Effects Of Density And Nutrient Management On N Accumulation And N Efficiency Of Direct-seeded Rice In Cold Area

A plot experiment with rice cultivar Longjing31was conducted to study the difference in N accumulation and yield of direct-seeded under different density in2012in cold area. Results showed that N content in direct-seeded rice leaf of M1at heading stages was12.4%and14.4%higher than that of M2and M3direct-seeded rice (P<0.05), and the photosynthetic production of direct-seeded rice leaf was significantly increased. The vegetative organs of M1have sufficient nutrients so that N accumulation in rice grains at maturity stage was13.8%and19.3%higher than rice grains of M2and M3(P<0.05). N assimilation of Ml after heading was39.8%(P<0.01) and81.4%(P<0.01) higher than that of M2and M3, contribution of N assimilation to grain of M1was22.7%(P<0.05) and50.7%(P<0.01) higher than that of M2and M3, partial factor productivity of applied N of M1was8.3%(P<0.05) and14.9%(P<0.05) higher than that of M2and M3, and the number of grains per panicle was significantly increased on the basis of the optimum panicle number per unit area. The1000-grain weight and filled grain rate were increased, and the yield of M1was8.3%(P<0.05) and15.0%(P<0.05) higher than that of M2and M3.,A micro-plot experiment with rice cultivar Longqingdao2was conducted to study the difference in N accumulation and yield of conventional fertilization (F1) and optimum fertilization (F2) rice in2013. Results showed that N content in direct-seeded rice leaf of P1F2at heading and filling stages were11.1%(P<0.05) and15.6%(P<0.05) higher than that of P1F1, and the photosynthetic production of direct-seeded rice leaf was significantly increased so that extending photosynthetic time. The vegetative organs of P1F2have sufficient nutrients so that N accumulation in rice grains at maturity stage was18.1%(P<0.05) higher than rice grains of P1F1, that of P2F2was18.0%(P<0.05) higher than P2F1. N assimilation and contribution of N assimilation to grain after heading of P1F2was38.3%(P<0.01) and18.2%(P<0.05) higher than that of P1F1, the yield of P1F2was7.2%(P<0.05) higher than that of P1F1. Comparing with transplanting rice, the yield of direct-seeded rice was increased by increasing the number grains per panicle, and the yields of direct-seeded rice and transplanting rice have no significant difference.A field experiment with rice cultivar Longyou5was conducted to study the difference in N accumulation and yield of direct-seeded and transplanting rice in cold area. Results showed that N content in direct-seeded rice leaf at heading and filling stages was10.2%and10.0%(P<0.05) higher than that of transplanted rice(P<0.05), and the photosynthetic production of direct-seeded rice leaf was significantly increased. The vegetative organs of direct-seeded rice have sufficient nutrients so that N accumulation in rice grains at maturity stage was16.1%higher than transplanted rice grains (P<0.05). N assimilation after heading of direct-seeded rice was104.7%(P<0.01) higher than transplanting rice, partial factor productivith of applied N of direct-seeded rice was37.2%higher than that of transplanted rice (P<0.01), and the number of grains per panicle and1000-grain weight was significantly increased on the basis of the optimum panicle number per unit area. The filled grain rate were increased, and the yield of direct-seeded rice was8.1%higher than transplanted rice (P<0.05).