The improvement of Phaseolus vulgaris as a grain legume crop in Malaysia: Induction of an erect bush type

A programme to improve on an introduced variety of dry bean was started in 1980. The variety is an indeterminate climber and the aim is to produce an erect bush type using the technique of mutation induction by gamma rays from a 60Co source. From the results of preliminary studies carried out under greenhouse and field conditions, a procedure for handling the M1 and M2 generations has been developed. A total of 2,264 cell initials irradiated with 30 Krads has been screened. A number of possible mutants have been selected from the single seed bulk (Bsub(s)) and the single pod bulk (Bsub(p)) of the M2 generation. These mutants are being tested in the field as progeny rows of the M3 generation. In addition, the paper discusses plant architecture, the current knowledge of the genetics of the characters which contribute to the architecture of the plant, its relationship to yield and breeding, and the breeding strategies that should be adopted in this programme. (author)