The effect of pre-sowing plasma seed treatment of maize ( Zea mays L.), narrow-leaved lupine ( Lupinus angustifolius L.) and winter wheat ( Triticum aestivum L.) on seed germination, plant resistance to common diseases during vegetation and crop yield is studied in laboratory and field experiments. It is shown the efficiency of seed treatment by low-pressure radio frequency plasma in suppression of a number of fungal crop diseases such as boil smut of maize, root rot of lupine and winter wheat at different growth stages. At the stage of V9 (9th leaf visible) the infection level in maize plants from treated seeds was 3 times less than that in control. Root rot disease development of lupine at the first stages (3rd–4th leaves emerged) of growth did not exceed 6.9% in plants from the treated seeds while reached to 47.8% in control. Pre-sowing seed treatment led to suppress the anthracnose spreading on narrow-leaved lupine up to the flowering stage. It was revealed that, due to a decrease in the level of seed infection, stimulation of field germination, early seedling growth and plant resistance to pathogens during the vegetation period, the winter wheat grain yield increased by 2.3%, maize—by 1.7%, narrow–leaved lupine—by 26.8% compared to control plants. Increases in activity of non-enzymatic antioxidants (proline, anthocyanins as well as total phenolic content) in roots of maize seedling were observed which may indicate a significant role of plasma seed treatment in improving the plant resistance to biotic and abiotic stress during the vegetation.

The aim of this study was to determine the effects of pre-sowing seed treatment with cold plasma (CP) and an electromagnetic field (EMF) on the agricultural performance of two cultivars of common buckwheat (Fagopyrum esculentum Moench)—‘VB Vokiai’ and ‘VB Nojai’. For this, the effects of CP and EMF on seed germination, plant growth in the field, photosynthetic efficiency, biomass production, seed yield, and the amount of secondary metabolites and minerals in the harvested seeds were estimated. Although the percentage of seedlings that emerged under field conditions decreased by 11–20%, seed treatments strongly improved buckwheat growth and yield. Irrespective of differences in the dynamics of changes in the growth and photosynthetic activity between the two cultivars, the weight of seeds collected per plant for both cultivars was significantly higher (up to 70–97%) compared to the control. The biochemical composition of the harvested seeds (Fe, Zn, quercetin content) was also altered by seed treatments. Thus, pre-sowing treatment of buckwheat seeds with CP and EMF substantially stimulated plant growth in the field, increased biomass production, seed yield and nutritional quality. The results obtained strongly support the idea that plant seed treatment with physical stressors has great potential for use in agriculture.

Stevioside (Stev) and rebaudioside A (RebA) are the most abundant steviol glycosides (SGs) responsible for the sweetness of Stevia rabaudiana Bertoni. As compared to Stev, RebA has a higher sweetening potency, better taste and therefore is the most preferred component of the stevia leaf extracts. The aim of this study was to determine the effect of pre-sowing seed treatment with abiotic stressors cold plasma (CP) and electromagnetic field (EMF) on the amount and ratio of RebA and Stev in the leaves of stevia. Additionally, the effect on total phenolic content, flavonoid content and antioxidant activity was investigated. Seeds were treated 5 and 7 min with cold plasma (CP5 and CP7 groups) and 10 min with electromagnetic field (EMF10 group) six days before sowing. The germination tests in vitro demonstrated that all treatments slightly increased germination rate and percentage. HPLC analysis revealed that CP and EMF had strong stimulating effect on SGs accumulation. All treatments increased RebA concentration approximately 1.6-fold; however, the ratio of RebA/Stev decreased from 8.5 in the control to 1.9, 2.5 and 1.1 in CP5, CP7 and EMF10 groups respectively, since the concentration of Stev increased more than RebA, 7.1, 4.6 and 11.0-fold, respectively, compared to control. However, treatments had opposite effect on total phenolic content, flavonoid content, and antioxidant activity. We have demonstrated for the first time that short time pre-sowing treatment of stevia seeds with CP and EMF can be a powerful tool for the enhancement of biosynthesis of RebA and Stev, however it can have negative impact on the content of other secondary metabolites.

This study aimed to estimate the effects of cold plasma (CP) and electromagnetic field (EMF) treatment of red clover (Trifolium pratense) seeds with different coat colors on germination kinetics, the content of seed phytohormones, and the growth of seedlings. Seeds of red clover cultivar ‘Arimaiciai’ were treated with radio-frequency EMF or capacitively coupled low-pressure CP for different durations. There were no differences in germination kinetics between yellow, brown, and dark purple seeds in control, but the germination rate of seeds treated with CP and EMF depended on seed color: The germination of yellow seeds was stimulated stronger compared to dark purple and brown seeds, and EMF did not stimulate germination in brown seeds. The content of phytohormones in control seeds and the shift in their amount induced by seed treatments were also strongly dependent on seed color. No relationship was found between the effect on germination kinetics and changes in phytohormone levels. In the control, seedlings growing from the yellow seeds were heavier, and the number of root nodules was 12.5 times larger compared to seedlings of dark purple seeds. Seed treatments with CP and EMF significantly increased the number of root nodules, and this effect was stronger in seedlings from dark purple seeds compared to those from yellow seeds.

In this study, the effects of seed treatments with different stressors, such as cold plasma (CP), a vacuum and an electromagnetic field (EMF), on the in vitro germination of industrial hemp cv. Futura 75 were compared with the effects on germination in the field, plant growth, and the amount of major cannabinoids in the leaves and inflorescences of female plants. CP and EMF (but not vacuum) treatments improved in vitro seed germination, but had no impact on germination in the field. EMF treatment increased the weight of the above-ground part of male and female plants grown for 4 months by 65–70% and the number of female inflorescences by 70%. CP stimulated the growth of male plants (weight increased 1.4 times) but reduced the growth of female plants. Vacuum treatment did not induce changes in the growth of female and male plants. Vacuum and EMF treatments did not change the amount of cannabidiolic acid (CBDA), but CP decreased the CBDA content in hemp leaves by 41%. Vacuum treatment increased the amount of CBDA in female plant inflorescences by 26%. Thus, hemp seed treatment with EMF has a potential application for increasing the biomass of female plants. CP treatment can be used to increase male plant production while vacuum treatment can stimulate CBD production.

Исследованы физиолого-биохимические параметры проростков кукурузы после выдерживания семян, предварительно подвергнутых кратковременному воздействию высокочастотного (ВЧ) электромагнитного поля (ЭМП) и плазмы ВЧ разряда, в контролируемых оптимальных и неблагоприятных условиях хранения. При оптимальных условиях хранения предварительная обработка семян плазмой и ЭМП стимулировала рост и развитие проростков, содержание пролина соответствовало таковому у необработанных семян (оптимальный контроль) или несколько снижалось, общая активность пероксидазы увеличивалась. Ускоренное старение контрольных семян в течение 3 сут (стрессовый контроль) вызвало повышение электропроводности их экссудатов и замедление роста проростков на фоне увеличения содержания пролина и усиления пероксидазной активности. В экспериментальной группе с предварительной обработкой семян ЭМП исследуемые показатели сохранялись на уровне оптимального контроля, хотя пероксидазная активность была выше, чем у проростков из оптимального и стрессового контроля. У проростков, выросших из обработанных плазмой семян, наряду с замедлением роста отмечалось сохранение высокой пероксидазной активности и увеличение накопления пролина. В результате ускоренного старения в течение 7 сут всхожесть семян, обработанных плазмой, снижалась практически в 2 раза, значительно тормозилось прорастание, наблюдалось ингибирование активности пероксидазы в клетках корней. Содержание пролина в обработанных ЭМП образцах возросло на 51,8 %, а в обработанных плазмой – в 3 раза по сравнению с оптимальным контролем. Так как уровень пролина возрастает пропорционально увеличению степени и продолжительности воздействия неблагоприятных условий хранения, предполагается, что его накопление в проростках свидетельствует скорее о степени воздействия повреждающего фактора, а не о проявлении устойчивости к нему. Анализ эффективности различных режимов предпосевной обработки семян кукурузы показал, что воздействие ВЧ ЭМП на эту культуру может выступать индуктором повышения резистентности организма, обеспечивая сохранение физиологического качества семян при хранении и поддержание скорости роста растений или их выживание.