始穗期施氮钾肥对两系稻N31S／P40结实性的影响

INFLUENCES OF NITROGEN AND POTASSIUM TOP-DRESSED AT INnIALHEADINGSTAGE ON SPIKELET FERTILITY OF TWO-LINE HYBRID N31S/P40

盆栽试验表明，适当减少生产前期的氮或氮钾肥施用量对两系稻Ｎ３１Ｓ／Ｐ４０有效穗数和每穗粒数影响很小，但将总肥量１／３左右的氮或氮钾在始穗期施用，明显促进籽粒在灌浆初期的淀粉积累，改善籽粒的结实性、结实率、谷产量和收获指数明显提高。增加始穗期氮钾施用比例比单纯增加施氮比例效果更好。

In this experiment,nitrogen or nitmgen and ptassium accounting for one third total fer-tilization amount was topdressed to the pot grown two-line ybrdrid rice N31/P40 at the ini-tial heading stage.Compared with the control,to which the fertilizers were all applied beforetransplanting,the number of effective panicles and total spikelets per panicle were not influ-enced by reducing one third nitrogen or nitrogen and potassium at the early growth stage.However,top-dressing at initial heading stage could play a very important role in stimulatingstarch accumulation of kemels at the early stage of filling,improving the spikelet fertility,particularly improving the spikelet fertility of the kernels on mid-and low-branches of thepanicle.There were significant effects on increasing the filled grain rate,grain yield and har-vest index.But,the effect of top-dressing nitrogen and potassium at initial heading stagewas better than that of top-dressing nitrogen alone.