Growth Responses of Seashore Paspalum (Paspalum vagenitum Swartz) to Alternate Levels of Salinity Stress.

Growth responses of Seashore Paspalum (Paspalum vaginatum Swartz), cv. Sea Isle 2000 in terms of shoot and root lengths, fresh and dry weights, and the general quality of the grasses were studied hydroponically in a greenhouse under alternate levels of salinity stress. The experiment was arranged as a split plot based on randomized complete block design with four replications. Grasses were grown from the stolons. After 4 months of growth under normal condition and complete establishment, the salinity stress phase of the study started. The grasses of one plot were grown under control (no-salt) and constant salinity levels (EC 10, 20, and 30 dSm^-1) for 8 weeks. However, the grasses of the other plot were grown for a week in nutrient solutions with the above salinity levels, then, the nutrient solutions were changed to control (no-salt) and the grasses were allowed to grow under the control condition for a week. This alternate weekly growth of the grasses under control and salinity stress conditions were continued for 8 weeks too, the same period, as the constant salinity treatments plot. During this period, shoots and roots’ lengths and clippings fresh and DM weights of the grasses were measured weekly and the grasses’ general qualities were evaluated. At the termination of the experiment, roots were also harvested, fresh and DM weights were recorded. The results showed at each salinity level, all the growth parameters significantly increased in grasses grown under alternate salinity/control condition compared to their corresponding treatments under constant salinity stress condition. The acclimation of the plants to salinity stress and their recovery from the stress under the control (no-salt) condition may have been the main reason for the increased in their growth under alternate salinity stress compared to that under the constant salinity stress condition. Increase in the growth rates of the grasses under alternate salinity/control condition compared to their corresponding values under constant salinity stress levels was substantially higher at the lower levels of salinity (EC 10, and 20 dSm^-1). General quality of the grasses grown under alternate salinity stress condition also significantly improved compared to the ones grown under corresponding constant salinity stress levels. These promising results can be beneficial to the growers when there are various sources of saline waters available for irrigation. By alternate use of the waters with different salinity levels for irrigation, there may be some improvements in plant growth as well as reduced in adverse effects of salinity on plants.