Abstract:

In order to screen and obtain the biocontrol strains with high herbicidal efficiency, the strain DT-15 isolated from the Mentha haplocalyx Briq. disease sample in Datong County of Qinghai Province was used as the research object, the pathogenicity test in vitro, herbicidal effect evaluation in vivo, safety evaluation, strain classification and identification, and the optimal carbon and nitrogen source screening were carried out in this research. The results showed that the pathogenicity of strain DT-15 to 3 weeds in vitro was Elsholtzia densa Benth> Semen abutili> Chenopodium album. In pot experiment, the incidence rate of C. album and S. abutili were more than 91%, the control effect of fresh weight were more than 94%, and it was relatively safe to the main crops of Triticum aestivum L., Pisum sativum L., Vicia faba L. and Brassica napus L.. The strain DT-15 was identified as Alternaria solani. By comparing the colony diameter and the OD value of spore suspension, wheat bran was selected as the optimal carbon source for mycelium growth, and NaNO₃ was selected as the optimal nitrogen source. Therefore, strain DT-15 has the potential to develop microbial herbicide for controlling some broad-leaved weeds in the fields of T. aestivum, P. sativum, V. faba and B. napus.

Key words: Alternaria solani DT-15, herbicidal activity, crop safety, optimum carbon and nitrogen sources