Abstract:

To study the antibacterial activity of extracts of Brassica juncea, lay a foundation for the development of B. juncea as a fungicide for agricultural production, and provide a basis for the rational use of B. juncea resources, we tested the antibacterial activities of extracts of B. juncea against Fusarium oxysporum f. sp. niveum, Rhizoctonia solani, Botryosphaeria parv and Phytophthora parasitica var. nicotianae by means of mycelium growth rate method. The results showed that: different organic solvent extracts from B. juncea had certain inhibitory effect on watermelon fusarium wilt; the antibacterial effect of extracting with 95% ethanol was the best, and the antibacterial rate of the extract could reach more than 90%; its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MFC) were 0.5 g/mL and 1.0 g/mL, respectively; through the determination of virulence equation, its half bacteriostatic concentration was 0.2212 g/mL. The antibacterial activity of the other 10 plant phytopathogens showed that: the ethanol extracts of B. juncea had strong antibacterial activity against 4 phytopathogens, such as Rhizoctonia solani, Botryosphaeria parv, Phytophthora parasitica var. nicotianae, and Sclerotinia sclerotiorum with the EC₅₀ 0.0898 g/mL, 0.1265 g/mL, 0.1679 g/mL and 0.1685 g/mL, respectively, and the inhibition effect against the Colletorichum gloeosporioides was the weakest, and the EC₅₀ was 0.5833 g/mL. The extracts of B. juncea have strong antifungal activities with broad control spectrum, and it is worth further researching.

Key words: extracts from Brassica juncea, watermelon Fusarium wilt, phytopathogen, antibacterial activity