Effects of selenomethionine on the antioxidative enzymes, water physiology and fruit quality of strawberry plants under drought stress

To investigate the role of selenomethionine (SeMet) in regulating the drought tolerance of strawberry plants, we explored the effects of SeMet on the antioxidative enzymes, water physiology and fruit quality of the strawberry plants under drought stress (DS). In this study, we used the strawberry variety 'Sweet Charlie' as the material and investigated the effects of SeMet on the drought tolerance of the strawberry plants through foliar spraying and pot experiments. The results showed that the DS obviously enhanced the activities of the antioxidant enzymes (ascorbate peroxidase, superoxide dismutase, peroxidase and catalase) and increased the malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents in the leaves of the strawberry plants, compared with the control. Meanwhile, the DS markedly improved the fruit quality parameters of the soluble solids (SS), soluble sugar, vitamin C (Vc) and sugar-acid ratio. Compared with the DS alone, SeMet obviously enhanced the activities of the above antioxidant enzymes in the leaves and fruit quality parameters of SS, sugar-acid ratio and the soluble sugar and Vc contents, but decreased the MDA and H2O2 levels in the strawberry leaves under the DS. However, the DS markedly decreased the photosynthetic pigment chlorophyll (Chl) and carotenoid (Car) contents, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), relative water content (RWC), fruit weight and plant height and biomass. Compared with the DS alone, SeMet significantly increased the Chl and Car contents, Pn, Tr, Gs, RWC, fruit weight and plant height and biomass. Meanwhile, SeMet al.ne decreased the MDA and H2O2 levels and improved the other indicators except for the RWC compared with the control. Our present results concluded that SeMet relieved the adverse impacts of DS on the strawberry growth by enhancing the antioxidant enzymes, photosynthesis and water conditions of the leaves, which promoted the fruit weight and quality. Thus, SeMet can be considered as a regulator to improve the drought tolerance and fruit weight and quality of strawberries.