Mechanism Research On Sparingly Soluble Phosphorus By Different Chinese Milk Vetch Genotypes

Screening and breeding P efficient genotypes for Chinese Milk Vetch, which could take full advantage of potential soil phosphorus, solve the problem of low soil P availability, save resources, prevent pollution, improve soil quality and keep sustainable development of agriculture, was greatly important and efficient. In this study, five different genotypes of Chinese Milk Vetch on the sparingly soluble phosphate (Al-P and Fe-P) activation, uptake and utilization were studied through solution culture and sand culture experiment, which had a preliminary dicussion on the activation of insoluble phosphate uptake mechanism by Chinese milk vetch genotypes. The main results were as follows:1 Activation mechanism on sparingly soluble phosphate by root exudates of different genotypes1.1 Chinese Milk Vetch genotypes in plant height, stem diameter, branch number and other agronomic traits had significant difference under P-deficiency and normal P supply, which was likely to be lack of P stress on crops to adapt to adversity. Under phosphorus deficiency conditions, root radius for different genotypes was reduced, however, the root shoot ratio and specific surface area increased significantly higher than normal P supply.1.2 Root exudates on insoluble Al-P and Fe-P had certain activation capacity under P-deficiency and normal P supply. The activation values for Al-P and Fe-P were 36.40^-157.39 ug g^-1,32.20^-139.42ug g^-1. For CK, the activation amount of root exudates on insoluble phosphate was higher than normal P supply. Chinese Milk Vetch root exudates on the activation capacity in Al-P was higher than in Fe-P.1.3 Root secretion of organic acids were oxalic acid, tartaric acid, citric acid, malic acid, maleic acid, succinic acid and so on. Under P deficiency, the organic acid secretion was significantly higher than normal P supply for most genotypes. P efficient varieties of No.1 Min Zi, No.5 Zhe Zi and No.6 Min Zi of organic acid secretion were significantly higher than Yi Jiang Zi, Yu Jiang Da Ye, and the ability of the organic acid activation had significant differences.2 Impact on uptake and utilization of sparingly soluble phosphate by different genotypes 2.1 Chinese Milk Vetch genotypes grown in the insoluble phosphate was significantly different. For plant height, stem diameter and branch number, it basically showed K-P> Al-P> Fe-P> CK, and it was significant difference between two kinds of insoluble phosphate. For most Chinese Milk Vetch genotypes for Al-P in the shoot, root and total fresh and dry weight were significantly larger than Fe-P, which showed that Al-P was more easily absorbed by Chinese Milk Vetch. Biomass for No.6 Min Zi and No. 1 Min Zi in the uptake of insoluble phosphate were significantly higher than Yi Jiang Zi, Yu Jiang Da Ye.2.2 Chinese milk vetch genotypes among upground, underground and total P uptake were different, which expressed as K-P>Al-P>Fe-P>CK, namely, K-P was biggest, and CK was lowest in the uptake capacity of different phosphorus sources. No.6 Min Zi and No. 1 Min Zi on the insoluble phosphate of P uptake were higher than the other three species, indicating that No.6 Min Zi and No. 1 Min Zi on the insoluble phosphate solution had strong uptake capabilities. According to the relation between plant P uptake and biomass.Uptake of the nutrient content increased with the biomass of Chinese Milk Vetch, which was a significant positive correlation, especially for insoluble Al-P and Fe-P uptake and utilization.