Nutritional quality of hydroponically grown basil in response to salinity and growing season

Basil (Ocimum basilicum L.) is one of the most common aromatic herbs cultivated all over the world. It is widely used for aromatic and culinary purposes. Two greenhouse experiments were carried out to determine the effects of increasing the level of salinity in the nutrient solution (1 or 40 mM NaCl) during two consecutive growing seasons (summer and autumn) on growth, yield and leaf-quality traits of green sweet basil 'Mammolo' grown in an open-loop system. Increased salinity in the nutrient solution from 1 to 40 mM decreased fresh yield and final leaf area, with a more detrimental effect during the warm season. The percentage reductions in yield and leaf area in comparison with the non-saline control were respectively 30 and 42% in the summer cropping season and 20 and 16% in the autumn season. Increasing the NaCl concentration in the nutrient solution from 1 to 40 mM increased the hydrophilic antioxidant activity (HAA) and total phenolics (TP) by 87 and 17%, respectively, and reduced the nitrate content by 84%. When averaged over salinity level, TP increased and the nitrate content decreased in plants grown in summer compared with the autumn growing season.