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.

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.

This study compared the effects of seed treatment with low-pressure cold plasma (CP) and atmospheric dielectric barrier discharge (DBD) plasma on morpho-biochemical traits in Stevia rabaudiana Bertoni plants cultivated by two methods: in soil and aeroponics. We investigated the impact of the treatments on the germination, plant growth, and content of secondary metabolites, namely steviol glycosides (SGs), rebaudioside A (RebA), and stevioside (Stev), as well as phenolic compounds and flavonoids. Seeds were treated for 2, 5, and 7 min with CP or DBD and 5 min with vacuum six days before sowing. All growth parameters in aeroponics exceeded the parameters of seedlings in the corresponding groups cultivated in soil. Seed treatments stimulated SGs biosynthesis in seedlings grown in soil, except for CP7. Although there were no stimulating effects of seed treatments on SGs in aeroponics, overall SG concentrations were considerably higher compared to plants cultivated in soil: the RebA+Stev concentration was 1.8–2-fold higher in the control, V5-, and CP-treated groups, and 1.3-fold higher in the DBD5 and DBD7 groups. Thus, aeroponic cultivation has the potential to improve the growth and synthesis of SGs in stevia, while a combination of aeroponics with seed treatments only increases the content of antioxidants and antioxidant activity.

Aeroponic plant cultivation is a novel technology explored for its potential in indoor farming. In this study, we evaluated the effects of seed treatments with cold plasma on growth, physiological processes, and biochemical parameters in two lettuce cultivars—green variety ‘Perl Gem’ and red variety ‘Cervanek’ cultivated in an aeroponic system for 45 days. Seeds were treated with low-pressure air plasma for 3 min (further denoted as LCP3) or atmospheric dielectric barrier discharge (DBD plasma) for 3 and 5 min (referred to as DBD3 and DBD5 groups). We estimated the effects of seed treatments on parameters of seedling growth, photosynthetic efficiency, amounts of photosynthetic pigments, anthocyanins, total phenolic compounds (TPC), and antioxidant activity in leaves. Despite the observed effects on germination and early growth, seed treatments did not affect biomass gain or head/root ratio in both lettuce cultivars. Seed treatments increased the photosynthetic performance index and amounts of photosynthetic pigments in ‘Pearl Gem’ but not ‘Cervanek’ leaves. Seed treatments enhanced the content of protective phenolic compounds and antioxidant activity in ‘Pearl Gem’, and anthocyanin content in ‘Cervanek’ leaves, indicating potential to improve the nutritional value of the edible part of lettuce cultivated in an aeroponic system.

Seed processing effects induced by two types of cold plasma, CP (low-pressure plasma, LCP; dielectric barrier discharge plasma, DBD), and vacuum (V) treatments were compared by estimating changes in the emergence and growth of lavender seedlings, the density of leaf trichomes, and the biochemical composition of leaf extracts, including the content of photosynthetic pigments, TPC, antioxidant activity, and the amounts of two hydroxycinnamic acids associated with antioxidant activity—chlorogenic and rosmarinic acid. DBD treatment for 3 min stimulated the emergence and growth of seedlings but induced negative or neutral effects on biochemical parameters. All treatments, except DBD3, increased the density of glandular trichomes in leaves. Short-term treatments with LCP (0.5 min), DBD (2 min), and V (2 min) increased the total phenolic compound (TPC) content by 15–25%, and the first two treatments enhanced antioxidant activity (21–32%). HPLC analysis revealed that V (2 min) treatment was the most effective, increasing the content of chlorogenic (49%) and rosmarinic (14%) acid. LCP (1 min) and DBD (2 min) treatments increased chlorogenic acid content by 9% and 26%, respectively. The obtained results support the potential of pre-sowing seed treatments with CP and vacuum to produce raw lavender material enriched by biologically active compounds for pharmaceutical and nutraceutical applications.