EFFECT OF SALT STRESS IN LETTUCE CULTIVATION

     In many Mediterranean horticultural areas, the intensive use of water drawn from ground wells has caused seawater intrusion. As a consequence, water is getting more and more brackish. In some cases it can reach high levels of EC, that are not well tolerated by vegetables. Plants under salt stress condition may decrease the uptake of water and change the absorption ratio of nutrients. However, a high content of chlorides in water can reduce the absorption of nitrates and their accumulation in leaves. This work aimed to evaluate the effect of salt stress on quality and production of lettuce grown in soilless culture. A soilless cultivation was carried out under an unheated greenhouse in plastic containers filled with coconut coir dust. Lettuce plants of two cultivars were grown using a water supply containing four nutrient solutions with different electrical conductivity (1.6, 2.6, 3.6, 4.6 mS cm^-1). These variations were obtained by adding NaCl to the mother nutrient solution. An increase in salinity of the nutrient solution was associated with a reduction of marketable yield, average plant fresh weigth and leaf number per plant. Salinity influenced also the ratio and content of anions and cations in the plant.

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