Cyto-taxonomic evidence for the affinity betweenCajanus indicus, spreng. and certain erect species ofAtylosia W. & A.

Abstract

A close affinity ofCajanus indicus Spreng. with certain erect species ofAtylosia particularlyA. lineata W. & A. andA. sericea Benth., is indicated on morphological, taxonomical and cytogenetical grounds as also from the homology of some normal and mutant characters in the two genera and high fertility of certain inter-generic hybrids.A. lineata andA. sericea have the same chromosome numbers asCajanus indicus (2n=22).A. lineata andA. sericea are highly resistant toTur pod-boarer (Exelaster atomosa, W.) andTur wilt disease caused byFusarium udum Butler. Besides the utility ofAtylosia species as a soil conserving leguminous forage cover crop, they can be utilised for evolving superior strains of cultivatedCajanus indicus combining hardiness, perennial growth habit, tolerance to summer drought on poor eroded soils and high degree of resistance to certain pests and diseases. Occurrence of only a single reported species ofCajanus in India imposes certain limitations on the scope for its improvement through breeding. The evidence regarding its close affinity with certain erect species ofAtylosia opens fresh avenues for breeding and improvement ofTur, which is one of the most important grain pulse crops of India. In the light of evidence for their close affinity, it is suggested that erect stem species ofAtylosia may be incorporated in the genusCajanus and the two genera may be taxonomically revised.