论文部分内容阅读
主要分析了青皮天然林与木麻黄人工林等其他植被类型在土壤好气性自生固氮菌数量分布方面的差异及较强固氮能力菌株的分离和筛选。在石梅湾的8种不同植被类型样地,于不同季节取样4次,每次均取0~10 cm及10~20 cm两个土层的根际土与根外土,用改良阿须贝培养基、MPN法计数土壤好气性自生固氮菌并初步筛选具有较强固氮能力的菌株。结果表明:本区土壤好气性自生固氮菌的时间分布极不均匀,且空间分布明显受到时间的影响。从时间分布来看,在一个年周期中,4月固氮菌数量最多,而7月最少,两者差异显著,此后数量又逐渐增加;从空间分布来看,随采样时间不同,植被、取样深度、植物根系、样地地势等条件均对土壤好气性自生固氮菌数量分布也有所不同,这些条件归根到底是通过改变土壤的氮素营养供给,土壤的水、热、气条件来影响固氮菌的分布;同时各植被类型的好气性自生固氮菌数量季节变化幅度也有异,处于高级别演替阶段青皮过伐林及混交林的季节变化明显小于较低演替阶段的灌丛、次生青皮林及木麻黄林。研究还分离了15个具有潜在固氮能力的菌株,并筛选出4个固氮能力较强的菌株,为进一步在海防林的建设及青皮林的保护中研究利用植物促生菌做了初步探索和准备。
This paper mainly analyzed the differences of the number distribution of aerobic Azotobacter and the isolation and screening of strong nitrogen fixing ability strains of other vegetation types such as green peel natural wood and Casuarina equisetifolia plantation. Eight sampling plots of different vegetation types in Shimei Bay were sampled four times in different seasons, and rhizosphere soil and root soil of two soil layers of 0 ~ 10 cm and 10 ~ 20 cm each were taken. Shell culture medium and MPN method for counting aerobic Azotobacter in soil and preliminary screening of strains with stronger nitrogen fixation ability. The results showed that the temporal distribution of aerobic Azotobacter was very uneven in this area, and the spatial distribution was obviously affected by the time. In terms of time distribution, the number of nitrogen-fixing bacteria in April was the largest in April and the least in July, with significant difference between the two and the number increased thereafter. In terms of spatial distribution, with the different sampling time, vegetation, sampling depth , Plant roots, topography and other conditions on the soil aerobic autotrophic nitrogen-fixing bacteria in the number distribution is also different, these conditions in the final analysis by changing the soil nitrogen supply, soil water, heat, gas conditions to affect nitrogen-fixing bacteria The seasonal variations of aerobic azotobacter abundance varied with different vegetation types, and the seasonal changes of the number of autotrophic Azotobacter in different vegetation types were also different. The seasonal changes of the over-deforested and mixed forests in the high-level succession stages were significantly less than those in the lower succession stages. And Casuarina. The study also isolated 15 strains with potential nitrogen fixation capacity and screened 4 strains with strong nitrogen fixation capacity, which made a preliminary exploration and preparation for the further research on the use of plant growth-promoting bacteria in the construction of Haifenglin and the protection of Haifenglin .