The effect of strong microwave electric field radiation on: (2) wheat (Triticum aestivum L.) seed germination and sanitation

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 SW 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.