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

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Presentation on theme: "Efficacy and Agronomic Impacts of Commercially Available Plant Growth Regulators Across the Cotton Belt Extension Cotton Specialists Working Group Presenting:"— Presentation transcript:

1 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 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

3 Jost et al 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

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 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/boll) Main Stem Node

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

8 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 1930s –Acetlyene and ethylene –Enhanced flower production in pineapple

9 How Do PGRs Work? Three types of hormones are affected by foliar applied PGRs –Gibberellins, Cytokinins, and Auxin Taiz and Zeigler 1998 Mepiquat reduces the concentration of gibberellic acid in the plant Hake et al Mepiquat only affects new growth

10 Effects of PGR Application Reduction on total number of mainstem nodes –Reduction in internode length Reddy et al 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 RegionStatesVariety Southeast NC, TN, VA AL, GA, SC DP 117 B2RF DP 143 B2RF DP 555 BR Mid-SouthAR, LA, MSPHY 485 WRF SouthwestOK, TX FM 9063 B2RF DP 555 BR ST 5458 B2RF

16 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 lb mepiquat chloride/gal

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

18 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)

19 Plant Height Prior to 1 st App.

20 PGRPlant Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated

21 PGR% of Untreated Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated100

22 Plant Height Prior to 2 nd App. CCCBCBC CCAA LSD (0.05) = 0.9

23 PGRPlant Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)

24 PGR% of Untreated Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated100 LSD (0.05)46NSD

25 Plant Height 2 Wk After 2 nd App. DBCDBCD BBBCBC DAA LSD (0.05) = 1.2

26 PGRPlant Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)

27 PGR% of Untreated Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance 8688 Pentia fb Pentia Induce fb Induce Untreated100 LSD (0.05)4511

28 Final Plant Height BBBBBBAA LSD (0.05) = 1.5

29 PGRPlant Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)

30 PGR% of Untreated Height By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance 8488 Pentia fb Pentia Induce fb Induce Untreated100 LSD (0.05)567

31 Total Nodes BBBBBBAA LSD (0.05) = 0.6

32 PGRTotal Nodes By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)0.7NSD1.1

33 Nodes Above Cracked Boll LSD (0.05) = NSD

34 PGRNodes Above Cracked Boll By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD 1.1

35 Lint Yield LSD (0.05) = NSD

36 PGRLint Yield By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD

37 PGRMicStapleStrengthUniformity Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD0.01NSD

38 PGRMic By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD

39 PGRStaple By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05) NSD

40 PGRStrength By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD0.8NSD

41 PGRUniformity By Region SoutheastMid-SouthSouthwest Mepex fb Mepex Mepex Gin Out fb Mepex Gin Out Stance fb Stance Stance fb Stance Stance fb Stance Pentia fb Pentia Induce fb Induce Untreated LSD (0.05)NSD

42 Conclusions All PGRs 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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