Screening of Amaranthus Genotypes for Resistance to Leaf Blight Caused by Rhizoctonia solani

Amaranthus is a nutrient-rich leafy vegetable grown in tropical and subtropical regions. Leaf blight caused by Rhizoctonia solani is a major constraint in amaranthus production. In the present study 45 amaranthus genotypes were screened twice under field conditions for resistance against R. solani and the resistant lines identified were screened in-vitro with artificial inoculation. Disease severity varied widely, with PDI values ranging from 0.0 to 88.48 in 2024 and 0.0 to 96.66 in 2025. The accessions VLKAM-25, VLKAM-41, and VLKAM-42 were completely immune, while VLKAM-36 was highly resistant in both field screenings. The lines showing immune to moderate resistance in the field when screened in vitro, the accession VLKAM-41 remained free of symptoms, and VLKAM-25, VLKAM-36, and VLKAM-42 showed only limited lesion development. In contrast, the checks Arun and KAU Vaika developed large, coalescing lesions. The immune and highly resistant genotypes were identified as Amaranthus spinosus (VLKAM-41), A. hypochondriacus (VLKAM-25 & VLKAM-36), and A. dubius (VLKAM-42).