Development of a selection tool for seed shape and QTL analysis of seed shape with other morphological traits for selective breeding in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is an annual diploid (2n= 2x= 16) grain legume, grown worldwide for human consumption. Selection for variation in the physical seed characters of chickpea will enable future strategic breeding of varieties with the potential to attract premium prices in overseas markets. Seed shape is therefore a major current breeding objective, for which an understanding of the genetics of inheritance is required. For this, two recombinant inbred line (RIL) populations derived from intraspecific crosses of a kabuli-type (S95362; light cream colour) crossed to two desi-types (Howzat and ICC3996; medium tan and dark tan colour, respectively) were studied. In order to discretely characterize seed shape, a new Roundness Index (RI) tool was developed, calculated from the ratio of two seed size indices (SSI). The genetic parameters estimated were genotypic and total phenotypic variance for RI, genotype vs environment interaction and broad sense heritability. The low genotype x environment interaction (<9% of total variation for both populations) and high magnitude of heritability suggested the environmental stability of the seed shape trait. Segregation ratios for different seed shape among the RIL populations indicated control of seed shape under two genes. Subsequently, one putative quantitative trait loci (QTL) was identified on linkage group LG 2 between markers TA110-TA27 and accounted for 9% of the phenotypic variance. One QTL for stem colour and flowering time also detected on LG 2 between markers TR58-TR19 (explained 16% phenotypic variance) and LG 3 between markers TS19-TR56 (explained 23% phenotypic variance) respectively.