不同土壤改良剂处理对连作西洋参根际微生物数量、土壤酶活性及产量的影响

以北京地区连作西洋参为研究对象, 通过3种土壤改良剂(熟石灰、EM菌剂、沼液)随机区组试验对其土壤理化性状、酶活性、根际微生物区系及产量进行了系统研究。结果表明: 低浓度熟石灰、中浓度EM菌剂及高浓度沼液处理最有利于提高西洋参产量; 施加熟石灰处理后, 土壤微生物主要类群数量显著减少, 土壤pH显著升高, 并对土壤脲酶活性有明显抑制作用; 施加沼液和EM菌剂处理后, 土壤有效微生物菌群显著增加(P<0.05), 土壤有机质和营养物质含量也显著增加(P<0.05), 并对土壤脲酶和多酚氧化酶活性有一定的促进作用。相关性分析发现, 土壤微生物主要类群的数量与蔗糖酶、脲酶、多酚氧化酶活性均有一定的相关性, 其中, 土壤细菌数量与蔗糖酶、多酚氧化酶活性呈极显著正相关(r分别为0.895^**和0.808^**), 土壤真菌和放线菌数量与蔗糖酶、脲酶、多酚氧化酶活性呈极显著正相关(r分别为0.932^**、0.769^**、0.840^**和0.837^**、0.891^**、0.797^**)。另外, 土壤细菌数量与有机质含量呈极显著正相关(r=0.863^**)。表明连作西洋参根际微生物区系及土壤酶活性与土壤理化性状之间紧密联系, 通过施加不同土壤改良剂, 可以为耐连作种植西洋参提供适宜的土壤环境。

Effects of soil amendments on rhizosphere microbial number, soil enzyme activity and yield of continuous cropped American ginseng

The continuous cropping of medicinal plants often resulted in deterioration of plant growth, decrease of plant resistibility to adversity, serious occurrence of disease and pest injury, and reduction of yield and quality. Numerous studies had found continuous copping obstacle in American ginseng cultivation, which restricted the sustainable development of American ginseng production. To explore the feasible routes of suppressing the barriers of continuous cropping of American ginseng, the paper systematically studied soil chemical properties, enzymes activities, rhizosphere microbial community and yield of continuously copped American ginseng through a randomized block experiment. Three soil amendments [hydrated lime, effective microorganisms (EM) and biogas slurry] in three application rates respectively were used in the experiment. The results showed that low-concentration of hydrated lime, middle-concentration of EM and high-concentration of biogas slurry were the most favorable conditions for American ginseng yield. The numbers of main groups of soil microorganisms and urease activity were significantly decreased, while soil pH significantly increased under hydrated lime treatments. The numbers of main groups of soil microorganisms, soil organic matter and nutrients contents were significantly improved (P < 0.05), and urease and polyphenoloxidase activities increased under biogas slurry and EM treatments. Correlation analysis showed significantly positive correlation between number of soil bacteria and activities of sucrase and polyphenoloxidase (r=0.895^**, 0.808^**). The numbers of fungi and actinomycetes were significantly and positively correlated with invertase, urease and polyphenoloxidase activities (r=0.932^**, 0.769^**, 0.840^**; 0.837^**, 0.891^**, 0.797^**). Bacteria number and soil organic matter content were significantly correlative (r=0.863^**). The results indicated that rhizosphere soil microorganisms were closely correlated with soil chemical properties, enzymes activities in continuous cropping system of American ginseng. Soil amendments in proper concentrations provided appropriate anti-continuous-cropping soil environments for American ginseng pro-duction.