Evolution in the genus Cicer - vernalisation response and low temperature pod set in chickpea (C. arietinum L.) and its annual wild relatives

Abstract

Chickpea (Cicer arietinum) developed as a post-rainy season, spring-sown crop early in its evolution and spread into warm subtropical regions, in contrast to its wild relatives that have remained as winter annuals in West and Central Asia. To test whether these different life cycles selected for different phenological strategies in wild and cultivated Cicer, germplasm from a wide range of habitats was subjected to different cold treatments (vernalisation, control) at germination, and phenology evaluated at warm and cool field sites (14.8–15.1°C and 13.1°C, respectively). All wild Cicer species, except for C. yamashitae, responded positively to vernalisation and accelerated the dates of flowering, podding, and maturity. There was no vernalisation response in cultivated chickpea, whereas C. arietinum/C. echinospermum and C. arietinum/C. reticulatum interspecific hybrids were intermediate, flowering 6–16 days earlier after vernalisation. Relative podding dates differed between sites. Chickpea podded earlier than most vernalised wild species under warm conditions, but not at the cool site. Regression against post-anthesis temperature showed that the delay in podding was consistent with a lack of cold tolerance in the cultigen. The interspecific hybrids were significantly more cold tolerant than chickpea, and the wild species were almost insensitive to the temperature range recorded at the cool site. Vernalisation responsiveness and a greater tolerance of low temperatures during the reproductive phase demonstrate that the annual wild Cicer species harbour important traits that can be used to widen adaptation in the cultigen, and may help to improve the performance of chickpea as a Mediterranean cool-season crop.