宁夏枸杞园土壤线虫和微生物群落多样性研究

Soil Nematode and Microbial Community Diversity in Lycium barbarum L. Orchard

为了揭示宁夏枸杞园土壤质量变化趋势，以宁夏枸杞之乡——中宁县为研究区，选取不同树龄宁夏枸杞园土壤，分析不同季节、土层和树龄条件下土壤线虫和微生物群落特征变化规律。结果表明，随树龄的增加，枸杞园0～20cm土壤线虫总数先增加后减少，6a树龄时达最大值。不同树龄表层土壤均为食细菌线虫所占比例最大（夏季和秋季平均分别为57．23％和61．19％），植物寄生线虫次之；亚表层植物寄生线虫比例显著提高。夏季表层土壤总磷脂脂肪酸（PLFA）和细菌PLFA浓度随树龄呈减小一增大一减小的趋势，9a树龄各菌群PLFA浓度普遍最大。随树龄的增加，夏季0—20cm土壤线虫多样性和丰富度指数先增大后减小，但土壤微生物多样性指数、均匀度指数都逐渐减小，线虫和微生物群落优势度指数都逐渐增大；20～40cm土壤线虫和微生物数量、多样性指数和优势度指数变化趋势一致。土壤EC与微生物总PLFA浓度、细菌PLFA浓度达显著负相关；土壤有机质、全氮、速效磷含量与土壤各线虫数量和微生物浓度相关性普遍达显著或极显著水平。土壤线虫总数、食细菌线虫数量与细菌、真菌和放线菌PLFA浓度均显著或极显著相关。总之，季节、土层和树龄对土壤线虫和微生物群落均有不同程度的影响，但树龄对其影响相对最小；季节、土层和树龄对土壤微生物群落的影响比对土壤线虫群落更显著。在相同季节和土层条件下，土壤微环境质量随着树龄的增加呈现出先改善后退化的趋势。

Soil nematode and microbes are essential and very sensitive to any upsets in terrestrial ecosystems. In order to reveal the tendency of soil quality of wolfberry （Lycium barbarum L. ） orchard, make the origin of L. barbarum as the objective region, different stand ages of soil were selected in wolfberry orchard. The objective of the study was achieved by nematode and phospholipid fatty acid （PLFA） biomarker analysis of soil samples from L. barbarum orchards in the objective region. The change rule of soil nematode and microbial community diversity with the change of season, soil layer and stand age was analyzed. The results showed that the abundance of nematode was increased and then decreased in 0 - 20 cm of soil, with the highest nematode at the stand age of 6. The proportion of bacterivores was the highest （57.23% and 61.19% in summer and autumn, respectively） , and plant parasites nematode was next, fungivorous nematode and predators-omnivore had the lowest abundance. Plant parasites nematode was relatively higher at 20 -40 cm than that at 0 - 20 cm. The average concentrations of total and bacterial PLFAs in the surface soil were initially decreased and then increased, and the highest microbial PLFA concentrations were obtained in 9^th year. The tendency change of total and bacterial PLFAs were similar to nematode abundance at 20 -40 cm in summer. With longer stand age, Shannon diversity index （H＇） and richness index （SR ） of nematode were increased and then decreased, however, H＇ and SR of microbial were decreased, and dominant index was increased. The change tendency of abundance, H＇ and SR of soil nematode were similar to soil microbial. There was significant negative correlation between soil pH value, EC, microbial and bacteria PLFA. The organic matter, total nitrogen and available P were significantly positively correlated to the abundance of nematodes and concentration of microbial PLFA, respectively. Total abundance of nematode, bacterivores and bacteria, fungi and actinomyces PLFA were significantly positively correlated. On the whole, the season, layer and stand age had different effects on the nematode and microbial community, and the stand age had the least effect; the season, soil layer and stand age had more significant effect on microbe than nematode. Furthermore, the microenvironment of soil was improved and then declined gradually as the stand age increased in the same season as well as the soil layer.