Dynamic difference in main quality characters of rice during grain filling under different amounts of nitrogen fertilizer applied

Five keng rice varieties were used as test materials,and their dynamic change of rice quality and main quality difference between them at filling stage were analysed under applying nitrogen fertilizer(N10) and not applying nitrogen fertilizer(N0).The results showed that the difference in grain shape between them appeared at early filling stage instead of later filling stage.At the two nitrogen levels,the change of grain thickness for all the varieties had the same trend and the thickness obviously increased as grain filling.The daily increase rate was faster at early filling stage(from heading to the 25th day) than at the later stage,and also faster at N10 level than at N0 level.From heading to the 20th day,the amylose content of grain increased and then decreased.In the whole filling period the mean amylose content of grain was higher at N10 level than at N0 level,but there were differences between the varieties.At N0 level the colloidality increased as grain filling but at N10 level the colloidality decreased as grain filling.In the whole filling period the mean colloidality was higher at N0 level than at N10 level.At two nitrogen levels the correlation of percentage of brown rice was significantly positive with grain width,1000-grain weight and milled rice percentage,and significantly negative with protein content.At N0 level there were significant positive correlations of gelatinizing temperature with grain width and milled rice percentage,and significant negative correlations of crude protein with grain width,1000-grain weight,brown rice percentage and milled rice percentage.At N10 level there was a significant negative correlation between gelatinizing temperature and protein content and also significant negative correlations of protein content with grain width, brown rice percentage and milled rice percentage.