Aims: Relationships between areas of monopodial and sympodial leaves reported in the literature suggest a consistent size gradient among leaves along the sympodial branches of cotton plants. The objective of this study is to assess how well a non-destructive procedure based on these relationships can estimate leaf area of cotton plants. Study Design: Randomized complete block with 6 replications.

Greenhouse and laboratory experiments were carried out with the purpose of studying effects of the plant growth regulators (PGR) mepiquat chloride (MC) and cyclanilide (CY) as seed treatments on the early growth of cotton. Seeds of cultivars NuOpal, Fibermax-993, Fibermax-910, FMT-701 and FMT-523 were treated with MC (4.50 g kg-1 seed), MC+CY (1.60+0.40 g kg-1 seed) and MC+CY (4.50+1.12 g kg-1 seed). In laboratory, seed storage periods of 4 and 50 days were also tested. MC+CY treatments decreased plant height by approximately 50%, whereas MC decreased plant height about 30 to 40%. The greatest and lowest rates of MC+CY decreased the height of cotyledon node by 33 and 12% compared to MC treatment, respectively. MC and control treatments did not differ from each other on radicle length (RaL), taproot length (RL) and secondary root initiation depth (SRI). The greatest MC+CY rate resulted in the greatest SRI values, increased RL by 7% and R a L by 29% compared to the control. Seed storage period did not affect consistently the performance of treated seeds. Short-cycle cultivars have a greater sensitivity to seed treatment with PGRs, whereas CY synergizes with MC to reduce shoot growth and inhibits emission of secondary roots.

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