Response of eggplants grown in recirculating nutrient solution to salinityimposed prior to the start of harvesting

The effects of exposing eggplants grown in recirculating nutrient solution to salt stress (6.1 dS m(-1)) from planting until the beginning of harvesti ng, on plant growth, yield and macronutrient status was investigated. The s alinity was imposed by adding to a basic nutrient solution either additiona l nutrients at two cation ratios or NaCl. The results showed that the expos ure of plants to salinity prior to the beginning of harvesting reduced both vegetative growth during that time and early fruit yield, but the depressi on of the latter was more severe. The restriction of the early yield was a result of a reduced mean fruit weight due to a lower fruit water content. T he detrimental effects of salinity on the mean fruit weight disappeared 25 d after discontinuing the salinity treatments. As a result, the total yield obtained after five months of harvesting was not influenced by exposing th e plants to salinity prior to the beginning of harvesting. The salinity sou rce had no specific effect on plant growth. Moreover, the increase of salin ity up to 6.1 dS m(-1) did not cause any specific nutritional imbalance or toxicity to the plants, irrespective of the salts used to achieve it. It is suggested that the electrical conductivity of the nutrient solution may be raised to 6.1 dS m(-1) to control excessive vegetative growth in eggplants grown hydroponically. However, salt treatment should be terminated either at the first harvest, if the total yield is more important than the early y ield, or three weeks earlier, if the opposite is true.