Geographical patterns of variation for morphological and agronomic characteristics in the chickpea germplasm collection

The characterization of diversity in germplasm collections is important to plant breeders for crop improvement and to genebank curators for efficient and effective management of collection. The objective of our study was to describe the phenotypic diversity of the 16 820 accessions of chickpea (Cicer arietinum L.) germplasm contained in the ICRISAT genebank. The germplasm accessions were characterized for seven morphological descriptors, reaction to fusarium wilt, and 13 agronomic traits to determine phenotypic variation in different geographical regions. Phenotypic variation was found for most traits in all the regions. The means for different agronomic traits differed significantly between regions. The variances for all the traits among regions were heterogeneous. South Asia contained maximum range variation for all the traits. The Shannon-Weaver diversity index was variable in different regions for different traits. Among morphological traits seed colour and among agronomic traits days to 50% flowering showed the highest pooled diversity index. The Mediterranean region, which is the primary center of diversity, and Africa, which has the secondary center of diversity in Ethiopia, were poorly represented. Principal component analysis (PCA) using 13 traits and clustering of the first three PC scores delineated two regional clusters consisting Africa, South Asia, and Southeast Asia in the first cluster and the Americas, Europe, West Asia, Mediterranean region, and East Asia in the second cluster.