Effects Of Potassium Fertilizer Application On Yield And Quality In Vegetable Soybean

Yield and quality are factors determining food and economic values of vegetable soybean. Thus, increasing the yield while improving the quality simultaneously has been the main concern for production and research in vegetable soybean [Glycine max (L.) Merrill]. Two vegetable soybean genotypes, cultivar No.l Edamame, CAS and Line-121from four application rates of K fertilizer at seeding along with normal N and P fertilizer application, and two foliar application at flowering stage and pod-setting stage were grown and implemented in a pot experiment. The purposes of this research were to examine the influence of K fertilizer application practices on yield and quality of vegetable soybean and to provide suitable cultivation approaches for the production of vegetable soybean in Heilongjiang province. The results are as follows:1. The application of potassium (K) fertilizer increased the fresh pod yield at marketable stage and the seed number at physiological maturity stage. The fresh pod yield and seed number increased with the increase in the rate of K fertilizer application, while standard pod number per plant was not affected by K application. The highest fresh pod yield was ontained at the K rate of120kg·hm-2. Additional foliar application of K fertilizer could further increase the fresh pod yield of vegetable soybean. The maximum fresh pod yield was achieved with foliar application with K rate of120kg·hm-2.2. The K fertilizer improved the appearance quality, food quality and nutrition quality of vegetable soybean. The best quality was also obtained at the K rate of120kg·hm-2. K fertilizer application at seeding plus the foliar application increased pod length and width, but had no influence on pod thickness. The sucrose content and fructose content increased with the rate increase of K fertilizer application, while the total soluble sugar also increased. Additional foliar application of K fertilizer further increased the sugar content in vegetable soybean seed. Protein content was decreased while oil content was increased by K application. This trend was more obvious at higher K fertilizer rate. Foliar application had no influence on protein content, but had significant influence on oil content in Line121.3. The K fertilizer application increased above-ground potassium accumulation and leaf chlorophyll content. The maximal potassium accumulation was achieved at K rate of180kg·hm-2and highest leaf chlorophyll contenat was at rate of120kg·hm-2. Foliar K application had no effect on potassium accumulation in cultivar No.1Edamame, CAS, but significantly increased potassium accumulation in Line121at flowering and pod-setting stage. Leaf chlorophyll a was quite responsive to K application. Foliar application increased leaf chlorophyll content at flowering and pod-setting stage. Cultivar No.1Edamame, CAS was relatively sensitive to foliar K application.