Evaluating the Impact of Seed-Borne Mycoflora on Seed Quality and Health of Various Oryza sativa Varieties

Abstract

Seed mycoflora poses significant challenges to rice production, leading to substantial economic losses. Fourteen samples of stored and freshly harvested seeds of five rice varieties were collected from the Agricultural farm of Orissa University of Agriculture and Technology, Bhubaneswar, Odisha, to study the morphology of the mycoflora associated with rice seeds and their impact on seed health and quality. Eight fungal species, including Fusarium pallidoroseum, Fusarium fujikuroi, Curvularia lunata, Helminthosporium oryzae, Trichoconis padwickii, Aspergillus flavus, Rhizopus sp., and Penicillium sp., were isolated, identified, and morphologically characterized based on colony growth, mycelial features, conidial structures, and spore measurements. The rice varieties, viz., Hema, Jyotirmayee, Swarna, Lalat, and Annapurna, were artificially inoculated with F. pallidoroseum, F. fujikuroi, T. padwickii, C. lunata, and H. oryzae. Seeds showed that the fungi had a variable effect on seed quality parameters like germination, seedling vigor index I and seedling vigor index II, speed of germination, and seed health. A maximum of 16.33% reduction of germination was observed by T. padwickii, followed by F. fujikuroi (14.80% in Hema). Seedling vigor (1754.81) incited by T. padwickii inoculation was recorded to be the lowest. Seed rot up to 15.8% was observed in the case of F. fujikuroi. The percentage of root discoloration reached 40.0% by F. pallidoroseum and T. padwickii. In Jyotirmayee, C. lunata caused an 18.88% germination reduction and the lowest seedling vigor (1866.03) by T. padwickii. T padwickii also caused the highest reduction of seedling dry weight (36.12%) in this variety. The result reveals the diversity and prevalence of fungal pathogens in rice seeds. Hence, this study underscores the importance of seed sterilization practices in reducing fungal contamination and the requirement of thorough seed examination to reduce the effects of seed mycoflora associated with rice seeds, which could affect rice production.