Effect of Tillered-Onion (A.cepa var.agrogatum Don.) Bulb Extraction On Watermelon Fusarium Oxysporum and the Control Efficacy in Greenhouse

Fusarium oxysporum is a vascular disease of watermelon and leads to serious economic loss on watermelon production worldwide. A lot of chemical methods have been used to control this disease, but the secondary pollution to environment and effect on health are considered by the public gradually. Thus, in this research, a biocontrol method using different concentration of tillered-onion (A.cepa var.agrogatum Don.) bulb extraction was studied to estimate the control efficacy on Fusarium oxysporum. According to the experiment results, when treated by the tillered-onion extraction with concentration of 1000 mg/ml, 500 mg/ml, 250 mg/ml, 125 mg/ml and 62.5 mg/ml, the rates of Fusarium oxysporum spore germination were 4.66%, 25.71%, 39.53%, 68.58% and 73.93%, respectively. So the inhibition to Fusarium oxysporum spore germination enhanced with the increasing of tillered-onion extraction. Besides, different concentration of tillered-onion extraction also inhibited Fusarium oxysporum hyphae growth. The rates of hyphae inhabitation were 32.37%, 38.68%, 45.53%, 53.42% and 69.21% treated by 62.5 mg/ml, 125 mg/ml, 250 mg/ml, 500 mg/ml and 1000 mg/ml of tillered-onion extraction. The Analysis of Variance showed that the least of hyphae dry weight (27.1 mg) was obtained treated by 1000 mg/ml of tillered-onion extraction. 250 mg/ml of tillered- onion extraction was the best to control Fusarium oxysporum in greenhouse. When treated by this, the control efficacy reached 63.5% on resistant watermelon variety and 65.96% on susceptible watermelon variety. Therefore, the tillered-onion could be used as one favorable biocontrol candidate to Fusarium oxysporum.

 
Key words: Fusarium oxysporum; Tillered-onion (A.cepa var.agrogatum Don.); Biocontrol