Assessment of genetic diversity in linseed germplasms for Alternaria blight resistance under natural conditions

Aim: The aim of the present study was to identify the resistant varieties/entries of linseed against Alternaria blight disease and recommend them for cultivation in epidemic areas. Methodology: A total of 144 linseed germplasms were field-screened for resistance to Alternaria blight at Bihar Agricultural University, Sabour, during the Rabi seasons of 2020–21, 2021–22 and 2022–23. Standard non replicated field trials with controls were conducted, and disease response was assessed at multiple growth stages. Entries were classified as resistant, moderately resistant, moderately susceptible, or highly susceptible based on their disease reaction. Results: Out of 144 linseed germplasm screened, seven entries were found to be resistant to Alternaria blight: CI 1552, GS 440, H 40, LC 2945, PKDL 167, Priyam and RL 15561. Additionally, 22 entries exhibited moderate resistance, while 60 entries showed moderate susceptibility to the disease. Remaining entries were either susceptible or highly susceptible to Alternaria blight. Interpretation: The identified resistant and moderately resistant linseed entries can be recommended for cultivation in Alternaria blight-prone areas to mitigate disease impact. Their use can help minimize yield losses, reduce reliance on chemical control, and support sustainable linseed production. Susceptible varieties should be prioritized for genetic improvement using resistant gene pools. Key words: Disease resistance, Genotype screening, Linseed, Natural condition