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

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, this study evaluated and compared the impact of low salt stress with salinity levels of 2, 4, 6, and 8 Practical salinity units PSU) and short-term domestication on salinity tolerance, growth, and physiological and biochemical characteristics of domesticated and undomesticated watercress over a 54 d period. The watercress was domesticated under hydroponic conditions by incrementally increasing the salinity by 2 PSU every 3 d. The results exhibited that After 54 d of stress, both the short-term domesticated and non-domesticated watercress survived up to 6 PSU salinity. Salinity and short-term domestication significantly affected watercress growth and biochemical processes of watercress. At the salt stress concentration of more than 2 PSU, in terms of growth status, the growth rate of fresh weight, the growth rate of leaf relative water content (RWC), the growth rate of chlorophyll (SPAD) and the plant quality (total protein, vitamin C and soluble polysaccharides) decreased by more than 63.7%, 5.8%, 20.2% and 13.4%, respectively, whereas they decreased by more than 20.6%, 3.8%, 7.2% and 2.1%, respectively, after the domestication of watercress, 3.8%, 7.2% and 2.1%, respectively. In terms of physiology and biochemistry, the percentages of increase in malondialdehyde (MDA) and proline (Pro) content in watercress leaves were higher than 65.4% and 33.0%, respectively, due to salt stress, while they were only higher than 34.2% and 66.8%, respectively, after the domestication; the percentage of increase in reactive oxygen species (ROS) in watercress leaves was higher than 20.6% due to salt stress, but was only higher than 8.0% after domestication; the percentage of increase in reactive oxygen species (ROS) was higher than 20.6%, while it was only higher than 8.0%, and it was only higher than 8.0%, respectively, after domestication. The percentage increase in the activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GSH-PX), and catalase (CAT) were higher than 25.2%, 23.7%, 14.9%, 21.5%, and 16.3%, respectively, in watercress leaves under salt stress, while they were only higher than 42.5%, 42.5%, and 16.3%, respectively, in watercress leaves under salt stress, and only higher than 8.0% after domestication. In terms of cation distribution, the percentages of decrease in K+/Na+ ratio in leaves and roots were higher than 89.4% and 84.1%, respectively, due to salt stress, but only higher than 64.8% and 60.6%, respectively, after domestication.In conclusion, low salt stress negatively affects watercress growth and its physiological and biochemical responses, but short-term domestication ameliorates the effects of salt stress.