连作西洋参根际真菌群落差异及其在土壤药剂处理后的初步分析

Effect of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium

目的:分析连作西洋参根际真菌群落的特点及土壤药剂处理对其的影响,探讨西洋参生长与根际真菌区系的相关性以及西洋参连作障碍的土壤生态机制。方法:采用田间随机区组实验,选择种植过4年以及连续育苗2次每次2年的老参地土壤连作西洋参,另设碳素肥加低毒化学农药及植物源农药对老参地土壤进行消毒处理,调查各处理组西洋参的生长及病害发生情况,同时采用稀释平板法分离根际真菌,以Shannon-Wiener指数(H'),Margalef丰富度指数(Ma)和Pielou均匀度指数(J)作为真菌群落多样性的测度。结果:与未种过参的新地相比,重茬种植的西洋参秋季存苗数、根重均明显降低,根病指数显著升高(P<0.05),根际真菌数量降低50%～63%,多样性指数(H')降低39%～43%,群落构成的变化主要表现为青霉属及曲霉属真菌的比例增大。根际土壤真菌的多样性指数与西洋参根病指数呈显著负相关(r=-0.970,P=0.006)。碳素肥加低毒化学农药菌线威处理老参地土壤,对提高重茬西洋参的存苗数及根重有较好的效果,一定程度提高根际真菌多样性。结论:重茬西洋参根际真菌数量和多样性降低,群落构成发生变化。碳素肥加菌线威处理对连作西洋参生长具有较好的改善作用。

Objective： To analyze the effects of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium, and the correlation between rhizosphere fungal community and growth of P. quinquefolium. Method： Field plot trail of continuous cultivated P. quinquefolium was conducted, meanwhile continuous cropping soil was treated by organic carbon fertilizer plus methylene dithiocyanate and Kingbo respectively. The rate of seedling survival, root disease index and root weight were investigated. Dilution plating was used to analyze the rhizosphere fungal community, multiple comparisons including H, Ma and J were performed between rhizosphere fungal community and growth of P. quinquefolium. Result： As to P. quinquefolium planted in continuous soil, the rate of seedling survival, root weight decreased, root disease index increased remarkably （P 〈 0.05）. Meanwhile the fungal counts decreased 50%-63% , the diversity index （H＇） decreased 39%-43% , while the ratio of Penicillium and Aspergillus increased. There was a significant negative correlation between rhizosphere fungal diversity and P. quinquefolium root disease index （ r = - 0. 970, P = 0. 006）. Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the rate of seedling survival and root weight, and could partly increase the rhizosphere fungal diversity. Conclusion： In continuous cropping soil of P. quinquefolium, the rhizosphere fungal counts and diversity index decreased, meanwhile the fungal community composition changed. Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the growth of continuous cultivated P. quinquefolium.