Environmental and genetic factors control the grain protein content of rice. Among the environmental factors, the application of nitrogen (N) fertilizer especially affects grain protein content. It is important to clarify the interactions between genetic factors and N applications for breeding programs to improve rice protein. This study demonstrated the effects of QTL for grain protein content, TGP12, on grain composition, yield components, and eating quality of cooked rice under different N applications, including high basal application and top-dressing conditions. On the conventional and high basal application, the chromosomal segment substitution line with TGP12 (CSSL-TGP12) showed different grain protein contents, compared to Koshihikari. Yield per plant depended on environmental factors, including N application and year in which the experiment was conducted. Eating quality traits were mainly affected by experimental year. High N application rate with top-dressing at heading restrained the effect of TGP12 on grain protein contents, while it contributed to improve yield traits. Genotype and experimental year altered eating quality traits under top-dressing condition. There were three interactions between TGP12 and top-dressing on grain protein contents, leaf senescence at the fully ripe stage, and amylose content. These results suggest that the combination of TGP12 and high basal application would contribute to high grain yield and low protein content in grains but top-dressing at heading could decline the effect of TGP12 on grain composition. Furthermore, the interaction between TGP12 and top-dressing would alter N application effects on leaf senescence at the fully ripe stage and amylose content in grains.

环境和遗传因素控制着水稻的谷物蛋白质含量。在环境因素中，氮（N）肥的施用尤其影响谷物蛋白质含量。重要的是要阐明遗传因素与氮素在育种计划中的应用之间的相互作用，以改善水稻蛋白。这项研究表明QTL的籽粒的蛋白质含量，其影响TGP12，对谷物组合物，产量构成，并在不同的N个应用，包括高的基础应用和追肥条件米饭的食用品质。在常规和高基础应用中，用TGP12（CSSL- TGP12）与越光相比，谷物蛋白质含量有所不同。每株植物的产量取决于环境因素，包括施氮量和进行实验的年份。饮食质量特征主要受实验年份的影响。抽穗期追施氮肥的比例高，抑制了TGP12对籽粒蛋白质含量的影响，但有助于提高产量。基因型和实验年份改变了追肥条件下的饮食质量特征。TGP12和追肥之间在谷物蛋白质含量，完全成熟阶段的叶片衰老和直链淀粉含量之间存在三种相互作用。这些结果表明，TGP12的组合较高的基础施用量将有助于谷物的高产和低蛋白含量，但抽穗期追肥可能会降低TGP12对谷物组成的影响。此外，TGP12和追肥之间的相互作用将改变氮素对完全成熟期叶片衰老和籽粒中直链淀粉含量的影响。