Development of multiple disease resistant pre-breeding lines through interspecific hybridization between greengram (Vigna radiata) and ricebean (Vigna umbellatta)

The present study involves interspecific hybridization between ricebean (RBL 35) and six greengram varieties viz., CO6, CO7, CO8, VBN 2, VBN 3 and VBN 4. Successful interspecific hybrids were obtained from two crosses viz., CO 6 x RBL 35 and CO 8 x RBL 35. A total of 13 contrasting morphological characters among the parents were used for characterization of the interspecific hybrids. The traits viz., germination type, hypocotyl colour, leaf colour, terminal leaflet shape, growth pattern, inflorescence type, pod colour, pod pubescence, seed shape and hilum type were identified as dominant traits and were transmitted from ricebean, served as good indicators for earmarking true greengram x ricebean interspecific hybrids.The hybrids obtained from the cross CO 8 x RBL 35 were found to be completely sterile. However, the partial fertile hybrid with 5.60 per cent pollen fertility was obtained in the cross CO6 x RBL 35 with poor pod set. The seeds obtained from the above cross were advanced and found with an improvement of pollen fertility in F6 generation (80 %).The progenies were screened for four major diseases in five different seasons and was found to be resistant to yellow mosaic, powdery mildew, leaf crinkle and cercospora leaf spot diseases. Hence, the pre - breeding lines developed in this study could be used as donor for introgression of resistant genes into greengram.