The effect of high power microwave (HPM) irradiation on seed germination and seedlings was evaluated. Vegetable seeds were subjected to HPM irradiation. The main focus was on the thermal heating elimination during seeds irradiation. For that reason short high frequency microwave pulses were used. The study object was seeds of different harvest years (2000, 2003 and 2008) of radish (Raphanus sativus L.) variety 'Babtų žara', tomato (Lycopersicon esculentum Mill.) variety 'Viltis', carrot (Daucus sativus Rohl.) variety 'Vaiguva' and tomato (Lycopersicon esculentum Mill.) variety 'Red Cherry' (seeds harvested in 1980). In the first experiment, all seeds were exposed to microwaves at 9.3 GHz frequency for 10 min. In the second experiment, carrots 'Vaiguva' seeds (11 years-old) were exposed to microwaves at 9.3 GHz frequency for 5 and 20 min and exposed to 2.6 and 5.7 GHz microwaves for 10 min. To establish microwave effect on seedling growth rate, tomato, carrot and radish seeds harvested in 2008 were exposed to microwaves at 9.3 GHz frequency for 10 min. It was established that 11 year-old radish seeds exposed to 9.3 GHz microwaves had higher germination as compared with non-irradiated seeds. HPM increased radish germination energy by 6% in seeds harvested in 2003. HPM exposure significantly increased the germination energy and germination of 8 year-old carrot seeds. The highest carrot seed germination was established at 9.3 GHz microwave frequency under 5 min exposure. Seed exposure to HPM (9.3 GHz) had a significant positive effect on dry weight of tomato seedling shoots and on tomato and radish seedling height, but it had negative influence on carrot seedling height. Seed irradiation with HPM (9.3 GHz) had a significant positive effect on the amount of chlorophyll a, chlorophyll b, chlorophylls a + b and carotenoids in tomato seedlings' fresh mass, but the opposite effect was determined in carrot seedlings' fresh mass.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

The seeds of the winter and spring wheat (Triticum aestivum L.) were subjected to a strong microwave electric field (SMEF) generated in a high power magnetron generator, working in a pulsed mode. Seed samples with different moisture contents (12, 15 and 18 %) were treated at the band 2.6, 5.7 and 9.3 GHz at 5, 10 and 20-minute exposures. Seed germination energy (GE), germination (G), abnormally germinated seeds (AG), germination index (GI) and seedling vigour index (SVI) were tested. The effect of SMEF on Tilletia caries infestation, plant productivity and seed sanitation was also explored. Seed treatment with SMEF did not sufficiently effect on winter wheat seed GE and G; however, the increase in AG and reduction in GI and SVI were observed. The negative effect on GI and SVI increased when seeds with higher humidity were treated. Treatment of winter wheat cv. 'Kovas' seeds, artificially inoculated with Tilletia caries, with SMEF showed a trend towards reduction of bunt infected ears. Seed treatment with SMEF stimulated grain yield increase and the bands 2.6 GHz for 20 min, 5.7 GHz for 10 min and 9.3 GHz for 5 and 10 min induced an increase in grain number and grain weight per ear. The efficacy of the chosen SMEF bands and exposition time on winter and spring wheat seed sanitation were contradictory. The SMEF treatment against wheat seed borne pathogens such as Phaeosphaeria nodorum (causal agent of Stagonospora glume blotch), Pyrenophora tritici-repentis (causal agent of tan spot) and Fusarium spp. (causal agents of seedling and adult plant foot and root rots and Fusarium head blight) gave conflicting and inconsistent efficacy results. The composition of most frequently isolated Fusarium species on SMEF treated winter wheat seeds was pertained to SMEF bands and exposition time.