Effects of simulated drought stress on the growth and physiological and biochemical parameters of Paspalum wettsteinii

Since global drought events have been occurring more frequently, identification of the key mechanisms underlying adaptive responsiveness to drought stress is urgently needed to improve the drought resistance of plants. In this study, a simulated drought stress experiment (five gradients (0, - 0.1, - 0.3, - 0.5, and - 0.7 MPa) x four exposure times (7, 14, 21, and 28 days)) was performed to study the growth, photosynthesis and physio-biochemical parameters of Paspalum wettsteinii. The results indicate that mild drought stress (- 0.1 MPa) significantly increased the growth, photosynthesis, antioxidant (superoxide dismutase, catalase, and peroxidase), and osmotic adjustment (proline, soluble sugar, and soluble protein contents) capacities. In contrast, extreme drought stress (- 0.7 MPa) markedly decreased the growth, photosynthesis, antioxidant, and osmotic adjustment capacities but increased the intercellular CO2 concentration and malondialdehyde capacity. The responses to moderate (- 0.3 MPa) and severe (- 0.5 MPa) drought stress depended on the exposure time. Short-term drought stress promoted photosynthesis and increased the antioxidant and osmotic adjustment capacities, but these parameters were inhibited with increases in the exposure time. Overall, these findings highlight that the increases in photosynthesis, antioxidant and osmotic adjustment capacities and the decrease in lipid peroxidation capacity contribute to the adaptation of P. wettsteinii to drought stress. This study provides new insight into the adaptive responsiveness of P. wettsteinii to drought stress.