Effects of High Air Temperature on Rice Grain Quality and Yield under Field Condition
2013
Liu, Qihua | Wu, Xiu | Ma, Jiaqing | Li, Tian | Zhou, Xuebiao | Guo, Tao
High air temperature (HAT) limits grain yield and quality in rice (Oryza sativa L.). This study was conducted to determine the effects of HAT from R3 (panicle exertion from boot) to R8 stage (physiological maturity) on rice grain yield and quality (milling, appearance, cooking and eating, and nutrition qualities). A split-spot experiment based on randomized complete design was performed, involving two cultivars (japonica Koshihikari and indica IR72), two temperature treatments, and three replicates. Rice cultivars as main plot treatments were grown in a paddy field. The HAT and natural air temperature (NAT) treatments were regarded as subplot. Percentage of chalky kernel increased, whereas head rice yield, amylose and starch contents, and grain yield decreased in both cultivars under HAT, when compared with those under NAT. The HAT enhanced values of peak viscosity and breakdown, but decreased value of setback for Koshihikari. Conversely, starch viscosity characteristics for IR72 were unaffected by HAT. Relative content of amino acids in grains were enhanced; however, absolute content of some amino acids did not increase due to the reduction of grain weight under HAT. The HAT also increased absolute content of grain protein in IR72, but not in Koshihikari. The present study indicates that HAT decreased rice milling, appearance qualities and grain yield, while it positively influenced not only cooking and eating qualities in Koshihikari but also some nutritional components of grains in both cultivars.
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