连续施钼对土壤微生物多样性及化学计量特征的影响

发布时间：2019-04-01 06:26

【摘要】：钼是植物、动物和微生物必需的微量元素,以往的研究多关注钼在植物体内的生理功能,然而钼对土壤微生物多样性及土壤碳氮磷循环过程的影响尚不清楚。本论文通过长期定位试验田研究连续施钼对土壤微生物多样性及其驱动的土壤碳氮磷循环过程的影响,以探明施钼影响碳氮磷循环的微生物机制。获得的主要结果如下:1.连续施钼影响了番茄成熟期根区土壤细菌的多样性、种群相对丰度及相关功能基因的丰度。连续施钼(+Mo)显著降低了番茄成熟期根区土壤细菌的Chao1、ACE以及Shannon指数,但增加了优势菌门中放线菌门、酸杆菌门、绿弯菌门等所占比例,降低了变形菌门等细菌所占比例。连续施钼显著增加了番茄根区土壤Myroides、Lysinibacillus、Pseudomonas等6个菌属相对丰度,显著降低了Spingomonas、Nitrospira、Rhodoplanes等9个菌属的相对丰度,而这些细菌中部分种群参与了土壤中纤维素降解、解磷、固氮、硝化等过程。从基因功能分类上看,连续施钼显著增加了番茄根区土壤细菌中与光合作用、碱基修复相关的基因丰度,显著降低了脂肪酸合成等相关基因的丰度。2.连续施钼影响了小麦和蚕豆根区土壤碳、氮、磷库特征及动态变化。连续施钼对小麦和蚕豆根区土壤碳库组成(总有机碳、活性有机碳、中活性有机碳和高活性有机碳)影响不显著,但有增加蚕豆根区土壤β-葡糖苷酶(βG)活性的趋势;连续施钼对小麦、蚕豆根区土壤各氮组分(全氮、硝态氮和铵态氮)影响不显著,但显著降低了小麦分蘖期N-乙酰氨基葡糖苷酶(NAG)活性;连续施钼对小麦和蚕豆根区土壤全磷、速效磷及各种磷组分影响不显著,但显著增加了蚕豆和小麦苗期根区土壤活性磷库的容量。缺钼条件下,根区土壤中铵态氮、硝态氮含量与土壤碳组分呈显著负相关,与土壤磷组分及酸性磷酸酶活性呈显著负相关,说明缺钼条件下根区土壤氮循环与碳循环、氮循环与磷循环之间存在不平衡,而施钼条件下这种矛盾不突出。3.连续施钼对蚕豆和小麦根区土壤C/N、N/P、C/P等生态化学计量特征的响应不敏感。随着生育期的推进,小麦和蚕豆根区土壤涉碳生态酶lnβG和涉磷生态酶lnACP的比值、涉氮生态酶lnNAG和涉磷生态酶lnACP的比值均呈上升趋势,连续施钼增加了蚕豆幼苗期根区土壤lnβG:lnACP和lnNAG:lnACP。
[Abstract]:Molybdenum is an essential trace element for plants, animals and microorganisms. Previous studies have focused on the physiological function of molybdenum in plants. However, the effects of molybdenum on soil microbial diversity and soil C, N and P cycle are still unclear. In this paper, the effects of continuous application of molybdenum on soil microbial diversity and soil carbon, nitrogen and phosphorus cycling process were studied in a long-term targeted field, in order to find out the microbial mechanism of the effect of molybdenum application on carbon, nitrogen and phosphorus cycles. The main results obtained are as follows: 1. Continuous application of molybdenum affected the diversity of soil bacteria, the relative abundance of population and the abundance of related functional genes in the root zone of tomato at maturity stage. Continuous application of molybdenum (Mo) significantly decreased the Chao1,ACE and Shannon index of soil bacteria in the root zone of tomato at maturity stage, but increased the proportion of actinomycetes, acidobacteria and chlorobacteria in dominant fungi, and decreased the proportion of bacteria such as deformable fungi. The continuous application of molybdenum significantly increased the relative abundance of six mycorrhizal genera, such as Myroides,Lysinibacillus,Pseudomonas, and decreased the relative abundance of 9 genera, such as Spingomonas,Nitrospira,Rhodoplanes, in the soil of tomato root zone, and some of these bacteria took part in the degradation of cellulose and phosphorus degradation in the soil. Nitrogen fixation, nitrification, etc. In terms of gene functional classification, continuous application of molybdenum significantly increased the abundance of genes related to photosynthesis and base repair in soil bacteria in tomato root zone, and significantly decreased the abundance of genes related to fatty acid synthesis. 2. Continuous application of molybdenum affected the characteristics and dynamic changes of soil carbon, nitrogen and phosphorus pools in the root zone of wheat and broad bean. The effects of continuous application of molybdenum on the composition of soil carbon pool (total organic carbon, active organic carbon, middle active organic carbon and high active organic carbon) in the root zone of wheat and broad bean were not significant, but there was a tendency to increase the activity of 尾-glucosidase (尾-G) in the soil of the root zone of Vicia faba. The N-acetylglucosaminidase (NAG) activity in wheat and Vicia faba root zone was not significantly affected by the continuous application of molybdenum, but the activity of N-acetylglucosaminidase (NAG) was significantly decreased at tillering stage. Continuous application of molybdenum had no significant effect on soil total phosphorus, available phosphorus and various phosphorus components in root zone of wheat and broad bean, but significantly increased the capacity of soil active phosphorus pool in root zone of broad bean and wheat at seedling stage. Under the condition of molybdenum deficiency, the contents of ammonium nitrogen and nitrate nitrogen in root zone soil were negatively correlated with soil carbon component, and negatively correlated with soil phosphorus component and acid phosphatase activity, indicating that soil nitrogen cycle and carbon cycle in root zone under molybdenum deficiency condition. There is an imbalance between the nitrogen cycle and the phosphorus cycle, but this contradiction is not prominent under the condition of molybdenum application. 3. Continuous application of molybdenum was not sensitive to eco-stoichiometric characteristics of broad bean and wheat root zone soil, such as C _ (N), N ~ (P), C ~ (?) P, etc. With the advance of growth period, the ratio of ln 尾 G, lnACP, lnNAG and lnACP in wheat and Vicia faba root zone increased, and the ratio of soil carbon-related ecological enzyme lnNAG 尾 G and phosphorus-related eco-enzyme lnACP in wheat and Vicia faba root zone showed an increasing trend. Continuous application of molybdenum increased Ln 尾 G: lnACP and lnNAG:lnACP. in root zone of Vicia faba L. at seedling stage.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.3;S153

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