Effects of Carbon and Nitrogen Fertilisers on Rice Quality of the OsNRT2.3b-Overexpressing Line

Excessive nitrogen fertiliser use reduces nitrogen use efficiency and causes significant damage to the environment. Carbon fertilisers have the advantage of improving soil fertility; however, the effects of carbon and nitrogen fertilisers on rice yield and quality are not clear. In this study, the nitrogen-efficient line (OsNRT2.3b-overexpressing [O8]) and wild type (WT) were treated with different levels of nitrogen and carbon fertilisers under field conditions to study the effects of different fertilisation treatments on rice quality. The results showed that the appearance, nutrition, and taste qualities of O8 were generally high compared with WT under various fertilisation treatment conditions in 2019 and 2020. Compared with 90 kg/ha and 270 kg/ha nitrogen fertiliser, a single application of 90 kg/ha and 270 kg/ha carbon fertiliser significantly reduced the protein content of O8 by approximately 37.08% and 35.50% in 2019 and 2020, respectively, compared with WT, and improved the eating quality of O8 and WT. However, the replacement of nitrogen fertiliser with 20% carbon fertiliser did not improve the eating quality of O8 and WT compared with a single application of nitrogen fertiliser. This study identifies a high-quality gene, OsNRT2.3b, for breeding high-quality rice and provides a theoretical basis for obtaining high-quality rice and molecular breeding.