Effects of rice grain protein QTL, TGP12, on grain composition, yield components, and eating quality with different nitrogen applications
2021
Kashiwagi, Takayuki
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.
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