The Effects Of Planting Density And Fertilizer On Yield And Rice Quality Of Direct Seeding Rice And Analysis Of Reason

The field experiments were conducted in the breeding center of Shanghai in rice growth seasons of 2000 and 2001. Wuyunjing8 (Japonica) and Hanyouxiangqing (Japonica hybrid) used in local rice production were drill-planted in field. The experimental designed factors mainly concerned planting density, the quantum and data of nitrogen fertilizing and the ratio of nitrogen and phosphate and Potassium. The effects of those designed factors on yield, dry matter production, harvest index, rice quality and nutrient absorbing, were investigated in an attempt to elucidate the developmental characteristics of drill-planted rice and to establish the model of high-yield planting. Main results were described as follow.(l)Under the same nitrogen fertilizing, increased planting density of Wuyunjing8 significantly enhanced dry matter accumulation from the critical tillering stage to elongation and increased panicles per area, but markedly decreased biomass production and nitrogen absorbing from elongation to maturity, spikelets per ear and harvest index. 120 single stems per m2 of density is suitable for yield, but increased density led to a inferior performance of milling quality and appearance quality, and increased the content of amylose and the length of gel and decreased the content of coarse protein.(2)As applying the same planting density of Wuyunjing8, increased nitrogen could significantly increased spikelets per ear. biomass accumulation, harvest index, yield and nitrogen absorbing at different growth stages. With increasing nitrogen, appearance quality and coarse protein also improved, but increased chalkiness and thus led to the decrease of transparency.(3)Under applying the same nitrogen for Wuyunjing8 increased fertilizing of phosphate and potassium significantly increased ears per area, spikelets per ear, biomass accumulation, harvest index and yield, and enhanced the absorbing of nitrogen, phosphate and potassium. Based on quality performance, applying of phosphate and potassium decreased amylose content and increased the content of coarse protein and the length of gel, thus rice quality was improved.(4)Based on yield performance, applying high nitrogen associated with low density was suitable for wuyunjing8 while applying middle nitrogen associated with low density for HanyouxiangQing.(5)Under applying the same nitrogen and planting density, decreased nitrogen fertilizing of early and middle stages and increased ear-fertilizing, could decreased dry matter accumulation and nitrogen absorbing at early and middle stages, but significantly increased spikelets per ear and yield, dry matter accumulation at the later growth stage and nitrogen absorption. Mill quality of Hanyouxiangqing was improved, but increased the content of coarse protein, and led to an inferior performance of appearance quality.(6)The basic characteristics of yield formation of drill-planted rice appeared as more spikelets per ear, larger grain weight, but ears per area and filled grain percentage varied with cultivars. The total accumulation of dry matter is larger, the distribution of dry matter showed as smaller from transplanting to elongation and larger from elongation to maturity, thus led to a higher harvest index. Nutrient absorbing mainly distributed at the later growth stage, but the total absorbing was stable.(7)As long as the yield was concerned, increasing yield of Wuyunjing8 mainly depended on increasing spikelets per panicle and ears per area.(8)Increasing dry matter accumulation from elongation to heading, could significantly increased dry matter production after heading and spikelets per area, thus increased total bimass and harvest index that led to the increase of yield in drill-planted rice.(9)Increasing nutrient absorbing of drill-planted rice from elongation, was an important approach to increase harvest index and yield, largely due to increase spikelets per area and dry matter accumulation from heading.