Studies on Herbicidal Activity of Fermentation Products of Xi Nong No.24 Strain against Amaranthus retroflexus L.

The strain of Xi Nong No.24 was separated from the soil collected in Qinling,Shaanxi province. It was indentified to be streptomyces,taking as object,by means of micro-pannikin, herbicidal activity had been measured on Amaranthus retroflexus L. by fermentaing,eluting and Pre-HPLC.The results of biological test showed that the fermentation products of No.24 had an intensive herbicidal activity against Amaranthus retroflexus L., and had an inhibition of 80.6% to taproot, an inhibition of 66.5% to caulis and an inhibition of 26.7% to bourgeon. Exchange liquor had an inhibition of 93.1% to taproot, an inhibition of 86.2% to caulis and an inhibition of 42.9% to bourgeon.Eight fractions were isolated from the fermentation products of No.24 strain by Pre-HPLC. The fraction No.4 had the most intensive herbicidal activity. The inhibiting rate of No.4 was 95.8%, 93.76% and 86.36% against the taproot ,caulis and the bourgeon of Amaranthus retroflexus L.respectively.