Identification of resistant sources through field evaluation of soybean genotypes against anthracnose caused by Colletotrichum truncatum (Andrus and Moore)

Abstract

Soybean (Glycine max (L.) Merr.) is an important oilseed and protein crop, yet its productivity is severely constrained by anthracnose/pod blight caused by Colletotrichum truncatum, particularly under warm and humid conditions. The present study was undertaken to evaluate the response of forty soybean genotypes to anthracnose under natural epiphytotic field conditions during the Kharif season of 2024-25 at the Regional Sugarcane and Rice Research Station, Rudrur, Telangana. The results revealed significant variation in disease incidence and severity among the genotypes with PDI ranging from 46.7 to 100.0 percent. None of the genotypes exhibited complete resistance to anthracnose. Three genotypes, namely Basara, ASB 206 and RSB 1070 showed a moderately resistant reaction recording comparatively lower disease severity and restricted symptom development. Seven genotypes were categorized as moderately susceptible, while the majority of the entries were classified as susceptible to highly susceptible exhibiting severe stem, pod and foliar infections. The wide variability in disease response reflected differences in host-pathogen interactions under field conditions. The identification of moderately resistant genotypes highlights the presence of partial resistance within the evaluated germplasm which can contribute to reduced disease impact and yield loss. These genotypes represent valuable donor sources for breeding programs aimed at developing anthracnose-tolerant soybean cultivars. The study emphasizes the need for continued screening of diverse germplasm to identify stable and durable sources of resistance for sustainable management of soybean anthracnose.