Effects Of Nitrogen Application On Yield, Dry Matter-accumulation And Remobilization, N-uptake And Utilization Of Double-cropping Rice

Two early rice combinations, Jingyou458,03you66and two late rice combinationsWufengyou T025and Shanyou10were used to study the effects of nitrogen applicationon yield and yield components, dry matter accumulation, distribution and transportation,photosynthetic characteristics, and nitrogen utilization efficiency, the results showed asfollows:(1) The yield on N treatment of early and late rice is larger than no N treatment.195kg/hm~2is the most appropriate amount of nitrogen on early and late rice, when Napplication rate is less than195kg/hm~2yield increased with the N application,whenapplied amount of N is higher than195kg/hm~2,output increase is not obvious. On yieldcomponents of early rice, effective panicle number and grain number increased beforethey are reduced when N application rate has a tendency to increase, with the increase ofN application rate thousand seed weight and seed setting rate has a tendency to reduce;On yield components of late rice, effective panicle number increased before they arereduced when N application rate has a tendency to increase, total grain number hasincreased with the increase of N application, seed setting rate has adecrease trend withthe increase of N application,the variation of thousand seed weight is not obvious.(2) The dry matter weight in early and late rice was higher than in no nitrogentreatment. Early rice had largest dry matter accumulation in the N application rate of225kg/hm~2; it has a parabola relationship between processing. Late rice had largest drymatter accumulation in the N application rate of195kg/hm~2; between processing it has aparabola relationshiptoo. The most beneficial to dry matter accumulation of Napplication rate on early rice is225kg/hm~2, when the most beneficial to dry matteraccumulation of N application rate on late rice is195kg/hm~2.(3) With the increase of N application stem dry matter ratio shows the tendency ofdecrease on elongation stage, heading stage, mature stage, the weight of leaves showed atrend of increase in the proportion. Spike dry matter ratio present a tendency of decreasewith the increase of N application on mature stage. With the increase of N applicationrate, stem and sheath output rate, stem and sheath conversion rate, apparent output of thestem and leaf material of early and late rice reduced.(4) The LAI of early rice and late rice are greatly influenced by nitrogen. There is anincreasing trend with increasing amount of nitrogen on LAI in fertility before, duringand post.The LAI is larger in N application than no N application. The SPAD and Totalnitrogen content in early rice and late rice showed a highly significant correlation, thetotal chlorophyll and SPAD in early rice and late rice showed a highly significantcorrelation. (5) The nitrogen content of plants shows degradation on elongation stage, headingstage and mature stage. With the increase in the amount of nitrogen the nitrogencontent of plants increased. There is an increasing trend with increasing amount ofnitrogen on leaf nitrogen content and stem nitrogen content at each growth stage. Thereis an increasing trend with increasing amount of nitrogen on the nitrogen content of theearly rice and late rice. It has a significant growth between N treatments and no Ntreatments.The N accumulation increased with the N application before heading stage.The proportion of N accumulation between heading stage and mature stage decreaseswith the increased of N treatments.(6)There is an increasing trend with increasing amount of N in stem N accumulation,leaf N accumulation and spike N accululatin on mature stage. The agronomic N useefficiency of early rice first increased and then decreased with increasing amount ofnitrogen. Absorption and utilization of N, nitrogen harvest efficiency, apparent Nrecovery efficiency and nitrogen partial factor productivity of early ricedecreased with increasing amount of nitrogen.Agronomic N use efficiency, N harvestefficiency and nitrogen partical factor productivity decreased with increasing amount ofN. Absorption and utilization of N and apparent N recovery efficiency first increased andthen decreased with increasing amount of nitrogen.