Grain quality of different type of rice varieties under different environments and cultivation techniques

Enhancing quality has become a pivotal goal in rice production. However, the effects of temperature and light environments on rice quality across different varieties were unclear. In this study, nine widely promoted rice varieties were selected as materials and classified into five types: inbred indica rice, inbred japonica rice, indica hybrid rice, japonica hybrid rice and indica / japonica hybrid rice. The study investigated the changes in temperature and light environments and rice quality in them under different environments. Additionally, the regulation of alternate wetting and moderate soil drying (AWMD) irrigation on them were examined. The results indicated that: (1) under different environments, inbred japonica rice exhibited higher head milled rice rate, breakdown and taste value, as well as lower length-to-width ratio, amylose content, protein content and setback. (2) The minimum and maximum temperatures were negatively correlated with head milled rice rate and were positively correlated with peak viscosity and hot viscosity. Notably, both minimum and maximum temperatures during the middle-early and late grain filling stages showed significant positive correlations with viscosity. (3) Compared with the continuously flooded regime, canopy temperatures in Nangeng 9108, Changyou 5 and Yongyou 2640 were reduced by 5.30%, 3.42% and 2.90% under the AWMD regime, respectively. Moreover, AWMD significantly increased head milled rice rate while decreasing peak viscosity, hot viscosity and viscosity across different rice types, with a more pronounced effect observed in Nangeng 9108. This study could provide theoretical insights for temperature and light environments and rice quality and offers novel perspectives for improving rice quality. • Under different temperature and light environments, japonica rice had higher quality. • Optimizing temperatures improved head milled rice rate and viscosity characteristics. • AWMD reduced canopy temperature and improved viscosity characteristics. • In AWMD, japonica rice showed superior improvement in canopy temperature and quality.