Abstract:

【Objective】 This study aims to investigate the impact of high-temperature stress during the filling stage on the milling, appearance, cooking, and eating quality of early indica rice and to reveal the response patterns of quality traits in early indica rice to high temperatures during the filling stage. 【Method】 Experimental materials included R996, Xiangzaoxian 45, and six newly bred early indica rice varieties. Natural high-temperature stress treatment was applied through staged sowing. The milling, appearance, and cooking and eating qualities of the eight varieties were analyzed. Heat-insensitive and heat-sensitive rice varieties were identified, and the response of rice quality to high temperatures during the filling stage was explored. 【Result】 Temperature within 10 days after heading had the most significant impact on the milling quality and cooking and eating quality of rice, while temperature within 30 days after heading had the most significant effect on the appearance quality of rice. High-temperature stress significantly reduced the brown rice rate, milled rice rate, head rice rate, and grain length, increased chalky grain rate and chalkiness, and adversely affected milling quality and appearance quality of rice. The amylose content was significantly reduced, whereas rice comprehensive score, appearance, taste, and viscosities were significantly improved, enhancing rice palatability. Rice varieties exhibited varying responses to high-temperature stress based on specific quality traits. Q3, Q8, Q11, and Q13 were identified as high-temperature-insensitive varieties, according to the high-temperature stress index (HTSI) for milling quality. However, Q3, Q4, Q5, and Q11, which demonstrated excellent cooking and eating quality under high-temperature growth conditions, were classified as high-temperature-insensitive varieties based on the high-temperature stress index for appearance quality. 【Conclusion】 High-temperature stress during the grain-filling period reduced the milling quality and appearance quality of rice but improved rice palatability. Rice varieties Q3 and Q11, characterized by good milling quality, appearance quality insensitive to high temperatures, and good cooking and eating quality, hold promise as new germplasm for the high-quality breeding of early indica rice.

Key words: early indica rice, filling stage, high temperature stress, rice quality

摘要：

【目的】研究灌浆期高温胁迫对早籼稻碾磨、外观和蒸煮食味品质的影响，揭示早籼稻品质性状对灌浆期高温胁迫的响应规律。【方法】以R996、湘早籼45号和6个新育成的早籼稻品系为试验材料，以分期播种方式利用自然高温进行胁迫处理，分析了供试品系的碾磨、外观和蒸煮食味品质，筛选出对高温钝感和敏感的水稻品系，探究稻米品质性状对灌浆期高温胁迫的响应规律。【结果】稻米品质性状对灌浆期不同时段温度的敏感性不同，始穗后10 d内温度对稻米碾磨品质和蒸煮食味品质影响最显著，始穗后30 d内温度对稻米外观品质影响最显著。稻米品质对灌浆期高温胁迫的响应因性状而异，灌浆期高温胁迫显著降低糙米率、精米率、整精米率和粒长，显著提高垩白粒率、垩白度，劣化了稻米碾磨品质和外观品质；显著降低直链淀粉含量，提高米饭外观、米饭口感和米饭黏度，提升了米饭适口性。水稻品系对高温胁迫的响应因稻米品质性状而异，Q3、Q8、Q11、Q13属于碾磨品质高温钝感品系，Q3、Q4、Q5和Q11属于外观品质高温钝感品系且高温下蒸煮食味品质优。【结论】灌浆期高温胁迫会降低稻米的碾磨品质和外观品质，提高米饭适口性。水稻品系Q3和Q11碾磨品质、外观品质好且高温钝感，蒸煮食味品质优良，可望为早籼稻优质育种提供新的种质资源。

关键词: 早籼稻, 灌浆期, 高温胁迫, 稻米品质