Augmentation of antioxidant constituents by drought stress to roots in leafy vegetables.

摘要

Plants can synthesize some antioxidants, including L-ascorbic acid (AsA) and polyphenols, in response to environmental stresses. Antioxidants detoxify reactive oxygen species in plants and also aid in human health. In this study, it was demonstrated that a novel hydroponic treatment can increase leafy vegetable nutritional quality without retarding growth. Leaf lettuce was grown hydroponically and subjected to rhizosphere drought stress by lowering the water level in the solution tub before harvesting. Appropriate drought stress using this method could increase AsA, polyphenols and sugar content by 24, 50 and 17%, respectively, and decrease nitrate nitrogen content by 18% without reducing yield. Similar effects of drought stress on AsA content were observed in 4 other plant species. It is concluded that this hydroponic method has a universal potential to increase leafy vegetable quality without reducing yield in controlled environments such as plant factories.