Effect of short-term domestication on the tolerance of Oenanthe javanica to low-salt stress

In order to investigate the effects of low salt stress on the growth of watercress (Oenanthe javanica) and the effectiveness of short-term domestication in enhancing its salinity tolerance, the present study evaluated and compared the effects of low salt stress with salinity levels of 2, 4, 6, and 8 PSU (Practical salinity units) on the growth status and physiological and biochemical characteristics of domesticated and undomesticated watercress over a 54 d period. Effects. The watercress was domesticated under hydroponic conditions by increasing 2 PSU every 3 days. The results showed that after 54 d of stress, the short-term domesticated and non-domesticated watercresses could survive up to 6 PSU salinity, and the growth and biochemical processes of the watercresses were significantly affected by the difference in salinity and the short-term domestication. In terms of growth status, salt stress caused watercress fresh weight growth rate, leaf relative water content (RWC), chlorophyll (SPAD), and plant quality (total protein, vitamin C, and soluble polysaccharides) to decrease by more than 63.7%, 5.8%, 10.3%, and 13.4%, respectively, at a stress salt concentration exceeding 2 PSU, whereas domestication caused them to decrease by only 20.6%, 3.8%, 3.7%, and 2.1% or more; in terms of physiology and biochemistry, salt stress resulted in an increase in malondialdehyde (MDA), proline (Pro), reactive oxygen species (ROS), superoxide dismutase (SOD), peroxidase (POD), ascorbic acid peroxidase (APX), glutathione peroxidase (GSH-PX), and catalase (CAT), respectively, in watercress by 65.4%, 33.0%, 30.6%, 25.2%, 23.7%, 14.9%, 21.5% and 16.3%, respectively, whereas only 34.2%, 66.8%, 8.0%, 42.5%, 51.3%, 42.5%, 50.0% and 45.0%, respectively, were increased by domestication; Salt stress resulted in the decreases of K⁺/Na⁺ ratio in leaves and roots by 89.4% and Salt stress caused the K⁺/Na⁺ ratios of leaves and roots to decrease by more than 89.4% and 84.1%, respectively, whereas they only decreased by more than 64.8% and 60.6%, respectively, after domestication. In conclusion, low salt stress had different negative effects on the growth of watercress and its physiological and biochemical responses, but short-term domestication could reduce the negative effects.