Effect of mepiquat chloride on growth parameters and yield of Bt cotton (Gossypium hirsutum) under high-density planting system

A field experiment was conducted during the rainy (kharif) seasons of 2018 and 2019 at Sardarkrushinagar, Gujarat, to study the productivity enhancement of Bt cotton (Gossypium hirsutum) grown under high-density planting system using mepiquat chloride. The experiment was laid out in split-plot design, with planting density in main plots and mepiquat chloride treatments in subplots. Pooled data of 2 years revealed that, Bt cotton grown with lower plant density (37,037 plants/ha) recorded significantly higher sympodial branches/plant, sympodial length at 50% height, number of bolls/plant and average boll weight, while high-plant density (74,074 plants/ha) resulted in the maximum seed-cotton (3,544 kg/ha) and stalk yield (3,740 kg/ha) as well as net realization (79.1 × 10³/ha). The magnitude of increase in seed-cotton yield owing to higher plant density over lower plant density was 68.53%, on pooled basis. Application of 3 sprays of mepiquat chloride @ 0.4 ml/litre (one each at 45, 60 and 75 days after sowing) resulted in the least growth parameters, viz. plant height, dry-matter accumulation, crop-growth rate, relative growth rate and stalk yield with a highest yield attributes, viz. sympodial branches/plant, sympodial length at 50% height, bolls/plant, average boll weight, seed-cotton yield (3,186 kg/ha) and net realization (66.8 × 10³/ha). Three sprays of mepiquat chloride @ 0.4 ml/l at 45, 60 and 75 days after sowing resulted in 28.8% higher seedcotton yield than control treatment in pooled mean.