The exploitation of natural genetic variability for tthe improvement of chickpea (Cicer arietinum L.).

Abstract

The two main types of cultivated chickpeas of interest to plant breeders are the small-seeded desi types adapted to “winter” (Oct./Nov.) plantings in eastern Asia and the large-seeded kabuli types adapted to “summer” (Mar./Apr.) plantings in western Asia. These two types have most probably been separated for thousands of years. The total world area under chickpea cultivation is about 10.5 million hectares. India, Pakistan, and Ethiopia produce 74, 10, and 4% of the world’s crop, respectively. The world’s average productivity at approximately 710 kg/ha is very low. Breeding programs have to date made little impact on yield improvement, and most farmers continue to grow ancient land races on soils of low fertility and under rainfed conditions. ICRISAT began a breeding program in 1973 with the aim of producing elite lines and segregating populations to strengthen national and regional programs for the chickpea-growing countries of the world. Classic and recurrent selection breeding methodologies are being employed. In India, the breeding program of ICRISAT is carried out at Hyderabad (lat. 17°N) and at Hissar (lat. 29.5°N). In 1975 a “summer,” off-season (for India) nursery was grown in Lebanon. The crop in Lebanon proved highly informative with regard to divergencies between kabuli and desi types. Adaptability of coadaptation appears to be most important in chickpeas. Transgressive segregation is greater in kabuli X desi crosses than between same-group crosses. The introgression of kabuli germ plasm into desi germ plasm is important for the improvement of the desi crop in eastern Asia and the introgression of desi germ plasm into kabuli germ plasm for the improvement of the kabuli crop in western Asia. A superior cultivar for eastern Asia is more likely to be produced from a (kabuli X desi) X desi backcross and for western Asia by a (kabuli X desi) X kabuli backcross. Whereas initial gains are more likely to come from intraspecific hybridization, current evidence suggests the potential importance of interspecific hybridization involving Cicer arietinum and C. reticulatum. Cytogenetic studies of hybrids between cultivars of Cicer arietinum and C. reticulatum indicate chromosome repatterning within C. arietinum, which may indicate cytogenetic differences between cultivar groups within the cultivated species.