Journal of Society & Technology 5:48-55 (2015) The Use of Desalinated Seawater from a Solar Still Favors the Growth and Yield of Lactuca sativa L. in a Hydroponics System Vivencio A. Pelesco 1 * and Feliciano B. Alagao 2 1 Naval State University – Biliran, Biliran, Philippines 2 Mindanao State University – Iligan Institute of Technology, Iligan City, Philippines Abstract The study explored the potential of utilizing the desalinated seawater produced by a solar still as irrigation water to a hydroponic vegetable production system. A field experiment was laid out in Randomized Complete Block Design to compare the growth and yield of Lactuca sativa L. using the desalinated seawater from a solar still and a tap water. The growth and yield of L. sativa are significantly higher using the desalinated seawater because of the latter’s quality that is more suitable to plants’ requirement in hydroponics. The desalinated seawater does not contain a significant amount of minerals that would react with the hydroponic fertilizer and would eventually reduce the availability of nutrient elements for plant growth and nutrition. Higher yield of the plant in hydroponics can, therefore, be achieved using desalinated seawater from a solar still. Keywords: irrigation water, renewable energy, hydroponics system, island villages and coastal lands Introduction The effect of climate change had caused a gradual reduction of arable land and fresh water due to salt water intrusion. In areas such as island villages and coastal lands where arable soil and fresh water is very limited or not available at all, the use of desalinated seawater for irrigation in a soilless crop production system is a promising alternative. With the rising cost of conventional energy, tapping of renewable energy technologies such as the solar thermal energy technology for desalination comes as a very attractive option. Solar still is basically a simple solar thermal energy technology to desalinate seawater through the evaporation-condensation processes utilizing the renewable and free solar energy. Several solar desalination system concepts have been developed for irrigation in arid areas conditions and were described in Chaibi & Bourouni (2007) and Chaibi & El-Nashar (2009) such as: a) the integrated greenhouse solar still, b) a closed greenhouse at the University of Hanover in Germany from 1979 to 1984 with integrated solar water desalination called ITG-system, c) a greenhouse with solar distillation using the Bettaque concept, d) naturally ventilated greenhouses solar still, e) a multi-stage roof integrated solar still, and f) integrated solar system greenhouse based on the Bettaque system. Chaibi and Bourouni (2007) revealed that water production from a solar still is less than the water requirement for a crop grown in an open irrigated field, but may be suitable to supply fresh water to protected cultivation. In an irrigated field, aside from evapotranspiration, water can be lost through deep percolation and seepage whereas, in hydroponics, irrigation water is lost only through evapotranspiration. According to Abd-Elmoniem et al. (2006), hydroponics needs only about 1/25 water as in conventional farming. Despite the numerous studies on the application of desalinated water for irrigation, the growth and yield of plants under this method as compared to the conventional *Correspondence: vapelesco@nsu.edu.ph