[Effect of nitrogen fertilization and square loss on cotton aphid population, cotton leafhopper population and cotton yield].

The study on the effects of nitrogen fertilization(0～450 kg·hm -2 )and square loss(0～12·plant -1 )on cotton aphid population,cotton leafhopper population and cotton yield showed that there were no significant differences in cotton aphid population,cotton leafhopper population,and numbers of effective bolls between transgenic Bt cotton and non-transgenic cotton.Cotton aphid populations on the two cottons were significantly influenced by nitrogen fertilization and by the interaction of nitrogen fertilization and square loss,while leafhopper populations were not significantly influenced by them.Nitrogen fertilization at squaring and flowering stage was one of important factors affecting cotton yield.There was a positive correlation between the application rate of nitrogen fertilizer and cotton yield,but a negative correlation between the number of lost square per plant and the yield of the two cottons.