Exogenous calcium enhances the physiological status and photosynthetic capacity of rose under drought stress

Drought (water shortage) can substantially limit the yield and economic value of rose plants (Rosa spp.). Here, we characterized the effect of exogenous calcium (Ca2+) on the antioxidant system and photosynthesis-related properties of rose under polyethylene glycol 6000 (PEG6000)-induced drought stress. Chlorophyll levels, as well as leaf and root biomass, were significantly reduced by drought; drought also had a major effect on the enzymatic antioxidant system and increased concentrations of reactive oxygen species. Application of exogenous Ca2+ increased the net photosynthetic rate and stomatal conductance of leaves, enhanced water-use efficiency, and increased the length and width of stomata following exposure to drought. Organ-specific physiological responses were observed under different concentrations of Ca2+. Application of 5 mmol · L-1 Ca2+ promoted photosynthesis and antioxidant activity in the leaves, and application of 10 mmol · L-1 Ca2+ promoted antioxidant activity in the roots. Application of exogenous Ca2+ greatly enhanced the phenotype and photosynthetic capacity of potted rose plants following exposure to drought stress. Overall, our findings indicate that the application of exogenous Ca2+ enhances the drought resistance of roses by promoting physiological adaptation and that it could be used to aid the cultivation of rose plants.