| Watermelon wilt disease is one soil born disease which lead by Fusarium oxysporum f.sp .niveum. This disease causes great economical loss on watermelon from seedlings to grown plant. To decrease damage on watermelon, a lot of controlling methods had been developed. However the control methods operated over this disease have different weakness and disadvantages. Like the fungicide, this induces great health concerns to people and environment for its high toxin contents and residues. Furthermore, it is difficult to operate the traditional way of different management techniques in practice. In China, there is little information on wilt disease resistant watermelon in breeding. Therefore, to explore one biocontrol technique without contamination to the environment and threat to people is urgent to solve the problem and protect watermelon from wilt disease.In this research, antagonistic endophytic bacteria isolated from root of wilt disease resistant melon(MR-1) and tillered-onion extractions were employed to assess the biocontrol effecy on watermelon.The control effecy of antagonistic endophytic bacteria on watermelon wilt disease. 17 strains of antagonistic endophytic bacteria were isolated from the root of wilt disease resistant melon(MR-1). 4 strains of antagonistic endophytic bacteria (Mg2,Mg9,Mg15,Mg16) were obtained with antagonistic effect through confront culture method. According to the growth rate assessment of wilt disease hyphae treated by the fermentation liquid of antagonistic endophytic bacteria, the Mg 15 had the highest antagonistic effect with 77.09% of hyphae was inhibited and even deformed. The original fermentation liquid showed the highest inhibitation effect as only 7.86% of spores germinated and without harm to watermelon seeds. Given the field experiment, the disease index of wilt disease resistant watermelon was 14.67% compared with the control group and 72.83% of watermelon seedlings were not infected after treated by the Mg15 fermentation liquid while the wilt disease susceptible watermelon was 12.67% and 69.34% of watermelon seedlings were not infected.Control effecy of tillered-onion extractions on watermelon wilt disease. According to the result in the laboratory, the inhibition to Fusarium oxysporum spore germination increased with the increasing of tillered-onion extraction concentration. 4.66%, 25.71%, 39.53%, 68.58%, and 73.93% Fusarium oxysporum spore germinated after treated by the tillered-onion extraction with concentration of 1000 mg/mL, 500 mg/mL, 250 mg/mL, 125 mg/mL, 62.5 mg/mL, respectively. The results in field experiment demonstrated that the concentration of 500 mg/mL, 250 mg/mL, and 125 mg/mL had control effect on watermelon wilt disease. When employing 250 mg/mL of tillered-onion extraction, the control effect reached highest place on both wilt disease resistant watermelon seedlings and wilt disease susceptible ones. The disease index on resistant watermelon seedlings was 18% whereas 21.33% on susceptible watermelon. |
