Multiple biotic stress resistant and productive genotypes identified under Spanish bunch background in groundnut (Arachis hypogaea L.)

The cultivated groundnut is an important oil seed crop of the world. Several pest and diseases damage the crop and reduce groundnut yields considerably. Cultivation of resistant varieties is an ecologically sound and economically viable approach to reduce the loss due to these stresses, but their occurrence and intensity vary in space and time necessitating the use of multiple stress resistant genotypes. Several diverse groundnut germplasm were assessed for different biotic stresses under epiphytotic conditions. Most of the cultivated varieties were susceptible to different stresses. Interspecific deri vati ves constituted the best source of resistance to late leaf spot (LLS), rust and Sclerotium; while mutants were superior for late leaf spot, Spodoptera and bud necrosis. Pedigree of multiple stress resistant genotypes revealed contribution of wild species for resistance to many biotic stresses. Trait association studies indicated late matUling nature of resistant germplasm. Induced mutagenesis and extensive hybridization with interspecific derivatives were sought to break these undesirable associations. Several foliar disease resistant mutants and second cycle interspecific-derivatives were isolated in Spanish bunch background. Mutant (28-2) and second cycle interspecific derivative (GPBD-4) were resistant to foliar diseases with high yield potential even under foliar disease epidemic. 28-2 was also resistant to Spodoptera, thrips and Aspergillus infection besides having bold kernels. GPBD-4 was iron absorption efficient and had OIL ratio of 1.68. They also possessed desirable agronomic features, early maturity, high partitioning and better quality. Mutant 28-2 and GPBD-4 have been registered with National Bureau of Plant Genetic Resources (NBPGR), New Delhi with INGR numbers 98003(IC296686) and 0 I 031 (IC2968LO), respectively. These cultures had stable and superior performance over popular cultivars (JL-24 and TMV-2) across years. GPBD-4 has been accepted by farmers and traders; under active seed chain and cultivation in the farmers' fields in India. GPBD-4 has been widely employed for MABC at ICRISAT and UASD as the source of resistance to LLS and rust.