vinifera L.). In addition, there are several anecdotal

reports in horticulture crops that associate the BM86 ap-

plication with increased polyamine levels; however this

is the first documented report of increased polyamines in

cotton ovaries. Among the genotypes tested only FM-

960BR showed increased polyamine content, however

this was not consistent from year to year. Polyamines

have been quantified in diverse rice cultivars [19] (Lepri

et al. 2002), while post-harvest changes in polyamines

have been measured in two diverse rose species [20]

(Sood and Nagar 2008). This is the first report of cotton

cultivar screening for polyamines in ovarian tissue after

Table 2. Cultivar effect on ovarian polyamine content one week after the 1st application of BM86 in 2005 and 2006.

Putrescine Spermidine Spermine

2005 2006 2005 2006 2005 2006

Cultivars

nmoles/g fresh wt

DP444BR 1300.3 a1 1403.5 a862.1 a 853.1 b187.1 a 517.3 a

FM960BR 1750.8 a 1461.9 a1105.3 a 1320.6 a196.7 a 682.9 a

ST5599BR 1442.2 a 1074.5 a883.6 a 979.9 b157.1 a 528.6 a

P-Value 0.5119 0.1926 0.1812 0.0439 0.3451 0.2767

1Cultivars with the same letter in a column are not significantly different for α = 0.05.

Table 3. Cultivar effect on ovarian polyamine content two weeks after the 1st application of BM86 in 2005 and 2006.

Putrescine Spermidine Spermine

2005 2006 2005 2006 2005 2006

Cultivars

----------nmoles/g fresh wt---------

DP444BR 590.1 a1 904.8 b431.9 a 273.2 a 128.3 a 125.5 a

FM960BR 609.4 a 1337.6 a472.7 a290.7 a 144.4 a 111.7 ab

ST5599BR 640.9 a 975.6 b405.5 a 253.8 a 120.7 a 103.6 a

P-Value 0.7463 0.0087 0.3135 0.1499 0.9632 0.0369

1Cultivars with the same letter in a column are not significantly different for α = 0.05.

Table 4. Cultivar effect on ovarian polyamine content one week after the 2nd application of BM86 in 2005 and 2006.

Putrescine Spermidine Spermine

2005 2006 2005 2006 2005 2006

Cultivars

----------nmoles/g fresh wt---------

DP444BR 106.8 b1 79.9 a 479.4 a34.1 a 21.4 a -

FM960BR 157.3 a 145.4 a 872.2 a30.5 a 25.9 a -

ST5599BR 163.8 a 137.2 a 822.9 a31.9 a 30.2 a -

P-Value 0.0349 0.1780 0.2813 0.9024 0.6550 -

1Cultivars with the same letter in a column are not significantly different for α = 0.05.

Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

1334

Table 5. The effect of cultivars on seed set efficiency of cotton calculated by the total seed number and by the number of the

harvestable seeds in 2005 and 2006.

Cultivars Seed Set Efficiency

2005 2006

Seed Record

Total seed number DP444BR 70.3 a1 80.9 a

FM960BR 66.4 a 77.7 a

ST5599BR 76.3 a 80.7 a

P-Value 0.0584 0.4405

Harvestable seeds DP444BR 88.0 a 97.5 a

FM960BR 87.4 a 98.8 a

ST5599BR 91.3 a 96.3 a

P-Value 0.3008 0.4386

1Cultivars in a column for each parameter with the same letter are not significantly different for α = 0.05.

Table 6. The effect of cultivars on seedcotton yield of cotton

for 2005 and 2006.

Cultivars Seedcotton

2005 2006

kg/ha

DP444BR 3839.8 a1 3158.3 a

FM960BR 3692.6 a 3155.6 a

ST5599BR 4056.2 a 2989.9 a

P-Value 0.2209 0.6572

1Cultivars in a column with the same letter are not significantly different for

α = 0.05.

BM86 application.

Polyamines have been associated with fruit set and the

initial phase of fruit development in many horticulture

plants, such as apple (Malus domestica L.) [10,21] (Costa

and Bagni 1983; Biasi et al. 1991), pear (Pyrus commu-

nis L.) [22,23] (Crisosto et al. 1986; Crisosto et al. 1988),

pepper (Capsicum annuum L.) [24] (Serrano et al. 1995),

olive (Οlea europeae L.) [25] (Rugini and Mencuccini

1985), mango (Mangifera indica L.) [26] (Singh and

Singh 1995), and tomato (Solanum lycopersicum L.) [27]

(Antognoni et al. 2002). This can be attributed to a pos-

sible involvement of polyamines in cell growth [3] (Bais

and Ravishankar 2002). Therefore the increased levels of

polyamines reported in our study were expected to result

in improved seed set. Higher seed set efficiency with the

BM86 application was observed when the total number

of seeds was used for the calculation. However, when the

number of harvestable seeds was used to calculate seed

set efficiency BM86 did not have a significant effect. In

addition, BM86 application did not significantly alter

seedcotton yield of the crop. These data suggest that

BM86 application may set the potential for higher seed

set efficiency, but the cotton crop in Arkansas does not

have the resources to develop the set seeds to harvestable

seeds. In other locations such as California, higher cotton

yields after application of BM86 [16] (Rethwich 2006)

are possibly due to the higher productive environment

[28] (Gonias et al. 2008). The lack of significant diffe-

rences among the genotypes tested can be attributed to

the narrow genetic pool of the current commercial geno-

types.

5. Acknowledgements

The authors would like to acknowledge Dr. John Mattice

for the significant help with the HPLC analysis.

REFERENCES

[1] J. McD. Stewart, “Integrated Events in Flower and Fruit,”

In: J. R. Mauney and J. M. Stewart, Eds., Cotton physi-

ology, The Cotton Foundation, Memphis, 1986, pp. 261-

300.

[2] J. H. Turner, J. M. Stewart, P. E. Hoskinson and H. H.

Ramey, “Seed Setting Efficiency in Eight Cultivars of

Upland Cotton,” Crop Science, Vol. 17, No. 5, 1977, pp.

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Published online 24 October 2011.