Effect of nitrogen application level on head milled rice in association with source-bank structure in mid-season hybrid rice | 施氮水平对杂交中稻整精米率的影响与组合间库源结构的关系

Chinese. 以26个籼型杂交中稻组合为材料，设施氮量、齐穗期疏花、剪叶处理，研究了施氮水平对杂交中稻整精米率的影响与组合间库源结构的关系。结果表明，两种施氮水平下整精米率的差值（低氮-高氮）分别与低氮和高氮下各组合相应的穗粒数呈极显著负相关关系。原因在于，中小穗型组合在低氮条件下的叶粒比已经较高，籽粒灌浆速率较快，导致籽粒充实度差而整精米率不高；当施氮水平提高后，叶粒比和灌浆速率进一步提高，籽粒容重进一步下降，因而整精米率下降。大穗型组合在低氮条件下，不足以维持籽粒正常灌浆，籽粒容重和整精米率下降；当提高施氮水平后，叶粒比有一定程度提高，库源矛盾有所缓解，籽粒容重也相应提高以致整精米率增加。预测出在4.5叶左右按26.64 cm×19.98 cm规格、每穴栽双株和本田施纯氮150 kg/hm2的栽培条件下，当群体平均着粒数≥194粒的杂交组合，整精米率比低氮水平有提高趋势。

English. In this paper, the relationship between the effects of nitrogen application level on head milled rice and source-sink structure at full panicle stage was investigated with 26 mid-season hybrid rice combinations. The results indicated there was a highly significant negative correlation between the head milled rice under 2 amounts of nitrogen application and in number of spikelets per panicle. The reason was that under low nitrogen application level, leaf-grain ratio, grain filling rate of the small-or middle-panicle type hybrid rice combinations was very high, so that the grain filling plumpness and the head milled rice was not high; while under the high level of nitrogen application, the leaf-grain ratio and grain filling rate was increased further, so that the grain unit weight and the head milled rice was decreased further. It suggests that the number of spikelets per panicle below 194 under seedlings were transplanted at 4.5-leaf stage, with a planting density of 19.98 cm×26.64 cm and 2 seedlings per hill. A total of 150 kg N per ha was applied during the entire growth period. This was an index for selecting variety of good quality rice in southern region of Sichuan Province, China.