关键词: 杂交籼稻, 氮, 钾, 干物质, 产量

Abstract: The effects of combined application of nitrogen （N） and potassium （K） at different growth stage on yield formation were investigated with hybrid rice F you 498 as material. For N fertilizer treatments, the ratio of basal, tillering, spikelet-promoting and spikelet-preserving N were 5∶3∶1∶1 （N1）, 3∶3∶2∶2 （N2）, 3∶1∶3∶3 （N3） and N0 （no N fertilizer applied）; For K fertilizer treatments, the ratio of basal, tillering, spikelet-promoting and spikelet-preserving N were 10∶0∶0∶0 （K1）, 7:0:3:0 （K2）, 3∶0∶7∶0 （K3） and K0 （no K fertilizer applied）. The results showed that N1K1, N2K3 and N3K2 obtained the highest yield respectively with their corresponding N treatments, among which, N3K2 produced the maximum grains. For all N treatments, a larger proportion of K at later growth stage boosted the rate of productive tillers and effective panicle number, and for N2 and N3 treatments, total spikelets were also enhanced with more K applied later. A moderate reduction of K proportion at earlier stage was beneficial for dry matter accumulation at elongation stage. For post-anthesis dry matter accumulation and its ratio, K1 at N1 and N2, and K3 at N3 were the optimal respectively. Compared with K2 and K3, K1 got the most advantageous Pn value of flag leaf after anthesis at N1, though its leaf area index （LAI） of top three leaves and SPAD value were relatively poor at and after anthesis. For N2 and N3, K1 could slow down the reduction of SPAD and Pn value, but K2 and K3 possessed more advantageous LAI of top three leaves, and obtained higher yield ultimately. 

Key words: hybrid indica rice, nitrogen fertilizer, potassium, dry matter, yield