| Rice quality can inexplicably vary from one lot to another, and from year to year. A historical data analysis was performed that indicated that variable temperatures experienced during the nighttime hours of rice kernel development could be the cause of quality variation. A controlled temperature study using phytotrons, or large growth chambers, testing four nighttime temperatures of 18, 22, 26 and 30°C, using six rice cultivars (Cypress, LaGrue, XP710, XL8, M204, and Bengal), was conducted during the fall of 2004. As nighttime temperature increased, head rice yields (HRYs) decreased for all cultivars except Cypress and Bengal, for which HRYs did not vary among nighttime temperature treatments. In general, grain dimensions decreased as nighttime temperature increased. The number of chalky kernels increased with an increase in nighttime temperature for all cultivars but Cypress. The amylose content of Cypress and Lagrue significantly decreased at the nighttime temperature of 30°C. |
