水稻粒重对氮素反应的基因型差异及其类型

以国内外114个水稻基因型的大田试验，研究了0、低、中、高4种氮素水平条件下粒重的变化规律，探讨了水稻粒重对氮素反应的基因型差异及其类型。结果表明：(1)早、中、晚稻在4种氮素水平下粒重均存在极显著的基因型差异。在不施氮条件下，早、中、晚稻平均粒重分别为23.95 g、25.34 g和25.37 g，基因型间的变异系数分别为5.57

Genotypic Difference and the Classification in Response of Grain Weight to Nitrogen in Rice

Grain weight is one of the important factors for yield. In high-yield cultivation, grain weight has become the principal focus for enhancing grain yield. However, limited by test conditions and materials, whether there are genotypic differences in grain weight is controversial up to now. The change of grain weight under different nitrogen levels (zero, low, medium and high) in the field was studied using 114 rice genotypes from domestic and abroad. Genotypic difference in response of grain weight to nitrogen was discussed and their types were classified. The results were as follows:(1) For early-season rice, mid-season rice and late-season rice, there were significant genotypic differences in 1 000-grain weight under four nitrogen levels. Under zero nitrogen, the average 1 000-grain weights were 23.95 g, 25.24 g and 25.37 g, respectively, and the coefficients of variation among genotypes were 5.57, 13.75 and 8.99, respectively. Under nitrogen level of 150 kg/ha, the average 1 000-grain weight were 23.47 g, 24.28 g and 23.42 g, respectively, and the coefficient of variation among genotypes were 4.54%, 13.24% and 9.96%, respectively. Under nitrogen level of 225 kg/ha, the average 1 000-grain weight were 23.24 g, 23.44 g and 23.05 g, respectively, and the coefficient of variation among genotypes were 4.31%, 13.04% and 10.55%, respectively. Under nitrogen level of 300 kg/ha, the average grain weights were 23.21 g, 23.20 g and 22.75 g, respectively, and the coefficient of variation among genotypes were 4.29%, 13.67% and 9.82%, respectively. (2) There were significant genotypic differences in response of grain weight to nitrogen, with 1 000-grain weight under different nitrogen levels from 0.16 g to 6.67 g and coefficient of variation from 0.35%-12.74%. (3) The change trends of grain weight in different rice genotypes with the increase of nitrogen level could be classified into four types that were named as normal parabola, reversed parabola, linear fall and leap, respectively. Based on the range and variation coefficient of grain weight under different nitrogen levels, rice genotypes could be classified into five types that were named as higher insensitive type, insensitive type, intermediate type, sensitive type and higher sensitive type.