Soil alkalinization and salinization have increased worldwide due to extreme and/or prolonged drought periods as well as insufficient irrigation. Since crops generally react to soil salinity and high pH with decreased yield, the cultivation of tolerant biomass plants represents a reasonable alternative. Thus, we aimed to characterize the tolerance of the biomass plant Arundo donax to alkaline salt stress, induced by irrigation water containing NaHCO₃ and Na₂CO₃ mixture (1:1) at 80 mM and 200 mM of final concentration and pH 10. In terms of physiological parameters such as transpiration, chlorophyll content, photosystem II quantum efficiency, relative water content, and water saturation, the plants were resistant to the stress treatment. The negative impact on the water regime was only measured at 200 mM salt. The K/Na ratio decreased in parallel with Na accumulation. Plants also accumulated Zn, whereas a decrease in the concentration of most other elements (Ca, Cu, K, Mg, Ni, S, Si, and Sr) was detected. Antioxidative defence directed by multiple symplastic enzymes contributed to the high physiological tolerance to the applied stress. In conclusion, the cultivation of Arundo donax as a biomass crop appears to be a feasible alternative in areas affected by salinity or alkaline salt accumulation.

S-methylmethionine (SMM) is a universal metabolite of higher plants derived from L-methionine that has an approved priming effect under different types of abiotic and biotic stresses. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1) is a biomass plant increasingly applied in phytoremediation to stabilize or extract heavy metals. In this study, Szarvasi-1 was grown in a nutrient solution. As a priming agent, SMM was applied in 0.02, 0.05 and 0.1 mM concentrations prior to 0.01 mM Cd addition. The growth and physiological parameters, as well as the accumulation pattern of Cd and essential mineral nutrients, were investigated. Cd exposure decreased the root and shoot growth, chlorophyll concentration, stomatal conductance, photosystem II function and increased the carotenoid content. Except for stomatal conductance, SMM priming had a positive effect on these parameters compared to Cd treatment without priming. In addition, it decreased the translocation and accumulation of Cd. Cd treatment decreased K, Mg, Mn, Zn and P in the roots, and K, S, Cu and Zn in the shoots compared to the untreated control. SMM priming changed the pattern of nutrient uptake, of which Fe showed characteristic accumulation in the roots in response to increasing SMM concentrations. We have concluded that SMM priming exerts a positive effect on Cd-stressed Szarvasi-1 plants, which retained their physiological performance and growth. This ameliorative effect is suggested to be based on, at least partly, the lower root-to-shoot Cd translocation by the upregulated Fe uptake and transport.