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Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting: Darrin Dodds

Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

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Page 1: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Efficacy and Agronomic Impacts of Commercially Available Plant Growth

Regulators Across the Cotton Belt

Extension Cotton Specialists Working Group

Presenting: Darrin Dodds

Page 2: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Extension Cotton Specialists Working Group

• Auburn University• Charles Burmester• Dale Monks

• University of Arkansas• Tom Barber

• University of Georgia• Steve Brown

• University of Florida• David Wright

• University of California – Davis• Bob Hutmacher

• Louisiana State University• Sandy Stewart

• North Carolina State University• Keith Edmisten

• Oklahoma State University• J.C. Banks

• Clemson University

• Mike Jones

• University of Tennessee

• Chris Main

• Texas AgriLife Extension Service

• Randy Boman

• Robert Lemon

• Virginia Tech

• Joel Faircloth

• University of Arizona

• Randy Norton

• Mississippi State University

• Darrin Dodds

• Kansas State University

• Stewart Duncan

Page 3: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Jost et al. 2006

Cotton Growth Habit

• Vegetative and reproductive development occur simultaneously

• Vegetative growth necessary to support reproductive growth– Excessive vegetative growth can be

detrimental

• Excessive vegetative growth:– Increased fruit abortion– Delayed crop maturity– Yield reduction

Page 4: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Fruit Abortion

• Fruit initiates at bottom of plant and progresses upward and outward (Ritchie et al. 2004)

• Excessive vegetative growth can shade the lower canopy and lead to abscission of early fruit (Oosterhuis 2001)

– Other factors can contribute to abscission of early fruit

Page 5: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Delayed Maturity and Yield

• Loss of early fruit may be compensated for when favorable conditions exist– Compensatory growth can result in

delayed maturity (Silvertooth et al. 1999)

• Yield reductions may occur due to reduced boll size (Jones and Wells 1998)

Page 6: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Figure 1. Boll size is correlated to position on fruiting branch. First and second position bolls tend to occur more frequently and weigh more than third position bolls. (Bednarz et al., 2005)

Boll

size

(g/b

oll)

Main Stem Node

Page 7: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Shading of the Lower Canopy

• Excessive shading can decrease micronaire of lower bolls (Eaton and Ergle 1954)

• Boll rot

• Penetration of pesticides

Page 8: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Fishel 2006

What is a Plant Growth Regulator?

• Chemicals used to alter the growth of a plant or plant part

• Agricultural research with PGRs began in the 1930’s– Acetlyene and ethylene– Enhanced flower production in

pineapple

Page 9: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

How Do PGR’s Work?

• Three types of hormones are affected by foliar applied PGR’s– Gibberellins, Cytokinins, and Auxin

Taiz and Zeigler 1998

• Mepiquat reduces the concentration of gibberellic acid in the plantHake et al. 1991

• Mepiquat only affects new growth

Page 10: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Effects of PGR Application

• Reduction on total number of mainstem nodes– Reduction in internode length

Reddy et al. 1992

• Reduction in leaf area

• Shift in boll location

Page 11: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Figure 2. The effect of mepiquat on number of harvestable bolls per square meter on all sympodial branch fruiting positions at each main stem node (Kerby et al., 1986). Mepiquat generally causes a greater percentage of the total bolls to lower nodes on the plant.

 

Page 12: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Applications and Cotton Yield

• Yield response to mepiquat has always been inconsistentBiles and Cothren 2000

• Positive yield effects are more likely to occur when fruit retention is reduced and vegetative growth is excessiveCook and Kennedy 2000

• Yield reductions more likely to occur when excessive rates of mepiquat are applied to stressed cotton

Page 13: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Objectives

• Examine several commercially available PGRs– Quantify effect of PGR application

on height, yield, and fiber quality

• Use these data to further refine PGR application recommendations

Page 14: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Agronomic Information

• Studies were conducted in 19 locations over two years across the cotton belt

• Planting date, seeding rate, fertility, insect management, and harvest aid applications were based on extension recommendations for each state

• Small plot research techniques were utilized at all locations

Page 15: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Varieties PlantedRegion States Variety

SoutheastNC, TN, VAAL, GA, SC

DP 117 B2RFDP 143 B2RF

DP 555 BR

Mid-South AR, LA, MS PHY 485 WRF

Southwest OK, TXFM 9063 B2RF

DP 555 BRST 5458 B2RF

Page 16: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Plant Growth Regulators

• Mepex– Mepiquat chloride– 0.35 lb ai/gal

• Mepex Gin Out– Mepiquat Chloride– 0.35 lb ai/gal– Kinetin – cytokinin

analog

• Pentia– Mepiquat

pentaborate– 0.82 lb ai/gal– Same amount of

mepiquat as Mepex

– Stance• Mepiquat chloride• Cyclanilide

– Auxin transport and synthesis inhibitor

• 0.736 lb mepiquat chloride/gal

Page 17: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Product Rate Application TimingMepex fb Mepex

8 oz/A10 oz/A

MHS2 WAIT

Mepex Gin Out fb Mepex Gin Out

8 oz/A10 oz/A

MHS2 WAIT

Stance fb Stance

1.5 oz/A2 oz/A

MHS2 WAIT

Stance fb Stance

2 oz/A3 oz/A

MHS2 WAIT

Pentia fb Pentia

8 oz/A10 oz/A

MHS2 WAIT

Stance fb Stance fb Stance

2 oz/A3 oz/A3 oz/A

MHS2 WAIT

NAWF = 5

Induce fb Induce

0.25 % v/v0.25 % v/v

MHS2 WAIT

Untreated

*** All PGR treatments included Induce at 0.25 % v/v ***

Page 18: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Data Collection• Data collected included:

– Plant height prior to initial PGR application– Plant height prior to second PGR application– Plant height two weeks after second PGR application– Plant height at the end of the season

• Total nodes

• Nodes above cracked boll

• Yield

• Fiber quality (HVI)

Page 19: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Plant Height Prior to 1st App.

14

14.5

15

15.5

16

16.5

17

17.5

18

Hei

ght (

in)

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

Page 20: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR % of Untreated Height By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

96 101 102

Mepex Gin Out fb Mepex Gin Out

98 101 101

Stance fb Stance

97 101 101

Stance fb Stance

100 102 102

Stance fb Stance fb Stance

98 100 100

Pentia fb Pentia

98 100 100

Induce fb Induce

101 100 103

Untreated 100 100 100

Page 21: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Plant Height Prior to 2nd App.

20

22

24

26

28

30

Hei

ght (

in)

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

C C C B

C

C C A A

LSD (0.05) = 0.9

Page 22: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR % of Untreated Height By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

84 92 93

Mepex Gin Out fb Mepex Gin Out

85 94 95

Stance fb Stance

88 95 93

Stance fb Stance

88 95 99

Stance fb Stance fb Stance

87 93 95

Pentia fb Pentia

86 92 94

Induce fb Induce

99 102 100

Untreated 100 100 100

LSD (0.05) 4 6 NSD

Page 23: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Plant Height 2 Wk After 2nd App.

25

28

31

34

37

40

Hei

ght (

in)

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

D BCD

B B BC

D A A

LSD (0.05) = 1.2

Page 24: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR % of Untreated Height By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

82 84 82

Mepex Gin Out fb Mepex Gin Out

84 87 86

Stance fb Stance

89 90 89

Stance fb Stance

88 89 85

Stance fb Stance fb Stance

86 88 88

Pentia fb Pentia

85 84 85

Induce fb Induce

100 102 100

Untreated 100 100 100

LSD (0.05) 4 5 11

Page 25: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Final Plant Height

30

33

36

39

42

45

Hei

ght (

in)

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

B B B B B B A A

LSD (0.05) = 1.5

Page 26: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR % of Untreated Height By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

81 86 94

Mepex Gin Out fb Mepex Gin Out

79 90 85

Stance fb Stance

84 88 87

Stance fb Stance

84 89 90

Stance fb Stance fb Stance

84 88 88

Pentia fb Pentia

82 86 88

Induce fb Induce

98 105 97

Untreated 100 100 100

LSD (0.05) 5 6 7

Page 27: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Total Nodes

16

16.5

17

17.5

18

18.5

19

19.5

Num

ber

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

B B B B B B A A

LSD (0.05) = 0.6

Page 28: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Total Nodes By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

17.5 17.5 19.4

Mepex Gin Out fb Mepex Gin Out

17.4 17.4 18.4

Stance fb Stance

17.7 17.7 18.8

Stance fb Stance

17.8 17.8 19.0

Stance fb Stance fb Stance

17.8 17.8 18.5

Pentia fb Pentia

17.7 17.7 18.8

Induce fb Induce

18.9 18.9 20.3

Untreated 19.0 19.0 21.3

LSD (0.05) 0.7 NSD 1.1

Page 29: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Nodes Above Cracked Boll

1.5

2

2.5

3

3.5

4

Num

ber

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

LSD (0.05) = NSD

Page 30: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Nodes Above Cracked Boll By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

3.8 3.2 3.7

Mepex Gin Out fb Mepex Gin Out

4.0 3.4 2.0

Stance fb Stance

4.0 2.9 2.3

Stance fb Stance

4.0 3.1 3.3

Stance fb Stance fb Stance

4.1 3.8 2.7

Pentia fb Pentia

4.2 2.9 2.4

Induce fb Induce

4.0 3.9 2.6

Untreated 4.1 3.4 3.9

LSD (0.05) NSD NSD 1.1

Page 31: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Lint Yield

1000

1025

1050

1075

1100

1125

1150

1175

1200

1225

lbs/

acre

Mepex Mepex_GO Stance_1 Stance_2 Stance_3 Pentia Induce UT

LSD (0.05) = NSD

Page 32: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Lint Yield By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

1290 1053 1137

Mepex Gin Out fb Mepex Gin Out

1376 1102 1106

Stance fb Stance

1314 1008 1115

Stance fb Stance

1315 1088 1117

Stance fb Stance fb Stance

1302 1042 1147

Pentia fb Pentia

1355 1136 1065

Induce fb Induce

1358 1025 1129

Untreated 1296 1034 1129

LSD (0.05) NSD NSD NSD

Page 33: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Mic Staple Strength UniformityMepex fb Mepex

4.5 1.14 30.4 82.6

Mepex Gin Out fb Mepex Gin Out

4.4 1.14 30.4 82.1

Stance fb Stance

4.4 1.14 30.4 82.3

Stance fb Stance

4.5 1.14 30.4 82.3

Stance fb Stance fb Stance

4.4 1.15 30.8 82.4

Pentia fb Pentia

4.4 1.15 30.3 82.3

Induce fb Induce

4.5 1.13 30.0 82.1

Untreated 4.5 1.12 29.9 82.3

LSD (0.05) NSD 0.01 NSD NSD

Page 34: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Staple By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

1.14 1.14 1.16

Mepex Gin Out fb Mepex Gin Out

1.11 1.14 1.16

Stance fb Stance

1.13 1.13 1.17

Stance fb Stance

1.12 1.12 1.17

Stance fb Stance fb Stance

1.13 1.15 1.17

Pentia fb Pentia

1.13 1.14 1.17

Induce fb Induce

1.09 1.12 1.16

Untreated 1.09 1.11 1.15

LSD (0.05) 0.02 0.01 NSD

Page 35: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

PGR Strength By RegionSoutheast Mid-South Southwest

Mepex fb Mepex

31.3 30.4 29.7

Mepex Gin Out fb Mepex Gin Out

31.1 30.0 30.2

Stance fb Stance

31.1 29.9 30.2

Stance fb Stance

31.1 30.2 30.7

Stance fb Stance fb Stance

30.8 31.0 30.4

Pentia fb Pentia

31.6 29.8 29.8

Induce fb Induce

30.8 29.8 29.5

Untreated 30.3 29.7 29.9

LSD (0.05) NSD 0.8 NSD

Page 36: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Conclusions

• All PGR’s examined provided similar plant height reductions

• PGR application did not enhance lint yield

• Total number of nodes and NACB were similar regardless of PGR applied

Page 37: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Conclusions

• Mic and uniformity were similar whether a PGR was applied or not

• Minor differences in staple length and strength were observed

• PGR product selection should be based on individual grower needs as opposed to a specific product

• PGR application decisions should be made on a field-by-field basis each year

Page 38: Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:

Questions