Abstract

Groundnut rosette disease is one of the most damaging diseases militating against groundnut production in sub-Saharan Africa. The disease cause up to 100% yield loss whenever epidemic occurs. The most effective, economic and environmental friendly method to control the disease is through genetic resistance. Knowledge on inheritance of resistance to the rosette disease is required to accelerate breeding of resistant varieties. A study was conducted to understand the nature and magnitude of gene effect of resistance to the disease. Thus F1, RF1, F2, RF2, BC1, RBC1, BC2, and RBC2 progenies were derived from crosses of Otuhia × Manipintar, Otuhia × Shitaochi, ICGV 01276 × Manipintar, and ICGV 01276 × Shitaochi along with their parents were evaluated in a randomized complete block design at CSIR - CRI, Fumesua, under artificial infection. Generation mean analysis revealed that additive gene action effect was predominant on the resistance to the disease in all the crosses. Additive by dominance was the only form of non-allelic interaction observed to be significant in ICGV 01276 × Manipintar cross. Reciprocal differences suggested the presence of maternal effect involved in the inheritance of resistance to groundnut rosette disease. Estimates of broad and narrow sense heritability indicated that genetic effect was larger than the environmental effects in this study. Disease diagnosis using TAS ELISA revealed the presence of groundnut rosette assistor virus (GRAV) antigens in the resistant samples analyzed. Resistant genotypes containing GRAV were considered to be resistant to the GRV and its Sat-RNA, but not the GRAV which causes no obvious symptoms by itself. Pure line breeding with selection from early generation is suggested for the improvement of resistance to rosette virus disease, because additive genetic effect contributed significantly in controlling the inheritance of resistance to groundnut rosette disease (GRD).

Key words: Additive, dominance, heritability, inheritance, heterosis, rosette disease.