Impact of Growth Retardant and Defoliant on Morpho-physiological Traits and Yield Improvement in Cotton

In cotton, mechanized harvesting has gained popularity in recent years due to labor-intensive process and shortage of labor. Moreover, mechanized harvesting of cotton depends on plant morphological characters like plant height, internodal length and synchronized boll maturity and opening etc. Mechanized harvesting enhancing the harvesting efficiency of cotton which is achieved by the use of some chemicals to attain good lint yield and fibre quality. With this background, the field experiment was conducted to study the impact of growth retardant and defoliant on morpho-physiological traits and yield improvement in cotton (CO 17) during 2021-2022 by following randomized block design with four treatments and five replications. The current study revealed that spraying of 0.015% mepiquat chloride (MC) at square formation and boll development stage significantly reduced the leaf area, plant height, total dry weight and boll number when compared to control. However, chlorophyll content and normalized difference vegetation index (NDVI) were recorded higher in 0.015% mepiquat chloride (MC) applied treatments than control. Moreover, spraying of mepiquat chloride (0.015%) at square formation and boll development stage followed by spraying of 0.9% sodium chlorate (SC) at 60% boll bursting stage significantly increased the seed cotton yield compared to other treatments and recorded maximum seed cotton yield of 25.22% compared to control. Results clearly indicate that application of MC followed by SC could be a better practice for canopy management in cotton, resulting in improved efficiency of mechanical harvesting and good lint yield and fibre quality.