Effects of Plant Physiological Regulators on Nitrate Accumulation and Yield in Four Vegetable Crops

In order to investigate the effect of plant physiological regulators and fertilization on nitrate accumulation and yield in leafy vegetables with different fertility,four vegetables were treated with auxin,gibberellins and microelement amino acid chelate in combination with kinds of conventional fertilization methods.The results indicated that the yield of pakchoi in two soils slightly decreased,but nitrate content significantly reduced by spraying three plant physiological regulators with 30% or 50% of conventional fertilization;while the yield of lettuces was roughly the same and nitrate content slightly decreased with the same treatments.Radish sprouts and water spinach grown on basis of the first fertilization soil were only treated by spraying plant physiological regulators.The nitrate content and yield of radish sprouts was roughly the same;while the nitrate content and yield of water spinach was not significantly different between treatments,except the nitrate content with NPK treatment in Ningxiang soil was significantly higher than the other treatments.The soil nitrate content after four leafy vegetables harvested had a very small influence,except that was significantly decreased in Ningxiang soil with different treatments compared to NPK treatment after water spinach harvested.It suggested that spraying plant physiological regulators could reduce the fertilization usage and nitrate accumulation in vegetable,but maintain the vegetable yields.However,the nitrate content in vegetable was related to the types of vegetable and soil.