宁夏枸杞根际土壤线虫群落特征

宁夏枸杞具有很高的药用价值和营养价值,在宁夏大面积种植,带来了巨大的经济效益.研究不同条件下宁夏枸杞根际土壤线虫群落特征,对防止枸杞园土壤退化具有重要意义.以宁夏枸杞之乡——中宁为研究区,系统分析了季节、树龄和土层对枸杞根际土壤线虫数量和生态指数的影响.结果表明: 夏季宁夏枸杞根际土壤线虫数量最多,小杆属和拟丽突属为优势属;春季线虫数量最少,小杆属、针属和盘旋属为优势属;从春季到秋季,线虫稀有属种类和个体密度逐渐减少.随着树龄的增加,夏季根际土壤线虫总数逐渐减少;春季和秋季枸杞根际线虫总数先增加后减少,其中9年树龄根际土壤线虫总数最多.各树龄根际均为食细菌线虫所占比例最大,食真菌线虫和捕食-杂食类线虫比例很小,树龄<3年和>9年时植物寄生线虫比例相对较大.夏季枸杞根际20～40 cm比0～20 cm土壤线虫数量增加49.4%.随着树龄的增加,枸杞根际土壤线虫多样性指数、均匀度指数和丰富度指数均呈减小-增大-减小的趋势,而优势度指数先减小后增大.土壤pH值与土壤线虫优势度指数呈显著正相关;土壤有机质和速效磷与植物寄生线虫分别呈显著正相关和负相关;土壤碱解氮与线虫总数呈显著正相关;速效钾与线虫多个生态指数均呈显著负相关.整体上,随着树龄的增加,春季和秋季土壤线虫数量先增加后减少,夏季土壤线虫数量呈逐渐减少的趋势;线虫多样性下降,土壤逐渐退化.此外,在幼林和树龄>9年后需要抑制土壤植物寄生线虫的繁殖,以减少后期因线虫引起的病害.

Soil nematode community structure in the rhizosphere of Lycium barbarum.

Lycium barbarum (Solanaceae) is an important Chinese herbal medicine and tonic species, having great contribution to local economic growth in Ningxia. It is important to study the rhizosphere nematode community structure at different conditions to prevent soil degradation of L. barbarum. The objective of this study was to determine the effect of seasonal changes, planting age and soil layers on soil nematodes community structure. The research was based on Zhongning County, where L. barbarum originated. The results showed that the abundance of soil nematode in summer was the highest and Rhabditidae and Acrobeloides were the dominant genera; the abundance of nematode in spring was significantly less than that in summer and in autumn; Rhabditidae, Pararotylenchus and Rotylenchus were the dominant genera in spring. The type and quantity of rare genera decreased gradually from spring to autumn. The abundance of nematode was increased then decreased in spring and autumn. The abundance of nematode gradually decreased with the planting age in summer. The proportion of bacterivores was the highest, and fungivorous nematodes and predators-omnivores had the lowest abundance. Plant parasites nematode was relatively higher at young and over 9-year stages. The abundance of nematode in 20-40 cm soil layer was 49.4% higher than that in 0-20 cm soil layer in summer. With the increase of planting age, Shannon diversity index (H), evenness index and richness index of nematode were in a decreased-increased-decreased pattern of change, and dominance index decreased then increased. There was significant positive correlation between soil pH and dominance index in summer. Organic matter was significantly positively correlated while available P was negatively correlated with plant parasites nematodes. Alkali-hydrolyzable N was significantly positively correlated with abundance of nematode, while available K and many nematode indexes were significantly negatively correlated. On the whole, the abundance of nematode had an increased-decreased tendency with the increasing of planting age in spring and autumn, while the abundance of nematode decreased in summer and diversity of nematode community decreased, gradually. In addition, the reproduction of plant parasites nematodes should be inhibited at young and over 9-years to ensure the L. barbarum live through the following periods.