Abstract:

In this study, the effect of phosphorus on the content of kernal isoflavone in different soybean varieties was analyzed. The best phosphorus levels of different genotype soybean varieties were explored, in order to increase the content of kernal isoflavone and improve their qualities. Three soybean varieties (‘Heinong-48’, high-protein cultivar; ‘Heinong-37’, middle cultivar; and ‘Heinong-44’, high-oil cultivar) were investigated. The soybean seeds were planted in pots and fertilized with 0.033 g of nitrogen (N) and potassium oxide (K2O) per kg soil. Four levels of phosphorus (P) treatment were designed, which were P1, P2, P3 and P4 (i.e., 0, 0.033, 0.067, and 0.100 g of phosphorus pentoxide (P2O5) per kilogram of soil). The content of total kernal isoflavone in different soybean varieties was determined by ultraviolet spectrophotometry. The results showed that the content of total isoflavone under the P2 treatment was significantly higher than that of P1, P3 and P4 treatment in the same variety of soybean. The content of total isoflavone under the P2 treatment in the three soybean varieties (‘Heinong-37’; ‘Heinong-44’; ‘Heinong-48’) compared to the control group was increased by 3.7%, 4.3%, 3.8%, respectively. It showed that the content of total isoflavone in ‘Heinong-44’ was the highest under the same treatment in different soybean varieties. In the 12 treatment combinations, the content of total isoflavone in ‘Heinong-44’ was the highest under the P2 treatment. Significant differences were observed in the content of isoflavone between the varieties and levels of P treatments. These findings suggest that phosphorus affects the total content of isoflavone in the three soybean varieties, and appropriate amounts of P fertilization might contribute to improving the content of kernal isoflavone.