Evaluation of BT Cotton Genotypes and Nutrient Management to Control Leaf Reddening

Abstract

Two field experiments on Assessing leaf reddening malady in Bt cotton genotypes newlineand Studies on nutrient management to overcome leaf reddening in Bt cotton were newlineconducted on vertisols at MARS, University of Agricultural Sciences, Dharwad during kharif newline2007 and 2008. Mean of two years data from the first experiment indicated that cv. Neeraja- newlineBG-II-Bt recorded significantly higher seed cotton yield (2483 kg/ha) and net monetary return newline(Rs. 28,832/ha) compared to other cultivars (1131 to 2071 kg/ha and Rs. 1950 to 20,669, newlinerespectively). At 120 DAS, cv. Neeraja-Non-Bt recorded significantly higher total chlorophyll newline(1.66 mg/g fresh weight) and lower anthocyanin (0.137 mg/g fresh weight) while cv. Sahana- newlineNon-Bt recorded significantly higher red leaf index (2.12). Seed cotton yield was positively newlinecorrelated with total chlorophyll (r=0.34) while negative correlation with anthocyanin (r=-0.09) newlineand red leaf index (r=-0.03) was observed among the genotypes studied at 120 DAS. Results newlinefrom the second experiment revealed that foliar application of KNO3 at 2% produced newlinesignificantly higher seed cotton yield (2543 kg/ha) and net monetary return newline(Rs. 27807/ha) compared to other treatments (1383 to 2522 kg/ha and Rs. -145985 to 27722, newlinerespectively). At 120 DAS, significantly increased total chlorophyll, decreased anthocyanin newlineand lower red leaf index were recorded with soil and foliar application of MgSO4 at 25 kg/ha newlineand 1%, respectively (1.77, 0.08 mg/g fresh weight and 1.05, respectively) which were on par newlinewith treatments of KNO3 at 2% foliar application (1.70,0.10 mg/g fresh weight and 1.05, newlinerespectively) and soil application of MgSO4 at 25 kg/ha (1.70, 0.11 mg/g fresh weight and .05, newlinerespectively). Significant positive correlation between seed cotton yield and total chlorophyll newline(r=0.95) was observed while negative correlation with anthocyanin (r=-0.86) and red leaf index newline(r=-0.97) was noted at 120 DAS. Polyethylene mulching in between two Bt cotton rows did not newlineinfluence significantly in overcoming leaf reddening.