Influence of UV-C Irradiation Duration on Seed-Borne Fungal Suppression, Germination, and Seedling Development in Rice (Oryza sativa L.)

The present study was conducted to study the effect of exposure time to ultraviolet-C (UV-C) radiation on seed germination, fungal suppression and seedling growth of three Egyptian rice cultivars, namely, Sakha 105, Sakha 108, and Giza 183. Experiments were carried out under controlled laboratory conditions. Rice seeds were exposed to UV-C radiation with a wavelength of 253.7 nm and intensity of 1960 µW cm2 for 0 (control), 10, 20, 30, 40, 50, and 60 min. Initial seed health testing showed the presence of several seed-borne fungi, mainly Alternaria alternata, Rhizoctonia solani, and Fusarium verticillioides, in addition to Aspergillus niger and Aspergillus flavus. Results revealed that UV-C exposure time, rice cultivar and their interactions significantly (p < 0.05) affected germination percentage, reduction percentage of seed fungal infection, and seedling growth parameters. The optimum exposure time was 30 min, which was found to maximize germination and improve shoot and root growth to achieve high levels of fungal suppression. Giza 183 exhibited the highest average germination percentage (92.40%), while Sakha 105 obtained the highest shoot height (17.00 cm) and root length (12.91 cm). The results indicate that UV-C irradiation is an effective, residue-free and environmentally sustainable seed treatment technology for improving rice seed quality as well as early seedling performance.