Elevated CO2 improves the growth of grapevine young plants under salinity favoring ionic homeostasis and decreasing oxidative damages

Abstract

Abstract This study tested the hypothesis that elevated CO2 improves the growth of grapevine seedlings, achieving greater vigor and shortening the production time under salinity due to the best ionic homeostasis and oxidative protection. Seedlings were exposed to isolate and combined effects of CO2 (ambient – 400 and elevated – 800 µmol mol− 1) and salinity (absence – 0 and presence – 80 mM NaCl) in a growth chamber. In these conditions, two-old-month grapevine (Vitis ssp.) plants were grown and defoliated after 20 days, followed by more than 60 days of growth to the emission of new shoots (buds, leaves, and stems). Salinity delays and decreases the emission of new shoots, while elevated CO2 improves the growth of new shoots. Elevated CO2 promoted the leaf dry matter (DM) contends and shoot/root ratio in the absence and presence of salt, and the partial recovery of losses leaf DM under salt. High CO2 mitigated ionic toxicity under salt stress through lower leaf Cl− and Na+ accumulation with a preferential allocation of these ions in stems and roots, relative to plants under salt alone. Elevated CO2 stimulated the K+ content in the whole plant (leaves/stems/roots), in salt absence and presence, with increases for K+/Na+ ratios in leaves and roots under salinity. High CO2 favored the water potential (ΨW) reduction under salinity and increase water relative content (RWC) of plants under two salt levels. Under salt absence, photochemical efficiency indicators quenching photochemical (qP), electron transport rate (ETR), and non-photochemical quenching (NPQ) showed that photosynthesis was significantly favored by high CO2 and the effect was also important for mitigating the salt impact for CO2 uptake. Taken together, data show that elevated CO2 has the potential to improve grapevine seedlings’ production system, mainly under salt stress.