Effects of nitrogen application rate on yield and grain quality of mechanical-transplanted hybrid Japonica rice Xuyou403

Effects of the different nitrogen application rates on yield and quality of mechanical-transplanted hybrid rice were studied under the yearly rice-wheat crop system in the Lixia River area. The cultivar is Xuyou403, a mid-season hybrid japonica rice cultivar. With the increase of nitrogen application rate, the harvested panicles per plant, number of grains per panicle, and the grain yield are increased first and then decreased; the 225 kg/ha nitrogen application rate is rate for the highest production. The grain filling rate and 1000-grain weight appear to be decreased along with the increase of nitrogen application rate. The nitrogen application rate mainly affected the chalkiness degree and the chalkiness rate, then setback, the other rice qualities were less effected. The milled rice qualities, the surface area, and section area are at their best values at the 225 kg/ha nitrogen application rate, the same as the grain yield, while the other grain qualities trended to be bad with the increase of nitrogen application．Considering the grain yield and quality together, the 225kg/ha of nitrogen fertilizer rate is suitable for rice production.