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Effect of High Night Temperature During Grain Filling on Amyloplast Development and Grain Quality in Japonica Rice

¹Key Laboratory of Physiology, Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, 450002, People's Republic of China.²Department of Food Science and Engineering, Henan Agricultural University, Zhengzhou 450002, People's Republic of China.³Key Laboratory of Crop Physiological Ecology and Farming System, Huanghuaihai, Ministry of Agriculture, Zhengzhou 450002, People's Republic of China.⁴Corresponding author. Wenhua Road, No. 95, Zhengzhou 450002, Henan Province, People's Republic of China. Phone/Fax: +86-371-63558126. E-mail: rcrekl@163.com, qzzhaoh@126.com

High-quality japonica rices Yujing 6 and Fangxin 4 were cultured under ambient night temperature (ANT, 19.7°C) and high night temperature (HNT, 26.7°C) in a greenhouse for the analysis of amyloplast development and grain quality during the grain-filling stage. Results indicated that the HNT treatment had distinct effects on the grain-filling rate of Yujing 6 and Fangxin 4 1–10 days after anthesis. HNT increased the rate of grain filling by 9.89–40.45% and decreased the accumulation of grain-filling matter, resulting in inferior appearance and poor milling qualities (e.g., brown rice rate, milled rice rate, head rice rate, imperfect rice rate, chalky rice rate, and chalkiness degree). Results from a rapid viscosity analyzer showed that the HNT treatment decreased the paste viscosity, depending on the rice cultivar. Differential scanning calorimetry results indicated that the gelatinization temperatures of HNT such as onset temperature, peak temperature, and final temperature were all significantly higher than those of ANT. However, HNT had no distinct effects on the X-ray diffraction pattern of rice starch.