Abstract

Field studies were conducted to determine the effect of different defoliants i. e. Dropp ultra® and Ethrel (ethefon), their rates and time of application (140 and 150 DAS) to influence earliness and yield in three cotton cultivars. MRC 7361 BGII (3171.8 kg/ha) and MRC 7017 BGII (3083.3 kg/ha) gave significantly higher yield as compared to F 1861 (2454.9 kg/ha) due to better boll retention, boll weight and sympods. Dropp ultra® @ 200 ml/ha recorded significantly highest yield (3111.6 kg/ha) followed by Ethrel @ 2000 ppm (2948.3 kg/ha) and control (2878.9 kg/ha), while statistically least yield (2674.5 kg/ha) was observed with Dropp ultra® @ 225 ml/ha. Defoliants applied at 150 days after sowing (DAS) resulted in significantly higher yield (3017.7 kg/ha) as compared to early application at 140 DAS (2789.0 kg/ha) owing to significantly improved boll retention and better boll weight. Data indicated that Dropp ultra® @ 200 ml/ha had potential to promote crop earliness, better boll retention by keeping vegetative and reproductive growth in harmony to enhance seed cotton yield.