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Extension Cotton Specialists Working Group Presenting: Darrin Dodds

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1 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: Darrin Dodds

2 Extension Cotton Specialists Working Group
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 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

3 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 Jost et al. 2006

4 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

5 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)

6 Boll size (g/boll) Main Stem Node 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)

7 Shading of the Lower Canopy
Excessive shading can decrease micronaire of lower bolls (Eaton and Ergle 1954) Boll rot Penetration of pesticides

8 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 Fishel 2006

9 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 plant Hake et al. 1991 Mepiquat only affects new growth

10 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

11 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.

12 PGR Applications and Cotton Yield
Yield response to mepiquat has always been inconsistent Biles and Cothren 2000 Positive yield effects are more likely to occur when fruit retention is reduced and vegetative growth is excessive Cook and Kennedy 2000 Yield reductions more likely to occur when excessive rates of mepiquat are applied to stressed cotton

13 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

14 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

15 Varieties Planted Region States Variety Southeast NC, TN, VA
AL, GA, SC DP 117 B2RF DP 143 B2RF DP 555 BR Mid-South AR, LA, MS PHY 485 WRF Southwest OK, TX FM 9063 B2RF ST 5458 B2RF

16 Plant Growth Regulators
Mepex Mepiquat chloride 0.35 lb ai/gal Mepex Gin Out Mepiquat Chloride 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

17 *** All PGR treatments included Induce at 0.25 % v/v ***
Product Rate Application Timing Mepex fb Mepex 8 oz/A 10 oz/A MHS 2 WAIT Mepex Gin Out fb Mepex Gin Out Stance fb Stance 1.5 oz/A 2 oz/A 3 oz/A Pentia fb Pentia NAWF = 5 Induce fb Induce 0.25 % v/v Untreated *** All PGR treatments included Induce at 0.25 % v/v ***

18 Data Collection Data collected included: Total nodes
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)

19 Plant Height Prior to 1st App.

20 PGR Plant Height By Region Southeast Mid-South Southwest Mepex fb
18.7 15.1 14.7 Mepex Gin Out fb Mepex Gin Out 19.0 15.4 14.5 Stance fb Stance 18.9 14.6 19.3 14.8 15.0 14.4 Pentia fb Pentia 15.5 14.3 Induce fb Induce 19.6 15.3 15.2 Untreated 19.5

21 % of Untreated Height By Region
PGR % of Untreated Height By Region Southeast Mid-South Southwest Mepex fb Mepex 96 101 102 Mepex Gin Out fb Mepex Gin Out 98 Stance fb Stance 97 100 Pentia fb Pentia Induce fb Induce 103 Untreated

22 Plant Height Prior to 2nd App.
LSD (0.05) = 0.9 C C C B C C C A A

23 PGR Plant Height By Region Southeast Mid-South Southwest Mepex fb
28.3 27.7 20.3 Mepex Gin Out fb Mepex Gin Out 28.7 28.2 20.4 Stance fb Stance 29.8 20.0 21.2 29.1 27.9 Pentia fb Pentia 29.0 Induce fb Induce 33.3 30.3 21.8 Untreated 33.7 30.0 LSD (0.05) 1.4 1.2

24 % of Untreated Height By Region
PGR % of Untreated Height By Region Southeast Mid-South Southwest Mepex fb Mepex 84 92 93 Mepex Gin Out fb Mepex Gin Out 85 94 95 Stance fb Stance 88 99 87 Pentia fb Pentia 86 Induce fb Induce 102 100 Untreated LSD (0.05) 4 6 NSD

25 Plant Height 2 Wk After 2nd App.
LSD (0.05) = 1.2 D BCD B B BC D A A

26 PGR Plant Height By Region Southeast Mid-South Southwest Mepex fb
31.8 36.7 18.4 Mepex Gin Out fb Mepex Gin Out 32.9 38.1 18.8 Stance fb Stance 34.4 39.2 34.5 39.1 33.4 38.6 18.9 Pentia fb Pentia 37.1 18.3 Induce fb Induce 38.9 44.6 21.7 Untreated 43.9 22.0 LSD (0.05) 1.8 1.7

27 % of Untreated Height By Region
PGR % of Untreated Height By Region Southeast Mid-South Southwest Mepex fb Mepex 82 84 Mepex Gin Out fb Mepex Gin Out 87 86 Stance fb Stance 89 90 88 85 Pentia fb Pentia Induce fb Induce 100 102 Untreated LSD (0.05) 4 5 11

28 Final Plant Height LSD (0.05) = 1.5 B B B B B B A A

29 PGR Plant Height By Region Southeast Mid-South Southwest Mepex fb
31.0 40.3 38.4 Mepex Gin Out fb Mepex Gin Out 30.8 42.2 39.1 Stance fb Stance 32.7 41.3 41.7 32.5 41.8 40.0 41.5 Pentia fb Pentia 32.1 40.5 39.3 Induce fb Induce 38.3 47.1 44.3 Untreated 39.2 49.0 43.3 LSD (0.05) 1.8 2.2 3.7

30 % of Untreated Height By Region
PGR % of Untreated Height By Region Southeast 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 89 Pentia fb Pentia 82 Induce fb Induce 98 105 97 Untreated 100 LSD (0.05) 5 6 7

31 Total Nodes LSD (0.05) = 0.6 B B B B B B A A

32 PGR Total Nodes By Region Southeast Mid-South Southwest Mepex fb Mepex
17.5 19.4 Mepex Gin Out fb Mepex Gin Out 17.4 18.4 Stance fb Stance 17.7 18.8 17.8 19.0 18.5 Pentia fb Pentia Induce fb Induce 18.9 20.3 Untreated 21.3 LSD (0.05) 0.7 NSD 1.1

33 Nodes Above Cracked Boll
LSD (0.05) = NSD

34 Nodes Above Cracked Boll By Region
PGR Nodes Above Cracked Boll By Region Southeast 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 2.9 2.3 3.1 3.3 4.1 2.7 Pentia fb Pentia 4.2 2.4 Induce fb Induce 3.9 2.6 Untreated LSD (0.05) NSD 1.1

35 Lint Yield LSD (0.05) = NSD

36 PGR Lint Yield By Region Southeast 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 1315 1088 1117 1302 1042 1147 Pentia fb Pentia 1355 1136 1065 Induce fb Induce 1358 1025 1129 Untreated 1296 1034 LSD (0.05) NSD

37 Mic Staple Strength Uniformity
PGR Mic Staple Strength Uniformity Mepex fb Mepex 4.5 1.14 30.4 82.6 Mepex Gin Out fb Mepex Gin Out 4.4 82.1 Stance fb Stance 82.3 1.15 30.8 82.4 Pentia fb Pentia 30.3 Induce fb Induce 1.13 30.0 Untreated 1.12 29.9 LSD (0.05) NSD 0.01

38 PGR Mic By Region Southeast Mid-South Southwest Mepex fb Mepex 4.7 4.5
4.2 Mepex Gin Out fb Mepex Gin Out 4.6 4.1 Stance fb Stance 4.3 Pentia fb Pentia 4.4 Induce fb Induce Untreated LSD (0.05) NSD

39 PGR Staple By Region Southeast Mid-South Southwest Mepex fb Mepex 1.14
1.16 Mepex Gin Out fb Mepex Gin Out 1.11 Stance fb Stance 1.13 1.17 1.12 1.15 Pentia fb Pentia Induce fb Induce 1.09 Untreated LSD (0.05) 0.02 0.01 NSD

40 PGR Strength By Region Southeast 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 29.9 30.7 30.8 31.0 Pentia fb Pentia 31.6 29.8 Induce fb Induce 29.5 Untreated 30.3 LSD (0.05) NSD 0.8

41 PGR Uniformity By Region Southeast Mid-South Southwest Mepex fb Mepex
82.6 83.4 81.5 Mepex Gin Out fb Mepex Gin Out 81.7 83.2 81.0 Stance fb Stance 82.1 83.1 82.2 83.5 Pentia fb Pentia 82.3 81.3 Induce fb Induce 83.0 81.4 Untreated 83.3 LSD (0.05) NSD

42 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

43 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

44 Questions


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