栽培年限对人参根际土壤微生物活性及微生物量的影响

Effects of growing time on Panax ginseng rhizosphere soil microbial activity and biomass

采用野外采样与室内土壤培养法,对3个栽培年限人参根际土壤微生物活性及微生物量变化进行研究,为阐明人参连作障碍机制提供理论依据。结果表明,人参栽培年限增加对人参根际土壤微生物活性及微生物量的积累均有显著抑制作用。与新林地土壤(R0)相比,人参根际土壤微生物的呼吸作用,纤维素分解作用和硝化作用均被显著抑制(P<0.05),且随人参栽培年限增加抑制作用逐渐增强。三年生人参根际土壤(R3)微生物的活性最低,R3微生物的呼吸作用比R0显著降低56.31%,纤维素分解作用比R0显著降低86.71%,硝化作用比R0显著降低90.53%。与R0相比,土壤微生物氨化作用被显著促进,且随栽培年限增加有先增强后减弱的趋势,R1,R2,R3的氨化作用强度分别比R0显著增加32.43%,80.54%,66.64%。人参根际土壤微生物量碳(SMB-C)和微生物量氮(SMB-N)含量与R0相比均呈显著减少趋势,且随人参栽培年限增加,各栽培年限土壤的SMB-C差异显著,但SMB-N的变化不明显。R3的微生物量最低,其SMB-C比R0显著降低77.30%,SMB-N比R0显著降低69.36%。人参根系分泌物积累所导致的根际微生物种类、数量与活性变化及根际土壤微生态失衡是人参连作障碍的主导因素。

Using the field sampling and indoor soil cultivation methods, the dynamic of ginseng rhizosphere soil microbial activity and biomass with three cultivated ages was studied to provide a theory basis for illustrating mechanism of continuous cropping obstacles of ginseng. The results showed that ginseng rhizosphere soil microbial activity and biomass accumulation were inhibited observably by growing time. The soil respiration, soil cellulose decomposition and soil nitrification of ginseng rhizosphere soil microorganism were inhibited significantly （ P 〈 0.05 ）, in contrast to the control soil uncultivated ginseng （R0）. And the inhibition was gradual aug- mentation with the number of growing years. The soil microbial activity of 3a ginseng soil （R3） was the lowest, and its activity of soil respiration, soil cellulose decomposition, soil ammonification and soil nitrification was lower than that in R0 with 56.31%, 86.71% and 90.53%, respectively. The soil ammonification of ginseng rhizosphere soil microbial was significantly promoted compared with RO. The promotion was improved during the early growing time, while the promotion was decreased with the number of growing years. The soil ammonification of R1, R2 and R3 were lower than that in R0 with 32.43%, 80.54% and 66.64% separately. The SMB-C and SMB-N in ginseng rhizosphere soil had a decreased tendency with the number of growing years. The SMB-C difference among 3 cultivated ages was significant, while the SMB-N was not. The SMB of R3 was the lowest. Compared with R0, the SMB-C and the SMB-N were significantly reduced 77.30% and 69.36%. It was considered by integrated analysis that the leading factor of continuous cropping obstacle in ginseng was the changes of the rhizosphere soil microbial species, number and activity as well as the micro-ecological imbalance of rhizosphere soil caused by the accumulation of ginseng rhizosphere secretions.