Response of Chamecytisus palmensis to drought stress induced by polyethylene glycol during germination

Abstract

Seed germination and subsequent changes in Chamecytisus palmensis were studied under water limiting conditions, imposed by increasing concentrations of polyethylene glycol (PEG-6000) (0, 5, 10, 15, 20, 25, and 30%). Six water stress conditions (< −0.20, −0.20, −0.40, −0.60, −0.8, and −1.20 MPa) were created in the laboratory in a completely randomized design. The results showed that PEG-simulated drought stress had an inhibitory and lag effect on seed germination of C. palmensis. Seed germination was completely inhibited under the drought stress of 30% (−1.20 MPa). Similar to the seed germination, the growth of radicles and hypocotyls after seed germination was also restricted by PEG-simulated drought stress, especially when water potential was lower than −0.12 MPa (25%). In the same way, the ratio of radicles and hypocotyls significantly decreased with the increase of PEG concentrations, demonstrating strong adaptability to drought stress. Moreover, the decline of radicles and hypocotyls lead to a decrease in the number of root hairs. This would seriously affect the water absorption ability of the young roots. It was concluded that drought stress might be one of the causes for obstructed natural regeneration of C. palmensis plantations on sandy land.