[Objective] The chilling damage in summer was a main cause resulted in output reduction of Yunnan rice.In order to accurately assess and predict the impact of summer low temperature on rice yield in Yuxi city,the climatic characteristics,main influencing factors and indices of summer chilling damage for local japonica rice were analyzed.[Method] Based on the data of growth stages,empty shell rates of rice and climate data from 1981 to 2010 at Agro-meteorological station of Yuxi city,this study was carried out by means of the contrastive analysis on climatic conditions for typical years,principal component analysis and linear regression.[Result] The result showed that booting and heading stages were the important sensitive phase of chilling damage for japonica rice and minimum temperature was the primary factor which caused rice chilling damage.The temperature during the summer was generally lower in the central region of Yunnan and its internal fluctuation was marked,while it was rainy with scant light,which gave easily rise to chilling injury of rice.Under the climatic conditions in central Yunnan,rice was more sensitive to night low temperature before head sprouting than daytime low temperature,while it was more likely to suffer damage because of daytime low temperature during heading to flowering stage.[Conclusion] The critical indices of chilling damage for japonica rice in central Yunnan were presented,the average value of minimum temperature for 2 successive days was 15.5 ℃ and the average maximum temperature for 3 successive days was 22.5 ℃ in summer.The major meteorological factors affecting local rice chilling damage in summer included the mean minimum temperature from the 11 th to 5th days before heading date of rice,mean maximum temperature from the 2nd day before heading date to the 4th days after heading date of rice,and mean temperature of the two date time frames.These three meteorological factors were combined to structure an integrated climatic index H,which was highly negatively correlated with the rate of rice shell,meaning an ability to express the summer chilling damage of japonica rice to a certain extent in central Yunnan.%[目的]夏季低温冷害是云南水稻减产的主要原因之一,文章为准确评估、预测低温冷害对水稻产量的影响展开研究.[方法]基于36年水稻物候和空壳率及气候资料,使用相关、主成分和回归分析与典型年水稻冷害气候分析相结合,研究粳稻夏季低温冷害的气候特点和指标.[结果]孕穗抽穗期是粳稻低温冷害的主要敏感期,滇中地区一季稻夏季冷害对夜间低温较为敏感,最低气温是引发冷害的首要因素;滇中夏季气温典型偏低、多雨寡照特征和气温波动明显,从而易于引发水稻低温冷害.[结论]连续2d最低气温均值15.5℃、连续3d最高气温均值22.5 ℃可作为滇中水稻夏季冷害的参考性临界指标;使用抽穗前11-5 d最低气温和抽穗前2d至抽穗后4d最高气温及此二时段平均气温构建了夏季低温冷害综合指标H,它与水稻空壳率呈高度负相关,对滇中粳稻夏季低温冷害有一定的表征能力.
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