Effect of different nitrogen doses on sucking pests and yield in Bt cotton under unprotected and protected conditions

Abstract

An experiment was conducted to know effect of different nitrogen doses (0, 120, 150, 180, 225, 280, 350, 440 kg ha­-1) on sucking pests and yield ­­in Jaadu BG-II cotton hybrid under protected and unprotected conditions at RARS, Lam, Guntur. The mean aphid population was increased from 14.12 to 42.54 and 9.67 to 26.20 per three leaves under unprotected and protected conditions respectively. Similarly, the mean leafhopper population was increased from 3.54 to 6.52 and 2.51 to 4.99 per three leaves under unprotected and protected conditions respectively. Significant positive correlations were observed with pest population. The highest seed cotton yield was obtained from plots applied with 150 kg N ha­-1 both under unprotected (1967 kg ha­-1) and protected (2272 kg ha­-1) conditions. However, thereafter decrease in yield was observed with increased nitrogen level.