IDENTIFICATION OF RESISTANT SOURCES TO COWPEA WEEVIL (CALLOSOBRUCHUS-MACULATUS (F)) IN VIGNA SP AND INHERITANCE OF THEIR RESISTANCE IN BLACK GRAM (VIGNA-MUNGO VAR MUNGO)

Seventy-five cultivated accessions and two wild progenitors of black g ram and mungbean were evaluated for their resistance to infestation by Callosobruchus maculatus. None of the cultivated accessions either of black gram or mungbean was found to be resistant. However, resistance was evident in a wild progenitor of black gram Vigna mungo var. silve stris. The mechanism of resistance of V. mungo var. silvestris was exa mined and it was found to be larval antibiosis expressed as reduced su rvival, longer developmental period and reduced body weight. V. mungo var. silvestris was successfully crossed with black gram accession TAU -1. In F-1 plants, pollen fertility was normal and seeds were complete ly resistant to C. maculatus. Inheritance of bruchid resistance was fu rther studied in F-2 and F-3 generations. In the F-2 generation, a 15: 1 ratio was observed indicating the presence of two dominant duplicate genes that are controlling resistance to C. maculatus. The segregatio n of F-3 plants was as expected for a digenic ratio and segregation sh owed a good fit to a 7:4:4 ratio (chi(2) = 0.28). These resistant gene s have been designated as Cmr(1) and Cmr(2). Copyright (C) 1996 Publis hed by Elsevier Science Ltd.