Cooking and eating quality of rice as affected by nitrogen fertilizers and alternate wetting and moderate drying irrigation at panicle stage

The grain filling is the key period for quality formation in rice, which is greatly influenced by nitrogen (N) fertilizer and irrigation management. This study aimed to investigate effects of different N fertilizer rates and irrigation regimes at panicle stage on rice cooking and eating quality. A superior taste japonica variety Nanjing 9108 (NJ9108) was planted in the field. Under the condition of 150 kg N hm−2 base-tiller fertilizer, four panicle N fertilizer rates (0, 70, 140, and 210 kg hm−2) were applied, and two irrigation regimes, viz. conventional irrigation (CI) and alternate wetting and moderate drying irrigation (AWMD), were imposed during grain filling. The results showed that panicle N fertilizer rates and irrigation regimes interacted partially to regulate cooking and eating quality of rice. The lipid content in milled rice and the quality were reduced with increasing panicle N fertilizer rate, while the protein content was changed reversely. Compared to CI, AWMD regime increased lipid content and improved the quality as well as grain yield at four panicle N fertilizer rates. In two study years, the protein content was lower in the AWMD than in the CI when panicle N fertilizer rates were greater than 106.7 kg hm−2 and 131.0 kg hm−2, respectively. Correlation analysis indicated that lower protein content and higher lipid content were beneficial to the improvement of rice cooking and eating quality. The results also suggested that NJ9108 can obtain a win-win goal of superior quality and high yield when panicle N fertilizer rate is 106.7–131.0 kg hm−2 and the AWMD is adopted during grain filling. Such a study can provide references for the cultivation of superior taste japonica rice.