Heading date QTL in rice derived from an analysis of chromosome segment substitution lines

With 5 figures and 3 tables Abstract The inheritance of heading date (HD) in rice was investigated using a set of lines in which chromosome segments of the photoperiod‐ and temperature‐sensitive male sterile line Peiai 64S had been incorporated into a genetic background of the cv. 9311. The flowering time of each line was contrasted with that of cv. 9311 in four distinct environments: natural long days (13.2–14.2 h photoperiod) and artificially shortened days (9 h photoperiod) at Nanjing; and natural (low) temperature and enhanced temperature at Hainan. A set of 21 heading date quantitative trait loci (QTL) was identified, covering eight of the 12 rice chromosomes, and their dependence on photoperiod and/or temperature was characterized. Two of the QTL were photoperiod‐sensitive, and eight were insensitive; while two were temperature‐sensitive and four insensitive; the remaining five QTL were independent of both temperature and photoperiod. Based on its segregation in an F2 population bred from the cross CSSL C053 × cv. 9311, the temperature‐ and photoperiod‐insensitive QTL qHd‐8‐4 was mapped within a segment of chromosome 8 flanked by the SSR marker RM22469 (1.9 cM) and RM72 (2.4 cM).