Identification of QTLs for seedling vigor in winter wheat

Seedling vigor is an important trait characterized by rapid development of vegetative cover above the soil surface, particularly in rainfed environments. To elucidate the genetic basis of seedling vigor, 207 F2:4 lines derived from Jingdong 8/Aikang 58 were investigated in the field at Beijing and Gaoyi, Hebei province, during the 2011–2012 and 2012–2013 cropping seasons. A total of 148 SSR markers polymorphic between the parents, and the RhtD1b-specific marker were used to map QTL for seedling vigor by inclusive composite interval mapping (ICIM). Normalized difference vegetation index (NDVI) and ground cover (GC) before winter and in late spring showed a continuous distribution. Significant differences in NDVI and GC among lines were detected. Broad-sense heritability of NDVI and GC ranged from 0.69 to 0.74 based on the mean values averaged across four environments. GC was highly correlated with NDVI (r = 0.74–0.85, P