Effects of Nitrogen and Silicon Nutrition on Rice Blast Occurrence under Intercropping with Different Type Varieties

A field experiment was carried out to investigate the effects of nitrogen and silicon nutritions on rice blast occurrence on a traditional glutinous rice variety Huangkenuo under intercropping with japonica variety chujing 26.Under the normal nitrogen supply(225 kg/hm~(2)N),the rice biomass aboveground and grain yield under intercropping increased by 15.8% and 20.8%;nitrogen content in culm and leaf reduced by 35.5% and 14.1%;silicon content in culm and leaf decreased by 13.9% and 8.8%,and severity index of leaf blast and panicle blast decreased by 10.0% and 27.7% in Huangkenuo,respectively.Nitrogen content in rice plant at higher nitrogen level(450 kg/hm~(2)N)was higher than that at normal nitrogen level.As a result,the severity indices of leaf blast and panicle blast in Huangkenuo were increased.There was a significant positive relationship between plant nitrogen content and rice blast incidence,the correlation coefficient ranged from 0.820~(**)to 0.968~(**).The plant silicon content with silicate application was higher than that without silicate application.Consequently,the severity index of panicle blast was decreased.There was a significant negative relationship between silicon content in culm and rice panicle blast occurrence,the correlation coefficient was from-0.969~(**) to-0.707~(*).The lower plant nitrogen content under intercropping could partially explain the rice blast control under diversified cultivation.