Photosynthetic response of some Triticum cultivars to the combined influence of nanofertilizers and water deficit

The effects of water deficit modelling by polyethylene glycol (PEG), metal nanoparticles (NPs) and their combined action on water status, chlorophyll fluorescence and pigments composition in the leaves of three drought tolerant wheat genotypes - Triticum aestivum L. (Trypilska and Favorytka cultivars) and Triticum dicoccum Schrank. (cv. Holikovska), have been studied. Water deficit, induced by PEG, as well as the treatment with metal NPs (Cu, Fe, Mn, Zn) and their combined action, showed no effects on the maximal quantum yield of PSII photochemistry (Fv/Fm) in dark-adapted leaves of studied plants. However, water deficit decreased the efficiency of excitation energy capture by open PSII reaction centers (F-v'/F-m') in light-adapted leaves of the Favorytka cultivar. The increase of chlorophyll fluorescence photochemical quenching (qP) and actual quantum yield of PSII electron transport (phi PSII) levels, the decrease in non-photochemical quenching coefficient (qN) were observed in Favorytka and Holikovska cultivars under the combined action of water stress and NPs treatment. According to photosynthetic pigments composition, the NPs treatment of wheat plants, grown on medium with PEG, did not bear an additional pressure on the seedlings. However, the NPs treatment did not decrease the negative effect of the simulated water deficit of the cv. Favorytka seedlings.