Method for evaluating rice quality based on the daily effect of meteorological factors

Rice is one of the important food crops in Asian areas. High-quality rice can be cultivated as a pivotal direction for the advancement of the rice industry. Environmental meteorological conditions can represent a significant influencing factor in the formation of rice quality. Consequently, this study aims to elucidate the suitable meteorological parameters for high-quality rice. A quantitative evaluation model of rice quality was constructed using meteorological factors. Regional climatic resources were fully utilized to enhance the quality of rice. The daily meteorological data was collected from the regional trials in Anhui Province, China, from 2008 to 2021. The mid-season indica and japonica rice varieties were taken as the research materials. The parameters of rice quality were also collected, including the head rice yield, chalkiness, transparency, alkali spreading value, gel consistency, and amylose content. The meteorological data included the average daily air temperature (℃), the maximum air temperature (℃), the minimum air temperature (℃), and radiation (MJ/m²). The meteorological index was constructed to comprehensively influence the rice quality. The quality of indica and japonica rice was also evaluated using the daily impact of meteorological factors. A correlation analysis, computer numerical simulation, and regression analysis were employed to validate the model. The data was also taken from the staged sowing trials conducted in Lujiang County in 2018, Chizhou City in 2023, and Hefei City in 2023. The results showed that: The critical period for the formation of rice quality was 31 and 35d after the full-heading date for the mid-season indica and japonica rice, respectively. The optimum daily mean temperature for the formation of mid-season indica rice quality was 24.5 ℃. The optimum daily radiation and daily range in temperature were more than 15.2 MJ/m² and 12.1 ℃ higher, respectively. In the formation of the quality of mid-season japonica rice, the optimum daily mean temperature was 22.7 ℃, and the optimum daily radiation and daily range in temperature were more than 14.7 MJ/m² and 10.9 ℃ higher, respectively. The optimal temperature, sufficient radiation, and relatively large daily range in temperature difference were important meteorological conditions for the formation of rice quality. The composite meteorological index was used to determine the rice quality grading criteria. The composite meteorological indices (y_c1) corresponding to the mid-season indica rice quality grades were: y_c1≥28.35, 26.87≤y_c1<28.35, 25.12≤y_c1<26.87 and y_c1<25.12 from the first-class to the normal grades. The composite meteorological indices (y_c2) corresponding to the mid-season japonica rice quality grades were: y_c2≥30.31, 28.88≤y_c2<30.31, 26.89≤y_c2<28.88 and y_c2<26.89 from the first-class to the normal grades. It was verified that the back substitution accuracy of the mid-season indica and mid-japonica rice quality evaluation models were 72.3% and 78.7%, respectively, and the accuracy of the simulation was 72.2% and 73.3%, respectively. Quantitative assessments were also performed on the impact of meteorological conditions on the quality of rice. The finding can offer a theoretical foundation to fully utilize the regional climate resources, in order to enhance the quality of rice.