Effects of mepiquat chloride and foliar nutrition on growth, yield, and fiber quality in High-Density Planting System (HDPS)

Increased plant density promotes taller growth and greater vegetative development, intensifying competition among plants for resources and consequently affecting the balance between the vegetative and reproductive stages of the cotton plant. To ensure improved square development, boll development, boll retention, and seed cotton yield under dense planting condition, this research was conducted at the Cotton Research Station, Veppanthattai. The study aimed to evaluate the effects of plant growth regulators (PGR) and foliar nutrition on the growth, yield, and fibre quality of compact cotton varieties suitable for dense populations and mechanical harvesting. The results revealed that the application of mepiquat chloride (100ppm at 45 and 60 DAS), NAA (40ppm at 60 and 90 DAS), KNO3 (2% at 60 and 90 DAS), calcium borate (0.5% at 60 and 90 DAS), and a defoliant (Thidiazuron 240 g/L and Diuron 120 g/L at 200 ml/ha at the 60% boll bursting stage) achieved optimal growth attributes. These included plant height (98.7 cm), the number of functional leaves (07), leaf area index (3.9), seed cotton yield (2351 kg/ha), stalk yield (3286 kg/ha), lint yield (933 kg/ha), and harvest index (0.69), along with improvements in fiber quality parameters. In this study, potassium facilitated the efficient translocation of photosynthates from leaves to reproductive organs, contributing to enhanced biomass accumulation and yield.