Abstract:
Objective Changes on the key microbial communities in the continuously cropped rhizosphere soil (CCRS) of Achyranthes bidentata Blume were studied to analyze the allelopathic effect for operational improvement on cultivation of the medicinal plants.
Method The community structures of Bacillus spp. and Fusarium spp. in the rhizosphere soil of A. bidentata under 1, 10, and 15 years of consecutive monoculture were determined using denaturing gradient gel electrophoresis (DGGE). Soil sample from a virgin land was used as control (CK).
Result Abundant Bacillus spp. dominated by B. stubtilis and B. cereus were isolated from the CCRS specimens. The CCRS under 10-year (10Y) and 15-year (15Y) of continuous cropping had a greater relative content of B. subtilis and B. halodurans than their 1-year (1Y) counterpart. With respect to Fusarium spp., the number of bands and species were relatively few, the community structure tended to be similar between CK and 15Y as well as between 1Y and 10Y, and F. solani and F. oxysporum being the dominant species. The qPCR results also indicated that continuous monoculture of A. bidentata increased the abundance of the beneficial bacteria but kept that of the harmful Fusarium spp. largely unchanged.
Conclusion Continuous cropping A. bidentata enhanced the diversity and abundance of the beneficial Bacillus spp. without encouraging the expansion of the pathogenic Fusarium community in the rhizosphere. It appeared that the rhizosphere allelopathy under the cultivation practice had created a healthy ecosystem that promoted the growth of A. bidentata.
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