土壤食细菌线虫与细菌的相互作用及其对N、P矿化生物固定的影响及机理

采用悉生微缩体系，研究了４０ｄ 培养期内不添加外源基质条件下食细菌线虫（Ｐｒｏｔｏｒｈａｂｄｔｉｓ ｓｐ．）和细菌（Ｐｓｅｕｄｏｍ ｏｎａｓｓｐ．）的相互作用及其对Ｎ、Ｐ转化的影响。在种植及不种植小麦的土壤中，发现接种线虫后细菌数量显著增加，非根标土壤细菌的增加量又比根际土明显。在种植小麦体系中，根际与非根际土壤线虫均比不种作物体系有增加趋势，其中根际土壤线虫种群的提高尤为显著。只加细菌处理中土壤Ｎ、Ｐ均无净矿化，相反培养前期出现轻微的生物固定。线虫的引入显著提高了土壤矿质Ｎ、微生物量Ｎ 和微生物量Ｐ的含量，但对土壤有效Ｐ影响很小。这表明线虫活动主要是促进了Ｎ的矿化，而Ｐ表现出较强的生物固定。文中还分析了线虫捕食对细菌的增殖作用以及线虫——细菌相互作用在Ｎ、Ｐ矿化和生物固定中的机理。

Interactions of bacterivorous nematode and bacteria and their effects on mineralization-Immobiolization of nitrogen and phosphorus

A 40 day gnotobiotic microcosm experiment without addition of exogenous substrates was conducted to investigate the interactions of the bacterial feeding nematode Protorhabditis and the bacterium Pseudomonas and the resultant influence on mineralization immobilization of nitrogen and phosphorus.It was found that the bacteria numbers significantly increased in the presence of nematode with or without winter wheat( Triticum aestivum) planting and the bacteria increment was much higher in non rhizosphere than in rhizosphere.In the microcosm with wheat the nematode numbers both in rhizosphere and in non rhizosphere seemed to be greater than those in the no plant microcosm and the nematode population increased more rapidly in the rhizosphere.In the treatment with bacteria only no net mineralized nitrogen and phosphorus were found,while slight immobilization occurred at the earlier stage of incubation.The introduction of nematode remarkably increased the soil mineral nitrogen,microbial biomass nitrogen and microbial biomass phosphorus,while it had little effect on soil available phosphorus,suggesting that the activity of nematode mainly enhances nitrogen mineralization,and strengthens the immobilization of phosphorus.The possible mechanisms involved were also discussed of the stimulation of bacteria growth by nematode grazing and of the mineralization immobilization of nitrogen and phosphorus in relation to nematode and bacterium interactions.