S.V. Nehete, Swati S. Gurve, Ram K. Wargantiwar, Atul D. Gonde and P.K. Lokhande
Abstract
Biochemical studies were carried out against eight Bt cotton hybrids Bunny, Dhuv, Monsoon, NHH-44, Rasi-2, Dyna, Mallika and Tulasi at the MPKV Rahuri, revealed the total polyphenol content in leaves of Bt cotton hybrids at 30 DAS maximum of 6.05 mg g-1 fr.wt. being present in Dyna. At 60 DAS maximum of 7.91 mg g-1 fr.wt. being present in NHH-44 and 90 DAS maximum of 8.41 mg g-1 fr.wt. in Tulasi. The tannin content in leaves at 30 DAS maximum of 3.98 mg g-1 fr.wt. being present in Dhruv at 60 DAS maximum of 8.74 mg g-1 fr.wt. being present in Monsoon and at 90 DAS the maximum of 8.35mg g-1 fr.wt. being present in Monsoon.The chitinase activity in leaves of Bt cotton hybrids the maximum of 4.75 mg Nacetylglucosamine released g-1 fr.wt. hr -1 being present in Dyna at 60 DAS the maximum of 4.98 mg g-1 fr.wt. hr-1 being present in Rasi-2 and at 90 DAS the maximum of 6.65 mg g-1 fr.wt. hr-1 being present in Dhruv. The peroxidase activity the maximum of 2.24 units g-1 fr. wt. being present Dhruv at 60 DAS the maximum of 2.65 units g-1 fr. wt. being present in Dyna and at 90 DAS peroxidase activity ranged from 2.13 to 5.00 units g-1 fr. wt.. The maximum of 5.00 units g-1 fr. wt. being present in Monsoon and the minimum of 2.04 units g-1 fr. wt. in Tulasi. The polyphenol oxidase activity in leaves of eight Bt cotton hybrids ranged from 0.85 to 2.22 units g-1 fr. wt. at 30 DAS. The maximum of 2.22 units g-1 fr. wt. being present Dyna and the minimum of 0.85 units g-1 fr. wt. Monsoon and at 60 DAS ranged from 1.03 to 2.56 units g-1 fr. wt. The maximum of 2.56 units g-1 fr. wt. being present in Dyna and the minimum of 1.03 units g-1 fr. wt. in Monsoon. At 90 DAS ranged from 1.03 to 3.22 units g-1 fr. wt. The maximum of 3.22 units g-1 fr. wt. being present in Dyna and the minimum of 1.03 units g-1 fr. wt. in Dhruv is moderately resistant against the sucking pest infestation and higher biochemical constituents at different growth stage.