干旱区生态环境知识资源中心

Our objective was to find an experimental and theoretical relationship between the electrical conductivity (EC) of nutrient solutions applied in open and closed systems for hydroponically-grown plants in the semi-arid regions of southern Spain. The experiments took place in a plastic greenhouse and were conducted from 1995 to 1998. In the first two years, beans and cherry tomatoes were grown in the autumn and spring, respectively, and in the last year, cucumber was grown in the autumn and spring. Crops were grown in soilless culture using perlite bags. The treatments were as follows: (i) no re-use of the drainage nutrient solution, i.e., an open system, and (ii) re-use of 100% of the drainage nutrient solutions, i.e., a closed system. In our region, irrigation water EC varies from 1.2 to 0.6. In the closed system, we noted an increase in the salinity of the nutrient solution and have suggested different methods to avoid salinity in the closed system.