Dynamic Changes Of Peach Root Residues And Rhizosphere Soil Allelopathy

In recent years, the peach cultivated areas in our country are under steady development, but the arable land resources are limited. To investigate the causes and mechanism of peach replanted problem, our research analyzed the phenolic acid derivates in the extracts of peach root residues and rhizosphere soil, and lettuce seeds were used for bioassay. At the same time the dynamic changes of soil enzyme and soil physic-chemical parameters were also analyzed in this research. The major results are as follows:1. The study on nutrient of dead and living peach trees rhizorsphere soil. In five months all over the year, the content of alkali-hydrolyzable N, available P, available K and organic matter in rhizosphere soil of dead peach trees were generally higher than that in living peach trees. Besides, the pH of rhizosphere soil of living trees were higher than that of dead trees through the year except for July.2. The study on the relationship among the activity of some soil enzymes, soil nutrient and soil pH value in dead and living peach trees rhizorsphere soil. A significant positive correlation (0.9525*) was found between the urease activity and pH. And there was a significant positive correlation (0.9478*) between the acid phosphatase activity in rhizosphere soil of living trees and available P.3. HPLC was used for qualitative and quantitative analysis of phenolic acid derivates in the root residues and the rhizosphere soil of both dead peach trees and living peach trees, only benzoic acid were found, and the content of benzoic acid in the soil and root residues were:root residues> rhizosphere soil of dead trees> rhizosphere soil of living trees.4. Lettuce seeds were used as allelochemicals receptor for biossay of root residues and soil extracts. The biossay of root residues and soil extracts showed a significant concentration effect which meant higher concentration of the extracts of allelopathic effect is stronger concentration gradients of extracts of both dead and living peach trees root rhizorsphere soil and root residues led to stronger allelopathic effect and higher RI value.