Effects of Pix at Low Rate Multiple Applications on Reproductive and Vegetative Structures in Cotton

R. Hayes, J. Jenkins, and J. MeCarty, Jr.


 
ABSTRACT

Four applications of mepiquat chloride (1,1-dimethyl- piperidinium chloride) (MC) at 0, 6.2, and 12.3 g ai ha were applied 10 days apart beginning at matchhead square stage to cotton, Gossypium hirsutum L. in 1989 and 1990. Two cultivars, 'DES 119 and DPL 50', were evaluated by destructive sampling at 2 week intervals beginning at initial application of MC for effects on partitioning of phytosynthates to the various plant structures. Effects of MC on distribution and size of bolls at the fruiting sites was determined by plant mapping at maturity. The cultivars responded similarly to MC with a decrease in biomass accomplished by decreased plant height, leaf area, and stem and leaf weights. Weight of squares was greater 6 weeks after initial application of MC and lower at 8 weeks, reflecting the increase in earliness achieved by MC. This corresponded with a greater number of green bolls at early sampling dates and lower numbers at later dates in MC treated plants. The reproductive to vegetative ratio was 1.49, 1.72, and 1.76 for the 0, 2, and 4 oz. rates of MC. Seed index was increased by 2 and 4 oz. rates of MC. Overall lint yield, lint percent, and boll size were not affected by MC at either rate. MC increased the lint yield from bolls at position 1 at nodes 8 to 14 and at node 8 for position 2 in 1990. Thus, the yield was produced 3-6 days (equivalent to 1-2 nodes) earlier in MC treated plants. Boll size was increased at nodes 12 and 14 in 1989. MC as used in these experiments produced beneficial changes in plant maturity, plant canopy architecture, reproductive to vegetative ratio, and had neutral to positive effects on yield.



Reprinted from 1995 Proceedings Beltwide Cotton Conference pg. 576
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998