Evaluation of groundnut genotypes for resistance to Sclerotium rolfsii under artificial field inoculated conditions

Stem and pod rot caused by Sclerotium rolfsii is the major constraint to groundnut production in many groundnut growing regions of the world. Paucity of suitable field screening methods to identify sclerotium resistant genotypes hinders the progress of resistance breeding. A sick plot with high inoculum load of Sclerotium rolfsii, was established. A total of 165 sergeants derived from TAG 24 (adopted but susceptible variety) . R 9227 (stem rot resistant variety) were screened for resistance to stem and pod rot. The Fs and F6 generations were grown in the sick plot to confirm their reaction to stem and pod rot. Among different parameters, variation was highly heritable for yield per plant, disease incidence parameters potential for selection under disease epidemics. Strong negative association between disease incidence and yield per plant revealed the importance of disease incidence in determination of yield per plant under epiphytotic conditions. The higher number of superior segregants observed for p0d weight per plant (26), oil content (21), test weight ( 19) and shelling percentage (8) and disease at harvest (6) were compared to both the parents. None of the genotypes showed complete resistance. It is unlikely that highly resistant genotypes to neurotropic pathogen like Sclerotium rolfsii would be identified. However information obtained on genotypic variance, heritability, genetic advances and association of disease with yield and lines selected with considerable sclerotium resistance with good yield attributing characters (6) can be utilized in future breeding programs.