Response of cotton, Gossipium hirsutum L to plant growth regulators

Field studies were conducted in Rajasthan with plant growth regulators viz GA, NAA, Cycocel, ethephon and TIBA at 100 ppm and benzyladenine at 0.5 ppm to determine their effects on yield and yield attributes of cotton cultivar RST-9. The chemicals were foliar sprayed at square formation stage and 20 days after first spray. Results showed that the foliar application of NAA at 100 ppm brought about significantly higher mean seed cotton, cotton seed and lint yield by 57.3, 53.3 and 67.6 per cent respectively over water spray which resulted due to better, balanced plant growth and greater partitioning of assimilates towards yield formation as evidenced by higher number of flowers plant⁻¹ (76.9), bolls plant⁻¹ (49.3), mature bolls plant⁻¹ (24.5), per cent boll setting (49.8), seed cotton weight boll⁻¹ (104.3 g) and cotton weight boll⁻¹ (4.23 g). This treatment was closely followed by Cycocel, ethephon at 100 ppm and benzyladenine 0.5 ppm.