ABSTRACT
<p><b>OBJECTIVE</b>Through correlation and path analysis between total saponins content in rhizome/mycorrhizal infection rate in roots of Pairs polyphylla var. yunnanensis and soil factors, to make an inquiry into the role of soil factors in the quality formation of P. polyphylla var. yunnanensis.</p><p><b>METHOD</b>Tested total saponins in rhizome, mycorrhizal fungal infection rate in root and physical and chemical properties in rhizosphere soil in 25 different growth areas, and statistically analyzed the relationship between total saponins in rhizome/mycorrhizal infection rate in roots of P. polyphylla var. yunnanensis and soil factors by using correlation and path analysis.</p><p><b>RESULT</b>The symbiosis relationship between AM mycorrhizal and roots of P. polyphylla var. yunnanensis were better established under natural condition, of which the infection ratio between 36.41%, 83.37%. There were significantly positive correlation between total saponins content in rhizome and urease activity or alkaline phosphatase activities or organic matter in soil, but there was significantly negative correlation between total saponins content and bulk density. There was significantly positive correlation between AM infection ratio and alkaline nitrogen. Path analysis indicated that total saponins of rhizome mainly affected by alkaline nitrogen in soil rhizosphere, secondly by soil organic matter and soil urease activity. While the mycorrhizal fungal colonization ratio was mainly affected by soil pH, secondly by alkaline nitrogen, urease activity, and available phospherus in soil.</p><p><b>CONCLUSION</b>There is closed relationship between quality formation of P. polyphylla var. yunnanensis and soil factors. Path analysis is better for reflecting the contribution of soil factors to total saponins and mycorrhizal infection ratio.</p>