Using host plant resistance to manage biotic stresses in cool season food legumes

Summary Kabuli chickpea (Cicer arietinum L.) is the common cultivated type of chickpea in arid and semi-arid environments in the Mediterranean region. Ascochyta blight, (Ascochyta rabiei (Pass.) Labr.), leaf miner (Liriomyza cicerina, Rond.) and cold, are the three most important stresses on chickpea grown under semi-arid conditions in this region. Phenotypic frequencies for responses to these stresses in the eight major chickpeagrowing regions of the world were estimated from 5,672 kabuli chickpea accessions assembled from these regions. In addition, the accessions were evaluated for 12 morpho-physiological and three phenological characters under semi-arid Mediterranean conditions at the International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria. Considerable regional differences in frequency distributions for response to the three stresses were observed. Average phenotypic diversity for responses to the three stresses was lower (H_o=0.474) than for morpho-physiological (H_o=0.754) and phenological (H_o=0.812) characters. The highest frequencies of accessions resistance to Ascochyta-blight and leaf-miner were found in South Asia and South Central Asia, respectively. A small number of chickpea breeding materials of ICARDA showed a moderate level of tolerance to cold. A group of four characters showing the strongest bivariate association with each of the three stresses was identified from the latter group. Then, a discrete multivariate log-linear analysis of the five-way frequency table was performed for each group. The simplest log-linear model for each group included both two- and three-factor association terms, but no independent factors. This suggested the potential for indirect selection for stress tolerance using one or more of these associated characters. The roles of these characters in ideotype breeding of kabuli chickpea for arid and semi-arid Mediterranean conditions deserves careful assessment.