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.

Purpose: Molecular mechanisms underlying hyperthermia-induced cellular injury are not fully understood. The aim of this study was to identify the components of mitochondrial oxidative phosphorylation affected by mild hyperthermia and to quantify the contribution of each component to changes in system behaviour. Methods: Temperature effects on the oxidative phosphorylation in isolated rat-heart mitochondria were assessed using modular kinetic analysis. Mitochondrial H₂O₂ production and lipid peroxidation were measured for estimation of temperature-induced oxidative damage. Results: The increase of temperature in the febrile range (40°C) slightly activated mitochondrial function through stimulation of the respiratory module, without affecting the kinetics of the proton leak and phosphorylation modules. At 42°C, state 3 respiration rate remained unchanged, the proton leak across the inner mitochondrial membrane was substantially increased, the respiratory module slightly inhibited, leading to decreased membrane potential (Δψ) and diminished ATP synthesis (16% lower phosphorylation flux). Increase of temperature above 42°C caused dissipation of Δψ and abolishment of ATP synthesis indicating complete uncoupling of oxidative phosphorylation. The changes in mitochondrial functions induced by incubation at 42°C were completely reversible in contrast to only partial recovery after incubation at higher temperature (45°C). Furthermore, hyperthermia stimulated the production of H₂O₂ and membrane lipid peroxidation with maximal rates observed at 40°C. Conclusions: We demonstrated for the first time that febrile temperature (40°C) activates mitochondrial energy supplying functions, whereas further temperature increase by only a few degrees leads to severe impairment of mitochondrial ability to maintain ΔΨ and synthesise ATP.

Stimulation of mitochondrial respiration by physiological concentrations of Ca²⁺ was studied to determine which components of oxidative phosphorylation are affected by Ca²⁺. The kinetic dependence of the respiratory chain, phosphorylation subsystem and proton leak on the mitochondrial membrane potential in isolated rat heart mitochondria respiring on 2-oxoglutarate or succinate was measured at two different concentrations of external free Ca²⁺. The results show that proton leak is not directly affected by Ca²⁺, but that both the respiratory and phosphorylation systems can be directly stimulated by Ca²⁺ depending on conditions. Although Ca²⁺ directly stimulates the phosphorylation system, this has relatively little effect on respiration rate with 2-oxoglutarate in States 3 and 4 because the subsystem has little control over respiration. However, in intermediate states, the phosphorylation system has greater control and Ca²⁺ stimulation of this system contributes substantially to the stimulation of respiration and phosphorylation. In the case of succinate oxidation neither the respiratory subsystem nor the phosphorylation system is stimulated by Ca²⁺.