Water Use and Yield Responses of Chile Pepper Cultivars Irrigated with Brackish Water and RO Concentrate.

Fresh water availability is declining in most of the semi-arid and arid regions across the world including southwestern United States due to low rainfall and high evapotranspiration. Use of marginal quality of water has been examined for agricultural use in order to conserve potable fresh water. Along with saline water available from natural saline aquifers, concentrate produced from RO (reverse osmosis) desalination process can also be a potential source of irrigation. Chile pepper (Capsicum annuum) is an important cash crop of southwestern United States. This greenhouse study evaluates the yield and water use of five selected chile pepper cultivars which were irrigated with natural saline well waters and concentrate coming out of the RO system. The four saline water treatments used for irrigation were tap water of EC 0.6 (control), well waters of EC 3 and 5 dS/m and RO concentrate of EC 8 dS/m. The yield of chile peppers stayed constant upto a soil EC of about 2 dS/m and then declined exponentially with increase in soil salinity.  The cumulative evapotranspiration of chile peppers was found to be decreased as a function of irrigation water salinity with time. The amount of total deep percolation increased significantly with the increase in salinity of water. Based on the water use efficiency (WUE_Y) of selected chile pepper cultivars, a saline water of EC ≤ 3 dS/m can be used as irrigation. Environmentally sound reuse of RO concentrate will encourage implementation of desalination technique in fresh water scares areas and also increase the potential of greenhouse chile pepper cultivation.