Effects Of Combined Application Of Plant Growth Regulator DA-6 And Controlled Release Nitrogen Fertilizer On The Growth Of Spinach And Soil Fertility

Aminoethyl ester(DA-6) as a plant growth regulator, expands the plant leaf area, increases the content of chlorophyll and photosynthetic rate, prolongs the function period of leaves, promotes the synthesis and accumulation of plant carbohydrates, and consequently to improve the yield and quality of crops. The common applied approaches of DA-6 to crops were seed soaking, root irrigation, and leaf spraying. If the combination of DA-6 and nitrogen fertilizer was performed, less applied process and economic input was decreased. The seedling experiment and pot experiment were adopted to investigate the effects of DA-6 combined with controlled release nitrogen fertilizer on spinach growth and soil chemical properties. The finding from this study will provide the fundamental evidence to maintain high production and quality of spinach. The main results are as follows:1. The seed soaking of DA-6 pretreatment significantly promoted spinach seed germination. Physiological index of spinach plants were significantly improved. Compared to water soaking treatment, seed germination rate of DA-6 soaking was increased by 68%-102.86%. The content of chlorophyll a and chlorophyll b were increased by 13.45%-50.99% and 10.18%-75.55%, respectively, and the carotenoid content was increased by 9.82%-48.89%. Concerning the promotion to spinach germination and physiological index, the soaking concentration of 5 mg/L DA-6 treatment was the best one among all treatments. The root physical indexes of 20 mg/L DA-6 treatment roots were better than that of other treatments.2. The combined application of DA-6 and controlled-release fertilizer with base fertilizer treatment significantly increased the yield of spinach. In comparison with controlled release fertilizer(CK1), the combined application of DA-6 and controlled-release fertilizer markedly increased spinach yield by 53.05%-61.64%. The spraying DA-6 treatments did not pronouncedly improve the yield of spinach.3. Compared to controlled release fertilizer(CK1), the combined application of DA-6 and controlled-release fertilizer significantly elevated the vitamin C content and decreased the nitrate content in leaves, consequently improved the nutritional quality of spinach. The spraying treatments of DA-6 only increased the content of nitrate in spinach, but did not affect the quality of spinach.4. Controlled release nitrogen fertilizer significantly increased the demand for nitrogen fertilizer in the late growth stage, which provided sufficient nitrogen nutrition for the growth and development of spinach. The application of DA-6 had no significant effect on the chemical properties of the soil. DA-6 soaking treatments significantly promoted seed germination and improved the physiological condition of spinach. At the same time, with the bottom application of DA-6 and controlled release fertilizer increased the yield of spinach and improved the nutritional quality. Hence the combined application of DA-6 and controlled-release fertilizer was recommended to be widely used in the production of spinach.