Quantifying the impact of environmental conditions on the effectiveness of mepiquat chloride in modulating canopy architecture, yield, and quality of drought-stressed cotton (Gossypium hirsutum L.)

Abstract

This study, conducted in the semi-arid region of Turkey, during the 2022/23 cropping season, employed a split-split-plot design with three replications to evaluate the impact of Mepiquat chloride (MC) on the growth, yield, and quality of newly developed cotton varieties. The main plot comprised two cotton varieties, while the sub-plots represented two MC application timings and the sub-sub plots included four MC dosages. Although statistical analysis revealed that treatment differences were generally not significant for most parameters, notable trends were identified. In 2022, MC treatments delayed cotton development, whereas in 2023, they improved fiber quality. The highest fiber percentage was recorded under the control treatment in 2023, while in 2022, it peaked at a dosage of 400 mL•ha?¹. Among the varieties, Selin showed the highest fiber percentage when MC was applied during the bolling stage. Additionally, the shoot-root ratio reached its maximum at 400 mL•ha?¹ during harvest in 2022 and at 0 mL•ha?¹ during the reproductive stage in 2023. These results indicate that the effectiveness of MC in promoting physiological traits and alleviating drought stress appeared to be closely associated to weather variability, underscoring the necessity for site-specific management strategies to achieve optimal outcomes.