Enhancing Zinnia (Zinnia elegans Jacq.) Seed Quality through Microwaves Application

In organic farming, microwave irradiation can be used as an alternative to standard chemical seed treatment. The increase in temperature during this treatment may negatively affect the germination of low-quality seeds. The aim of the study was to evaluate the effect of microwaves on germination and the health of zinnia seeds using four seed samples varying in initial seed quality. Seeds were placed in a beaker with distilled water and irradiated at power output levels of 500, 650 and 750 W for 30, 35, 40, 45 and 50 s. Controls were untreated seeds, seeds treated with fungicide and seeds soaked in water for 30, 35, 40, 45 and 50 s. Germination and health tests were performed for controls and microwave-treated seeds. Analyzed samples differed in seed quality and response to microwave irradiation. Improvement in seed germination after microwave treatment was observed in three of the tested samples. The fungi Alternaria alternata, A. zinniae and Fusarium spp. prevailed on the seeds. Microwave treatment, especially at power outputs of 650 and 750 W, usually positively affected seed health, significantly increasing the number of seeds free of fungi, but when water temperature during treatment exceeded 60 °C significant deterioration in germination parameters was observed in all tested samples.