Relationship between Cold Tolerance at the Budbursting Period and Other Traits Related to Cold Tolerance in Rice

Genetic variation of cold tolerance at the budbursting period (CTBP) and its relationship with some agronomic traits related to cold tolerance were studied by using F 3 lines derived from a cross between indica and japonica “Milyang 23/Jileng 1”. A continuous distribution near to normal for CTBP was observed in F 3 lines, suggesting that CTBP was a multigenic quantitative trait. Seedling growth ability, days to heading, panicle exsertion, cold tolerance at the booting stage (seed setting rate in low temperature) and phenotypic acceptability under natural low temperature or cold water irrigation were significantly correlated with CTBP. Seedling growth ability, cold tolerance at the booting stage, phenotypic accepta- bility and panicle exsertion of selected lines with high CTBP were better than those of selected lines with low CTBP and unselected F 3 lines. Through selection of CTBP in lower generation derived from cross of indica and japonica can obtain good lines with higher seedling growth ability, cold tolerance at the booting stage and phenotypic acceptability.