The effects of Norway spruce (Picea abies) seed treatment with cold plasma (CP), vacuum, and electromagnetic field (EMF) on germination and seedling growth are studied. CP treatments negatively affected germination ‘in vitro’, but for germination in cassettes CP (7 min) and EMF (5 min) significantly increased the germination yield. All treatments increase the germination rate in cassettes except CP (7 min) treatment having a negative effect. Seed treatment with CP and EMF increases the number of paramagnetic centers in dry seeds and modulate H2O2 production in germinating seeds. After the second vegetation season seedlings grown from CP (5 min) and CP (7 min) treated seeds, characterized by negative effects on either the germination rate or yield, have 50–60% larger height and 40–50% increased branching in comparison to the control seedlings.

The effects of seed treatment with cold plasma (2–7 min), vacuum (7 min), and electromagnetic field (5–15 min) on Echinacea purpurea germination and performance are studied. All treatments induce faster germination but did not change the final germination percentage, except the decrease evoked by vacuum treatment. The plants grown from all groups of treated seeds have larger height, develop more leaves, some treatments increase root weight. The content of vitamin C and phenolic acids in extracts of plant leaves from the treated groups is substantially higher in comparison to the control, so that the amount of cichoric acid per plant increased up to 3.8‐fold, and amount of vitamin C per plant – up to 1.9‐fold. Seed treatments induce large increase in radical scavenging activity (up to 114%) in leaf extracts.

Radiofrequency (5.28 MHz) electromagnetic radiation and low-temperature plasma were applied as short-term (2-15 min) seed treatments to two perennial woody plant species, including Smirnov's rhododendron (Rhododendron smirnowii Trautv.) and black mulberry (Morus nigra L.). Potential effects were evaluated using germination indices and morphometry. The results suggest that treatment with electromagnetic field stimulated germination of freshly harvested R. smirnowii seeds (increased germination percentage up to 70%), but reduced germination of fresh M. nigra seeds (by 24%). Treatment with low-temperature plasma negatively affected germination for R. smirnowii, and positively for M. nigra. The treatment-induced changes in germination depended on seed dormancy state. Longer-term observations revealed that the effects persisted for more than a year; however, even negative effects on germination came out as positive effects on plant morphometric traits over time. Treatments characterized as distressful based on changes in germination and seedling length increased growth of R. smirnowii after 13 months. Specific changes included stem and root branching, as well as increased leaf count and surface area. These findings imply that longer-term patterns of response to seed stressors may be complex, and therefore, commonly used stressor-effects estimates, such as germination rate or seedling morphology, may be insufficient for qualifying stress response. Bioelectromagnetics. 37:536-548, 2016. © 2016 Wiley Periodicals, Inc.

Pre-sowing treatment of red clover seeds with cold plasma (CP) and electromagnetic field (EMF) was applied aiming to evaluate changes induced in germination and early seedling growth under controlled laboratory conditions, and to estimate treatment effects on plant growth, biomass production, nutritional value and the amounts of major leaf secondary metabolites under long-term field experimental conditions. The effects of seed treatment using radio-frequency EMF (5, 10, 15 min) and CP (2, 5, and 7 min) on seed germination kinetics, morphometric parameters of seedlings were assessed for two cultivars of red clover—‘Vyčiai’ and ‘Sadūnai’. Long-term observations revealed that the effects of seed treatments persist for the entire vegetation season, while the observed effects on germination (CP increased germination rate by 4%–20%) do not provide sufficient information to predict the impact on plants on a longer time scale. The effects on morphometric parameters were dependent on plant cultivar, and were much stronger (up to 24% for ‘Sadūnai’ and 49% for ‘Vyčiai’) after growing the plants in the field for 5 months in comparison to the effects (absent or below 10%) observed in the early growth stages. A minor improvement of nutritional value per biomass unit was observed for ‘Vyčiai’. Protein yield per plant increased substantially (up to 70%). Pre-sowing seed treatment with CP and EMF had an obvious impact on the amounts of major isoflavones in leaves, and the nature of these changes strongly depended on the vegetation stage of plants (before flowering or at flowering stage). CP treatment for 5 min was found to be the most effective in this respect in not flowering plants, inducing a strong increase in biochanin A/formononetin ratio in leaves of both cultivars. However, an opposite effect was observed in the flowering plants, where the CP and EMF treatments decreased biochanin A/formononetin ratio.

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.