A major gene for flowering time in chickpea

Water availability is a major yield-limiting factor in semi-arid regions. Hence, efficient utilization of soil water for grain production depends on correct timing of flowering. Following winter (December-January) sowing, modern Israeli chickpea (Cicer arietinum L.) cultivars begin flowering during the last week of March and their reproductive period extends throughout April to June. In the Middle East, April, May, and June are often dry and hot months. The objectives of this study were (i) to assess the potential range of chickpea germplasm as a source for early flowering, and (ii) to study the inheritance of the time to flowering trait. Germplasm evaluation was carried out by measuring days from germination to flowering and calculating phenotypic correlations between days to first flower, grain weight, and pod number along main branches. A number of early-flowering genotypes were identified, and weak association between flowering time genes and seed weight loci was observed. Crosses were made between types of contrasting photoperiod response. In F₂ populations derived from crosses between an early-flowering breeding line (desi) with weak photoperiodic response and a late-flowering high-yielding (kabuli) cultivar with a strong photoperiod response, a 3:1 ratio of late-flowering: early-flowering types was observed. This segregation is consistent with action of a major photoperiod response gene (Ppd) affecting time to flowering. Considerable genotype x environment interaction was observed among F₃ progeny of these crosses. The relatively simple inheritance of the photoperiodic response observed in this study suggests that the early-flowering trait may be easily introduced into popular late-flowering genetic backgrounds.