紫色土区不同秸秆还田量对土壤线虫群落的影响

为了研究不同秸秆还田量对紫色土区土壤线虫群落的影响, 作者于2011年5月和9月对川中丘陵区的100% (RMW1)、50%(RMW2)、30%(RMW3)和空白对照(CK)4种秸秆还田量的农田土壤线虫进行了调查。结果发现, 随着秸秆还田量的下降, 土壤线虫的群落结构有一定变化。总体上, 群落密度、食真菌类群和捕食-杂食类群的密度呈波动增加; 食细菌类群的密度持续增加; 植物寄生类群密度、Shannon-Wiener多样性指数(H')、植物寄生成熟指数(PPI)和瓦斯乐斯卡指数(WI)呈先增加后下降的变化趋势, 且多样性指数在秸秆还田量为30-50%之间最高; 类群数、自由生活成熟指数(MI)、线虫通路比值(CR)则先下降后增加; 所有变化均不显著(P > 0.05)。土壤速效钾含量随秸秆还田量的增加显著提高(P < 0.05), 且与线虫群落多样性指数呈显著负相关(P < 0.05)。研究结果表明, 在紫色土区秸秆还田主要是通过改变土壤钾含量对土壤线虫群落产生影响, 且秸秆还田量在30-50%之间时有利于维持线虫群落多样性。

Effects of different amounts of straw returning treatments on soil nematode community in purple soil

We evaluated the effects of 4 years of straw returning (2007-2011) on the nematode communities of the purple soil area in the hilly areas of central Sichuan basin, China, using the four treatments of 100, 50, 30, and 0% of straw returned to cropland. The Baermann method was used to extract nematodes from soil samples (0-15 cm). A total of 2,380 individuals, belonging to 2 classes, 8 orders, 24 families, and 39 genera, were extracted. The dominant genera included Tylencholaimus and Prionchulus, comprising 31% of total soil nematode individuals. Our results showed that soil nematode communities differed among the four treatments. Densities of the total nematode community, and fungivores and predators-omnivores specifically exhibited greater fluctuations with reducing straw return levels, while densities of bacterivores increased with reducing straw levels. Plant-parasite density, diversity index(H'), plant-parasite index (PPI) and Wasilewska index (WI) first increased and then decreased with reduction of straw return, while genera number, free-living nematode maturity index (MI) and channel ratio (CR) presented the opposite trend. Nematode diversity index (H') was highest at 30-50% straw return levels. But there were no significant differences among treatments for all of the indexes. The content of soil available potassium, which significantly increased at the lower levels of straw return, was significantly correlated with diversity indices of nematode communities. Our results suggested that straw return management changes the nematode community through its action on the content of soil available potassium, and that level of 30-50% of straw returning were optimal in the hilly areas of central Sichuan basin in terms of maximizing nematode diversity.