Objective To compare anti-fungal effects of aqueous extracts of different plants on Fusarium oxysporum f. sp. cubense race4 (FOC4), the causal agent of banana wilt, and further clarify the releasing approaches of anti-fungal compounds from leek (Allium tuberosum Rottler) and Ageratum conyzoides L.
Method Mycelial growth rate method and spore germination method were used to examine the inhibitory effects of aqueous extracts from 12 plant species as well as volatiles from leek and A. conyzoides on mycial growth and spore germination of FOC4.
Result Aqueous extracts of leek and A. conyzoides showed strong inhibitory effects on FOC4 colony growth, the inhibition rates were 71% and 69% respectively. Dichloromethane extracts and residuals of aqueous extracts from leek leaves showed the inhibition rates of 18.7% and 13.0% respectively, and dichloromethane extraction and residuals of aqueous extracts from leek roots showed the inhibition rates of 39.8% and 22.1% respectively, which suggested that the main active ingredients were low water-soluble organic compounds. The antifungal effects of leaf volatiles showed stronger than those of root volatiles for leek. The volatiles from fresh leek leaves mashed in a sealed glass jar completely inhibited FOC4 colony growth at the concentration of 1.25 g/L, and FOC4 spore germination number was 35 per dish after treated with volatiles from leek roots at the same concentration. The inhibitory effects of aqueous extracts of A. conyzoides fresh leaves on FOC4 were obvious, and the inhibition rates were more than 50% at the concentration of 0.5 g/L. The inhibitory effects of A. conyzoides volatiles on FOC4 was not obvious suggesting that the main antifungal compounds of A. conyzoides were not volatiles.
Conclusion Aqueous extracts and volatiles from leek have strong inhibitory effects on FOC4, and leek volatiles show higher inhibitory effect. Aqueous extracts of A. conyzoides can inhibit FOC4 growth, but the inhibitory effects of its volatiles were not obvious.
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