Evidence of Geographical Divergence in Kabuli Chickpea from Germplasm Evaluation Data

Abstract

Turkey is the putative center of origin of cultivated chickpea, Cicer arietinum L. The large-seeded kabuli chickpea is the most common type cultivated in West Asia and the Mediterranean region. This type is believed to have diverged from its ancestral small-seeded, desi type in the Mediterranean region, and spread to India in the east and Chile in the west. Differences in agro-climatic conditions and farmers' preferences for the species may have produced geographical differentiation of interest both in agriculture and crop evolution. The objective of this study was to test whether geographical divergence in kabuli chickpea is consistent with the proposed theory of its spread from its putative center of origin. More than 4000 kabuli chickpea accessions representing Turkey and six other major chickpea-growing regions were grown in a winter-sown nursery at the International Center for Agricultural Research in the Dry Areas (ICARDA), near Aeppo, Syria, and characterized for nine morphological, three phenological and four physiological characters. Accessions in each region were grouped in three broadly defined classes: desirable, undesirable, and intermediate. These classes were determined on the basis of human preference and plant breeding experiences in the semi-arid Mediterranean region. Frequencies in respective classes were recorded for each character. Frequency distributions were significantly different among the regions. The highest frequency of accessions in the desirable class for eight of the 16 characters was found in the regions west of Turkey, and for four characters in the regions east of Turkey. Five traits; growth habit, canopy width, plant height, seed size, and days to maturity were used to examine multicharacter associations in different regions. The discrete log-linear multivariate analysis showed two-character associations, but no higher order associations in any region. The most frequently occurring association was between plant height and canopy width. Multivariate principal components analysis of 11 quantitative traits revealed that the distribution of chickpea on both sides of Turkey was consistent with the proposed pathway.