Effects Of Root Exudates On The Pathogen Of Cotton Verticillium Dahliae

Verticillium wilt caused by Verticillium dahliae is an important soil borne vascularbundle system diseases. At present, the disease has caused huge economic losses of cottonproduction in China, and has become the main obstacle to cotton yield. But as a long survivaltime of initial inoculum source, pathogen pathogenicity and poor cotton varieties resistance,prevention and control of cotton Verticillium wilt is extremely difficult. Crop intercropping orrotation which using the inhibition activity of plant root exudates, is based on plant sourceinstead of chemical fungicide. Because of the advantage, simple, efficient and cheap, it hasbecome an effective means of prevention and treatment of diseases. Therefore, we carried outthe research on the effect on root exudates of five kinds of the non-host plants (Chinese chives,welsh onion, mint, ageratum and lavender) to inhibition on mycelium, conidium andmicrosclerotium. In order to screen suitable intercropping or rotation crops to cotton, and toprovide theoretical basis for prevention and control of cotton Verticillium wilt. The mainresults were shown as below:1. Determine the root exudates’ effect on mycelium growth of V. dahliae.Growth rate method was chosed to compare the different root exudates’ inhibition on themycelium growth of V. dahliae by various concentrations, and calculated the rate of inhibition.The results indicated that the5kinds of root exudates all showed inhibition effects on V.dahliae, but the effects were different: Chinese chives had the strongest inhibition effectamong the5kinds of plant, the rate is22.74%to87.92%; mint took the second place, the rateis24.49%to85.30%; ageratum’s inhibition effect was the weakest, the rate was17.86%to70.02%. With the increasing of the concentration, the effects increased, but the dividesbetween the different treatments became narrow. Among them, the inhibition rate of Chinesechives increased rapidly, and the other four’s increases were slow.2. Measure the root exudates’ effect on spore germination of V. dahliae.After observing various root exudates’ effect on V. dahliae by different treatment time,calculating the inhibition rate of spore germination. The results showed that the root exudatesof the5plants all inhibited the spore germination of V. dahliae. With the increasing of theconcentration, the effects increased, but the increase amplitudes were different. Under the same concentration, inhibition has declined along with the time. V. dahliae was most sensitiveto the root exudates of Chinese chives. The inhibition effect of Chinese chives was thestrongest. Overall, Chinese chives had the strongest inhibitory effect, mint took the secondplace and lavender was the weakest.3. Determine the effects of root exudates on microsclerotium germination of V. dahliae.Microsclerotium were planted into the root of pot plant, and we calculated thegermination rate of microsclerotium over certain processing time. The results showed that theroot exudates of the5plants all inhibited the microsclerotium germination of V. dahliae.During the treatment time, the inhibition effect increased. It increased fast, and then turned toslow. Chinese chives showed the strongest inhibition on the microsclerotium, performedsignificantly above other4plants. The microsclerotium was most sensitive to the rootexudates of Chinese chives, welsh onion was at the lower degree, ageratum and lavender hadthe same weakest effect.