【作者】 荆光军；

【导师】 李登煜； 朱波； 陈强；

【作者基本信息】 四川农业大学 ， 微生物学， 2007， 硕士

【摘要】 采用静态箱气相色谱法，研究了成都平原旱作农业生态系统两种不同种植模式（小麦、油菜）下，土壤N₂O和CO₂排放通量的季节变化规律及其影响因素，试验设置三种处理：（1）常规施肥处理（Nu），（2）无氮处理（N₀），（3）空闲处理（N_p常规施肥无作物）。在研究供试土样土壤酶活性、土壤微生物量碳、氮的基础上，进一步采用变性梯度凝胶电泳（DGGE）研究了不同处理土壤微生物遗传多样性的特征，以期从微观上揭示N₂O和CO₂排放的影响因素。现将实验结果分述如下。1)土壤N₂O、CO₂排放具有明显的季节变化特征，随着温度的升降和作物的生长周期变化而上下波动。油菜和小麦地常规处理土壤N₂O排放通量的变化幅度分别为0.01～0.48 mg·m^-2·h^-1和0.02～0.24 mg·m^-2·h^-1；其CO₂排放通量变化幅度分别为121.42～1585.80 mg·m^-2·h^-1和142.39-1246.19 mg·m^-2·h^-1。小麦播种和油菜移栽的初期（11、12、1月），各处理的N₂O、CO₂排放通量波动不大，日平均排放量较低，第二年开春（2、4月）后，随着温度的上升，N₂O、CO₂排放通量不断增大，到作物盛花期时，达到整个作物生长周期中N₂O、CO₂排放通量的最大值。在成熟收获阶段，N₂O、CO₂排放通量又重新回到一个较低点。2)在整个作物的生长周期内，各处理（包括无作物生长的空闲处理）的N₂O、CO₂排放通量与5 cm土壤温度在P＜0.01水平下显著正相关，呈较好的指数函数相关关系。而与土壤湿度呈负相关（R=-0.478**，P＜0.01）。土壤N₂O、CO₂排放通量，以常规处理高于无氮处理，说明氮肥施用促进了土壤N₂O、CO₂排放通量。油菜地各处理的土壤N₂O、CO₂排放通量高于小麦地相应处理，常规处理和无氮处理的土壤N₂O、CO₂排放通量高于空闲地处理，说明作物的生长促进了土壤温室气体的排放。3)DGGE技术对各土壤样品微生物多样性分析结果表明，两种不同作物种植方式下，油菜和小麦地常规处理的土壤样品细菌Shannon指数分别为1.59、1.58，空闲处理的土壤样品细菌Shannon指数分别为1.68、1.66，空闲处理土壤样品多样性指数高于常规处理；真菌多样性指数具有相同的规律。空闲地土壤具有相对较高的微生物多样性，而两种不同作物常规处理之间微生物多样性差异不明显。4)常规处理土壤微生物量碳均高于无氮处理和空闲处理，油菜地各个处理的土壤微生物量氮分别高于小麦地相对应的处理。而两种种植方式下，不同处理土壤微生物量氮高低顺序表现为：空闲处理＞常规处理＞无氮处理，表明土壤微生物量氮与土壤的有效氮含量有关。5)两种种植方式下，土壤过氧化氢酶、土壤转化酶活性高低顺序为常规处理＞无氮处理＞空闲处理；油菜地各处理土壤过氧化氢酶活性高于小麦地相对应处理，而不同作物种植方式对土壤转化酶影响不明显。空闲处理和常规处理的土壤脲酶活性均高于无氮处理土壤，土壤中施入尿素明显增大了土壤脲酶的活性。更多还原

【Abstract】 This paper dealt with the flux seasonal variation rule of nitrous dioxide and carbon dioxide by static chamber-gas chromatographic techniques in the dry-land agro-ecology in Chengdu plain. There were three kind of treatments: （1）treatment with urea（N_U）, （2） treatment without urea（N_O）, （3）treatment without crop（N_P）. Three types of soil enzyme activity and microbial biomass（C、N） were determined, furthermore the gene diversity were analyzed by the denaturing gradient gel electrophoresis （DGGE）. To reveal the relationship between N₂O、CO₂ emission fluxes and soil microbial activities, the results were reported as follows:1) The nitrous dioxide and the carbon dioxide emission fluxes had a seasonal fluctuation which related to the change of temperature. The range of N₂O emission flux in rape and wheat fields was 0.01～0.48 mg m^-2h^-1 and 0.02～0.24 mg m^-2h^-1; And the range of CO₂ emission flux was 121.42～1585.80 mg·m^-2·h^-1 and 142.39～1246.19 mg·m^-2·h^-1, respectively. The emission fluxes were at a low level and had no obviously change during the early days after the semination of wheat and transplant of rape. Following the rise of temperature in the next year,the soil N₂O、CO₂ emission fluxes kept increasing, and got to the highest value when the crops were in its florescence. During the maturity period the emission fluxes decreased to a low level.2) During the crop growth period, N₂O、CO₂ emission fluxes were positively correlated with the soil temperature at 5 cm depth but negatively correlated with the soil moisture(R=-0.478^**), and the correlations were significant at 0.01 level. N₂O、CO₂ emission fluxes were higher in the treatment N_U than those in the treatment No, which showed that fertilization improved the soil N₂O、CO₂ emission fluxes. N₂O、CO₂ emission fluxes in all the treatments of rape field were higher than those in the corresponded treatments of wheat field.3) Results of edaphon diversity by DGGE analysis of soil DNA showed that both bacteria and fungi Shannon index of treatment N_U were lower than those of treatment No, which suggested that planting crop decreased the soil microbial Shannon index. However there was no difference between the same treatments in rape and wheat fields.4) The micrbial biomass C in the treatment N_U was higher than that in the treatment N_p. The micro biomass N in all the treatments in rape field was higher than that in the corresponding treatments in wheat field. The order of microbial biomass N in both rape and wheat fields was as following: N_P＞N_U＞N_O and which demonstrated the microbial biomass N was related with the N level in soil.5) The soil enzyme activities were different in the two types of plantations and the activity of catalase and invertase in rape and wheat fields changed as following: N_U＞N_O＞N_P; Soil catalase activity in all treatments in rape field was higher than that in the corresponding treatments in wheat field. However the soil invertase activity between rape and wheat fields was at the same level, which showed that the plant did little influence to soil invertase activity. Soil urease activity in treatments N_U and N_P was higher than that in treatment N_O, so the use of urea improved soil urease activity.更多还原