Semo (Czechia)

Abstract The Multi-hollow Surface Dielectric Barrier Discharge (MSDBD) generated in ambient air at atmospheric pressure was used to treat maize, pea, wheat and parsley seeds. Plasma exposure was applied as a pre-treatment before the seeds coating with agrochemicals. The aim of this study was to decrease the dustiness of coated seeds using plasma pre-treatment. The optimization process of plasma treatment parameters for individual seed species consisted of choosing a suitable exposure time (20 s, 60 s) and airflow (10 L/min, 15 L/min). The plasma made the seeds' surface more hydrophilic; therefore, better agrochemicals adhesion was achieved on the seeds' surface. Wettability improvement was demonstrated via water uptake of seeds and apparent contact angle change. Ambient air plasma at a 15 L/min flow rate was measured using optical emission spectroscopy, and the values of vibrational (3000 K) and rotational (347 K) temperatures were obtained from spectra simulation. The surface temperature of the MSDBD ceramics plate was measured with a thermal camera for different gas flow rates and constant input power of 30 W because the temperature is crucial parameter for seed treatment. The surface morphology was not affected due to plasma treatment, even for a longer exposure time. A significant decrease in dustiness measured according to the Heubach method was achieved for pea (57.1%) and parsley (41.4%) seeds. A lower decrease in dustiness was registered in the case of wheat (14.6%) and maize (17%) seeds. The results showed that MSDBD plasma generated in the air at optimized conditions is able to decrease the coated seed dustiness regardless of seed type and size, while seeds germination and surface coverage percentage remained unchanged.

The paper presents the effects of plasma treatment on agricultural seeds. Cucumber and pepper seeds, widely used in agriculture, were treated using the Diffuse Coplanar Surface Barrier Discharge (DCSBD) at atmospheric pressure in ambient air. The plasma treatment (4 s for pepper, 20 s for cucumber) led to an improvement of germination and germinating power. XPS confirmed chemical changes on the seed surface. The surface morphology of the plasma treated seeds showed no evidence of structural damage. The conclusion is that DCSBD proves to be able to reduce some of the microorganisms and pathogens affecting the seeds. Thanks to their technical simplicity and easy scaling‐up, DCSBD plasma sources open new opportunities for atmospheric pressure plasma application in the agricultural industry.

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Abstract Forty‐one lettuce cultivars (butterhead type), carrying race‐specific resistance gene Dm11 in combination with some others, were studied for field resistance to Bremia lactucae. Significant differences in the level of field resistance were revealed. Most of the cultivars under study were highly susceptible under field conditions. There are evident relationships between combinations of race‐specific Dm genes and field resistance. The cultivars with gene combinations Dm2, Dm3 and Dm11 are susceptible. A very high level of field resistance was detected in the cultivars with combination of genes Dm5/8, Dm6 and Dm16 (cvs. ‘Celia’, ‘Katanga’ and ‘Musette’). This is in close link with their Lactuca serriola origin and a high level of field resistance in progenitors.