Effects of Potato Onion Companion on Tomato Root Morphology and Rhizospheric Soil Environment

The companion planting of tomatoes and potato onions was used as materials with adoption of pot planting, two planting modes were set, monoculture of tomatoes and companion planting of tomatoes and potato onions.The effects of intercropping potato onions on tomato root morphology and rhizospheric soil environment were studied after 30 days of association, in order to provide reference for the promotion of intercropping potato onions and tomato association cultivation.The results showed that plant dry weight, the shoot dry weight and root dry weight of potato onions accompanying tomato increased significantly, associated cultivation significantly improved the tomato root-shoot ratio and root activity, root length, root surface area, root volume and average root diameter of potato onions accompanying tomato were significantly higher than monoculture.Compared to monoculture, the specific root length of tomato roots with a diameter between 0-0.50 mm in companion planting was significantly smaller（P＜0.05）,while specific root length of tomato roots with a diameter between or at 0.51-1.00 mm, 1.01-1.50 mm, 1.51-2.00 mm and ＞4.50 mm was significantly greater（P＜0.05）.In companion planting, the contents of microbial biomass carbon, nitrogen and phosphorus in the rhizospheric soil of tomatoes were significantly increased, and the associated tomato rhizosphere soil microbial biomass C/N,C/P and N/P ratio was significantly lower than monoculture tomatoes.The activity of dehydrogenase and urease and alkaline phosphatase in tomato rhizosphere soil and electrical conductivity（EC） of rhizospheric soil of tomatoes were improved, while the pH and the accumulated reducing substance of soil were significantly lowered.In summary, the companion of potato onions changes the tomato root morphology, whereby the growth of tomatoes was promoted due to improved availability and absorption of soil nutrients in rhizospheric soil.