Effect of N level on rice yield, nitrogen accumulation and rice blast occurrence under rice intercropping system

Abstract: Plant N nutrition plays an important role on plant metabolisms and crop diseases resistance. Intercropping can increase grain yields greatly and provide an ecological approach to disease control. Field trails of using two rice varieties with different resistance to rice blast, Huangkenuo (HKN) and Hexi-41(HX41), was carried out to investigate the effect of nitrogen fertilizer rate on rice yield, nitrogen accumulation and rice blast occurrence under rice mono-cropping and intercropping. The results showed that high nitrogen rate application (N 300 kg/ha) reduced the biomass, yield and increased the incidence and severity of rice blast, significantly in monocropping Huangkenuo. But under rice Huangkenuo intercropped with Hexi 41, high nitrogen rate showed no significant effect on the yield, and the increase of rice blast was not so significant as the mono-cropping rice. Under low nitrogen level, Hexi-41 and Huangkenuo intercropping increased the biomass, yield, and decreased the occurrence and severity of rice blast. The increase of N accumulation with high N rate in intercropping rice was much higher than that in mono-cropping. The inter-planting advantage, that the effect of increasing yield and LER and reducing the rice blast incidence and severity was much more significant at high N level