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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.
The Impact of Acetic Acid Treatments on Stored Onion (Allium cepa L.) Seeds’ Quality
The aim of the studies was to evaluate the effects of acetic acid treatments on the quality of stored onion seeds. Seeds of two samples were soaked for 30 min in 0.25, 0.5, 1 and 2% acetic acid solutions. Controls included untreated seeds, seeds soaked in distilled water and seeds treated with fungicide Zaprawa Nasienna T 75 WS/DS (a.i. 75% thiram). Germination, vigour and health of untreated and treated seeds were evaluated before and after 2, 6 and 12 months of storage at 4 and 20 °C. Treating onion seeds with acetic acid solutions, especially at the concentrations of 1 and 2%, reduced their infestation with Alternaria alternata, Botrytis cinerea, Cladosporium spp., Penicillium spp. and Stemphylium botryosum after storage at both temperatures. Seeds stored at 20 °C showed lower infestation with fungi than seeds stored at 4 °C. The acetic acid treatments did not have any adverse effect on germination and vigour of stored onion seeds. In some cases, the increase in germination at the first and final counts and the improvement in mean germination time were observed.
Grapefruit Extracts and Black Chokeberry Juice as Potential Antioxidant and Antifungal Agents for Carrot Seed Treatment
Grapefruit extracts and black chokeberry juice have antioxidant and antimicrobial properties. The aim of the experiment was to evaluate the effect of grapefruit-based preparations, Biosept Active and Citrogrep, and black chokeberry juice on the germination, vigor, and health of carrot seeds. The seeds of two cultivars were soaked for 30 min in 0.25% grapefruit-based preparations and in 5 and 25% chokeberry juice. Standard ISTA methods were used to evaluate seed germination and health. The chemical composition of the applied preparations and juice was analyzed with ultra-high-performance liquid chromatography electrospray ionization mass spectrometry. The grapefruit-based preparations differed significantly in their chemical composition, qualitatively and quantitatively, but in both of them, flavanones and flavones prevailed. Biosept Active improved seed germination especially in the cultivar, which was characterized by a lower initial seed quality. The significant positive correlations between germination at the first and final counts, as well as the contents of flavanones and flavones, were identified in this cultivar. Moreover, the negative correlations between the percentages of diseased seedlings, dead seeds, the percentages of seed infested with Cladosporium spp., Epicoccum nigrum, Melanospora simplex, and Ulocladium spp., and the investigated compounds were found. Chokeberry juice, at the higher concentration, showed some antioxidant activity; however, it frequently stimulated the growth of the fungi.
Effect of air temperature and relative humidity on the stored Welsh onion (Allium fistulosum L.) seeds
In the years 2018-2021, experiments on the effect of air temperature and relative humidity (RH) on the storage of Welsh onion (Allium fistulosum L.) seeds were carried out. Three different cultivars and one breeding line received from commercial plant breeding and seed production companies were used. All their seeds at the beginning of storage had high germination over 90%, and moisture content 7-8%. Then, they were stored for 30 months in the controlled conditions at 3 different temparatures: 7-8 °C, 10 °C and 25 °C, each with 2 different air relative humidty (RH): 25% or 45%. During the experiment, their quality was evaluated by germination test according to the International Seed Testing Association (ISTA) protocol. Additionally, after 1 and 2 years of storage at 7-8 °C and 25% air RH, the seeds of the line were evaluated for their incidence of fungi. It was found out that seeds of the tested genotypes kept good germination at 7-8 °C and at 10 °C, i.e. after storing them, the same effect was achieved. Thus, the latter can effectively lower the costs of the seed storage in commercial seed trade of the crop. The electric current consumption for the seeds stored at 7-8 °C in comparison with 10 °C was higher by 11.2%. In seeds of 3 genotypes, after storing them for 30 months, their germination was better at the air RH 45% than at 25%. Generally, low temperature (7-8 °C) favoured growth of Penicillium spp. and Phoma spp. on Welsh onion seeds during 2 years of storage, while storing at higher temperature (25 °C) resulted in the increase in seed infestation with Cladosporium spp. and Fusarium spp. The results obtained from this research can be used as a guideline for the storage in climatic and RH controlled chambers of all genotypes belonging to Allium fistulosum species, with the aim to maintain its seed germination quality related to the duration of the storage and taking into consideration the operating energy costs.