Enhancing phenotyping accuracy for stem rot disease through advanced oxalic acid assay in groundnut

Abstract

Abstract Background Stem rot, caused by Sclerotium rolfsii, is an important and difficult to manage soil borne disease in groundnut. This disease is seen in almost all groundnut growing regions in the world. It affects the crown region of the plant that make the whole plant collapse and leading to yield losses up to 80%. Results Comprehensive evaluation of 184 minicore germplasm accessions encompassing various subspecies and botanical varieties including checks in combination of sick field screening and response to oxalic acid assay resulted in indicating the presence of substantial variability for the trait among the genotypes. Further, the trait governing stem rot resistance, exhibited a significant environmental influence, but displayed high heritability and genetic advance, thus suggesting considerable potential for improvement through plant breeding strategies. The response to oxalic acid assay demonstrated good correlation with approximately 80% when compared with field assessments. Overall, seven genotypes such as ICG163, ICG721, ICG10479, ICG875, ICG11457, ICG111, and ICG2857 exhibited stable resistance against stem rot across multiple seasons in both the field and under controlled conditions. Conclusions Seven genotypes that are identified as resistance will be beneficial to introgression of resistance to elite genotypes. As the trait is highly influenced by the environment it is imperative to employ multi-season phenotyping. The oxalic acid assay developed and deployed in this study is complementing field phenotyping. It can be used in conjunction with the field phenotyping as it is difficult to maintain the uniform disease pressure across the field.