Abstract: According to 16 prefectures and five rice cropping regions in Yunnan Province, 477 accessions of core collection of Yunnan rice landrace were identified for geographic distribution and cold tolerance at booting stage. The results showed:(1)There was a significant positive correlation(0.588 **) between anther length and seed setting rate under natural low temperature conditions but contrary in greenhouse(0.080). (2)There was comparablely significant difference in cold tolerance of core collection at booting stage under natural low temperature conditions while no basically cold damage in greenhouse(seed setting rate approached or exceeded 70%) at different rice cropping regions in Yunnan Province.Cold tolerance of core colletion at booting stage of northwest Yunnan cold highland japonica region was the strongest,but that of south marginal paddy-upland rice region was the weakest.Thus the breeding goals for cold tolerance were different on various rice cropping regions.(3)There was great difference in cold tolerance of core collection at booting stage under natural low temperature conditions while no basically cold damage in greenhouse(seed setting rate exceeded 65%) at different prefectures in Yunnan Province. According to seed setting rate reduction and characteristics of natural climates of different prefectures, 16 prefectures could be divided into three categories: region of serious cold damage, region of secondary cold damage and region of slight cold damage.(4)The significant difference of cold tolerance revealed further that temperature change caused by elevation and latitude was not only a dominant factor of differentiation of japonica and indica but also the basic reason that genetic diversity and six ecological groups of indica and japonica developed,even critical element that gene of cold tolerance produced.The cold tolerance at booting stage resulted from the synergetic evolution of Yunnan rice landraces and low temperature at different rice cropping regions or prefectures for a long time.

Key words: Yunnan rice landrace, core collection, cold tolerance, booting stage, rice cropping region, ecogeographic distribution

摘要： 以云南16个地州和5个稻作区为单位，对477份云南稻种核心种质进行了耐冷性鉴定及其地理分布研究。结果表明：（1）低温条件下花药长与结实率呈极显著正相关（0.588[sup]**[/sup]），温室条件下两者关系不大（0.080）。（2）低温条件下不同稻作区云南稻种核心种质孕穗期耐冷性差异较大，滇西北高寒粳稻区的稻种核心种质孕穗期耐冷性最强，南部边缘水陆稻区最弱。而温室条件下基本未受到冷害，结实率接近或超过70%。因此，耐冷育种目标和品种因稻区而异。（3）低温条件下不同地州云南稻种核心种质孕穗期耐冷性差异十分明显，而温室条件下基本未受到冷害，结实率均大于65%。根据稻种核心种质的结实率降低率及其地州间的自然气候差异，可将16个地州划分为重冷害区、冷害区和轻冷害区。（4）不同稻作区或不同地州间云南稻种核心种质孕穗期耐冷性的差异，进一步揭示了由海拔和纬度差异引起的温度变化不仅是籼粳分化的主导因子,也是造成籼粳两个亚种六大生态群之间差异和云南稻种遗传多样性大的根本原因，同时也是耐冷基因形成的关键因素，孕穗期耐冷性是云南地方稻种与地州或稻作区低温长期协同进化的结果。

关键词: 云南地方稻种, 核心种质, 耐冷性, 孕穗期, 稻作区, 地理分布