Individual Experiments to Evaluate the Effects of Plant Population and Planting Date, Cultivar and Plant Growth Regulator Application, and Herbicide and Plant Growth Regulator Application on Cotton (Gossypium hirsutum L.) Growth and Development, Yield, and Fiber Quality

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Virginia Tech

Cotton (Gossypium hirsutum L.) growth and development, lint yield, and fiber quality are influenced by many management decisions. Three field experiments examining the interaction of plant population and planting date, and cultivar or herbicide and plant growth regulator application on these parameters were conducted in Virginia during 2005 and 2006 and in North Carolina, South Carolina, and Louisiana during specific years.

Experiment I: Plant Population and Planting Date

Lint yields were highest with populations of 8.9 and 12.8 plants m¯² compared to 5.3 plants m¯² in Virginia and North Carolina, while in Louisiana the highest yields resulted from populations of 5.8 and 9.5 plants m¯² compared to 17.1 plants m¯². Earlier planted (1 May) cotton produced higher yields relative to later planted (21 May) cotton in Louisiana, while yield was not influenced by planting date in Virginia and North Carolina. The impact of plant population and planting date on cotton appeared to be influenced significantly by heat unit accumulation.

Experiment II: Cultivar and Mepiquat Pentaborate Application

Mepiquat pentaborate (MPB) application consistently decreased plant height, HNR, and enhanced maturity for all cultivars, compared to untreated cotton. A trend of decreasing yield with increasing MPB application in Virginia was observed. These data suggests that cotton response to MPB application is influenced by cultivar maturity or fruiting interval.

Experiment III: Trifloxysulfuron-sodium and Mepiquat Chloride Application

Trifloxysulfuron-sodium (TFS) did not influence vegetative growth, maturity, or yield in comparison to untreated cotton. Mepiquat chloride (MC) application reduced vegetative growth and enhanced maturity in most years. The results of this experiment demonstrate that TFS application does not have the same effects on plant growth as MC application.

mepiquat pentaborate, cultivar, plant population, cotton (Gossypium hirsutum L.), planting date, trifloxysulfuron-sodium, mepiquat chloride