Geographical distribution and cold tolerance at booting stage of the second core collection of rice landraces (Oryza sativa) from Yunnan, China

摘要

The second core collection of rice land-races (Oryza saliva L.) from Yunnan, China consisting of 696 accessions, grouped according to rice-cropping regions and administrative districts, was investigated with respect to the geographical distribution and cold tolerance of accessions at booting stage. The results showed distinct differences in cold tolerance at booting stage of accessions originating from different rice-cropping regions and prefectures. The degree of cold tolerance ranged from highest to lowest in the following order: northwest Yunnan cold highland japonica rice region > central Yunnan single-season japonica-indica region > northeast Yunnan plateau japonica rice region > south Yunnan single/double-season rice region > south marginal paddy-upland rice region. The breeding goals for cold tolerance differed among the various rice-cropping regions. The rice-growing areas of Yunnan can be divided into three categories based on the severity of cold damage experienced, namely serious or severe cold damage; moderate cold damage; and slight cold damage regions. These geographical differences were the dominant factor in producing the range of genetic diversity in cold tolerance found in the rice landraces of Yunnan. Differences in cold tolerance at booting stage result from the fact that the Yunnan rice landraces and the amount of cold damage expected in the different rice-cropping regions have co-evolved over a long period of time.