REACTION OF LINSEED (LINUM USITATISSIMUM L.) GERMPLASM FOR RESISTANCE TO FUSARIUM WILT CAUSED BY FUSARIUM OXYSPORUM F. SP. LINI

Abstract

Fusarium wilt, caused by Fusarium oxysporum f. sp. lini, is one of the most destructive soil-borne diseases limiting linseed (Linum usitatissimum L.) production worldwide. The pathogen persists in soil for prolonged periods and infects plants at different growth stages, resulting in severe yield losses and reduced crop productivity. The development and deployment of resistant cultivars remain the most economical, environmentally sustainable, and durable strategy for disease management. The present investigation was undertaken to evaluate twenty-five linseed germplasms for their resistance to F. oxysporum f. sp. lini under controlled and natural disease conditions using test-tube inoculation, artificially inoculated pot culture, and natural field screening. Germplasm accessions were collected from All India Coordinated Research Project on Linseed, Bihar Agricultural University, Sabour. Disease reactions were categorized as resistant, moderately resistant, moderately susceptible, susceptible and highly susceptible based on percent wilt incidence. Under artificial screening conditions, wilt incidence ranged from 0 to 100% and under natural field conditions from 5 to 98%, indicating significant genetic variability for resistance among the evaluated germplasms. Of all the entries screened by different methods, Neelam was found to be the most resistant. ST-4, ST-3, BRLS 106-1, BRLS 137, VKS 14-2, JRF-2, Parvati, Priyam, H-40 and Kartika also showed resistant reaction under artificial and field conditions. In contrast, BRLS 110-7, BRLS 109-5, BRLS 132-1, Pratap Alsi-2 and RLC 173 were highly susceptible indicating that these genotypes may not be useful for resistance but can be used as susceptible checks for future screening programs. The uniformity of resistance observed across different screening environments suggests that these germplasms are dependable as potential donor parents for resistance breeding. These findings provide useful genetic resources for developing resistant linseed cultivars to Fusarium wilt and contribute to sustainable disease management strategies to improve crop productivity in various agroecological settings.