Physiological responses of the invasive great yellowcress (Rorippa amphibia (L.) Besserd) under different water conditions.
The invasion plant Rorippa amphibia (L.) Besser native to Europe was first reported in China in 2009 and then it spread extensively in Liaoning Province. It natively grows in flooded or shallow habitats, but it actually appears in more broadly water-related habitats in Shenyang, Liaoning Province. Individuals of Rorippa amphibia were treated for 1 month under 4 water gradients with waterlogging, wet, moderate (CK) and drought in Shenyang Normal University, and their physiological indexes were measured. The results showed water stresses had some adverse effects on its physiological processes including the significantly decreasing of the transpiration rate, net photosynthetic rate and stomatal conductance, the increasing of malondialdehyde and electrolyte leakage. But the change of other physiological indexes as follows may alleviate the disadvantageous effects of water stresses. Compared with the CK, the chlorophyll content increased significantly, especially under the drought treatment. The activities of SOD, POD and CAT increased. SOD and POD activities were highest under the drought treatment and CAT activity was highest under the waterlogging treatment. The osmotic adjustment substance contents including proline, soluble protein and soluble sugar were significantly increased under water stresses, especially under the drought treatment and the waterlogging treatment. The root activities increased as soil water content declined and the activity under the drought treatment was significantly higher than the other 3 treatments. The result that all the individuals of Rorippa amphibia could survive under extreme soil water conditions meant that Rorippa amphibia had a strong invasive line because it could adapt to very different soil water conditions from waterlogging to extremely drought condition.