两优培九稻米垩白在江苏省不同纬度点的播期效应

通过在江苏4个稻作区（纬度范围为31.3°~34.7°N）设置5个播期处理，以两系杂交中籼稻两优培九为材料，研究其垩白变化特征。受播期和纬度的双重影响，两优培九稻米垩白率、垩白度的最大极差分别为54.0和13.0个百分点。垩白具明显的纬向性递变特征，种植的适宜区域在扬州至东海间，并以偏北地区（建湖、东海）较优，而在江苏的南北两端（昆山、沛县）要显著差于中间地带。在各稻作区稻米的垩白率（度）随播期推迟而降低，并且在江苏北部地区更易受播期调节。结实期的日平均温度与稻米垩白率、垩白度呈显著的线性正相关。因此，在高产条件下适当迟播栽培，是降低两优培九稻米垩白的优质生产途径。

Effect of Seeding Time on Chalkiness of Liangyoupeijiu in Jiangsu Rice Growing Areas at Different Latitudes

By using five seeding time treatments in four rice growing areas (the latitude ranges from 31.3°to 34.7°N) in Jiangsu Province, China, the characteristics of chalkiness of a two line mid season indica hybrid rice Liangyoupeijiu were studied. The chalkiness of Liangyoupeijiu was affected significantly by both seeding time and growing areas, the range of chalky grain rate and chalkiness degree were 54.0 and 13.0 percent point, respectively. The chalkiness of Liangyoupeijiu changed distinctly as the changing latitude of growing area, the area fitting for planting Liangyoupeijiu was between Yangzhou and Donghai, with the optimum region from Jianhu to Donghai; the chalky grain rate of Liangyoupeijiu planting in the extreme south and north areas in Jiangsu (Kunshan, Peixian) was higher than that in the middle area distinctly. The chalkiness in each growing area turned better when the seeding time delayed, especially in the north of Jiangsu Province. The daily average temperature at the productive stage had a significantly positive correlation with chalky grain rate and chalkiness degree. Therefore, it could be deduced that delaying seeding time properly would be an effective way to decrease chalkiness of Liangyoupeijiu under the condition of high yield cultivation in Jiangsu Province.