【作者】 王英；

【导师】 崔中利； 胡锋；

【作者基本信息】 南京农业大学 ， 微生物学， 2006， 硕士

【摘要】 水稻是我国主要的粮食作物，其播种面积和总产量分别占全国粮食作物的30％和45％。由于地形因素和为了获得较好的产量，水稻一般在淹水条件下种植。但是由于水资源的紧缺或地形等因素的限制，目前也有一部分地区种植旱稻。但传统的水稻淹水种植方式耗水量巨大，据估测水稻的灌溉用水量约占我国年农业用水总量的65％～80％，我国水资源短缺，水分已成为限制农业生产的最重要的因子。本研究是以江西省余江县水稻原种场的淹水和旱作稻田土壤为研究材料，利用传统的平板计数方法、MPN法以及ARDRA分子生物学技术，对淹水和旱作稻田土壤0～5、5～10和10～15cm不同深度土层中微生物的数量、部分功能群的数量以及微生物群落的多样性进行了研究。并对两种稻田土壤中的氮素、碳素、磷素循环中关键的酶，脲酶、纤维素酶、磷酸酶和一种重要的氧化还原酶类—过氧化氢酶活性作了研究，同时也对两种稻田中的产甲烷菌的多样性进行了研究。旨在为选择合理、经济的稻田耕作方式提供科学的理论依据。研究结果表明：同一稻田土壤中的微生物数量则随着土层的加深，而逐渐减少，表层土壤中微生物的数量级在10⁸，10-15 cm土层土壤中微生物的数量级在10⁷；两种稻田同层土壤中微生物的数量相比，虽然都在同一个数量级，但淹水稻田中微生物的数量高于旱作稻田中微生物的数量。部分功能群数量计数结果也表明，同一稻田中随着土层的加深，功能群的数量逐渐减少，同层土壤中功能群的数量相比，则淹水稻田中功能群的数量高于早作稻田中功能群的数量。但反硝化细菌的变化趋势除外。同一稻田土壤中，不同层的水稻土壤环境中，细菌群落结构的多样性非常丰富，但由于其多样性受土壤水分、养分、土壤层次等多种因子的影响，在不同层土壤环境中其多样性存在差异。表层土壤环境中细菌种类最丰富，多样性最高，且基因型中无明显的优势类群。淹水稻田土壤表层土壤的细菌克隆文库中525个克隆子中就有459种酶切图谱类型。旱作稻田土壤的细菌克隆文库中522个克隆子中有452种酶切类型，10～15 cm土层的细菌种类相比之下最少，但基因型中有明显的优势类群，淹水稻田土壤的底层土壤中的细菌克隆文库中507个克隆子中有372种酶切图谱类型，旱作稻田的底层土壤的细菌克隆文库中541个克隆子中有380种酶切图谱类型。在不同水分条件下，相同土层的细菌群落的多样性相比，淹水条件下的细菌的多样性高于旱作条件的细菌多样性，但差别不是很大。不同层的土壤环境间细菌群落的相似性相比，5～10 cm与10～15 cm土层的细菌群落的相似性高于0～5 cm和5～10 cm土层中的细菌群落的相似性，0～5 cm与10～15 cm土层的细菌群落的相似性很低，表明细菌群落在土壤中空间分布受到很多因素的影响，在土壤的空间分布具有很大的差异性。淹水和旱作两种稻田土壤中纤维素酶酶活性、磷酸酶酶活性和脲酶酶活性都有随着土层的加深而逐渐降低的趋势，而过氧化氢酶活性则随着土层的加深而逐渐增加。同层土壤中的酶活性相比，整体来说，淹水条件下稻田土壤中酶活性高于旱作条件下同种酶活性。通过相关性分析发现：纤维素酶活性、磷酸酶活性和脲酶活性与微生物数量和土壤肥力之间都呈正相关的关系，有的呈极显著的正相关；过氧化氢酶活性则与微生物数量和土壤肥力呈负相关；土壤中有机质含量与细菌、真菌和放线菌的数量都存在显著或极显著的正相关，全氮、有效磷和有效钾也与微生物的数量之间存在不同程度的正相关。淹水稻田土壤中产甲烷菌种群数量为8.25×10⁶cfu．g^-1干土，旱作稻田土壤中产甲烷菌种群数量为4.16×10³cfu．g^-1干土，可见淹水稻田中产甲烷菌数量明显比旱作稻田中产甲烷菌数量高；通过采用PCR-RFLP分子生物学方法来分析淹水和旱作稻田土壤中产甲烷菌种群多样性，同样酶切162个转化子，淹水稻田土壤中得到47种酶切类型，旱作稻田中得到35种酶切类型。淹水稻田产甲烷菌多样性也高于旱作稻田中产甲烷菌的多样性。更多还原

【Abstract】 Rice （Oryza sativa） is one of the main foodstuffs of Chinese people. More than 30% crop field is used for rice cultivation in China. It provides 45% of crop yields in china. Because of landform limitation and in order to obtain a better yield, rice is usually planted under flooded conditions. Owing to the lack of water resource, landform and other factors, part of rice is planted in non-flooded fieldS. But the water consumption is greatness under the conventional cultivation of rice. It is estimated that the quantity of water used for irrigation takes up 65-80 percent of the total quantity water used for farm. China is short of fresh water resource. Water is becoming the main factor that restricts the agriculture development.This research studied the microbial characteristics of the flooded and non-flooded paddy soils at rice plantation of Dengjia Town, Yujiang County, Jiangxi province. The number of microorganisms, partial of physiological function groups and the diversity of microbial communities in in 0-5、5-10 and 10-15cm depth of flooded and non-flooded paddy fields were studied based on the plate count method, MPN（most probable number） method and molecule biology method of ARDRA （amplified ribosomal DNA restriction analysis）. At the same time, the enzyme activity of key enzymes in nitrogen cycles, carbon cycles and phosphorous cycles were studied. The difference of diversity and the number of methanogen in flooded and non-flooded paddy fields were also studied. The aim of this study is to offer theoretics gist for reasonable and economical cultivation manner of rice. The main results of this study are as follows:The number of microorganism decrease with the increasing depth of Soil layers in the same paddy fields. The number of microorganism of topsoil was 10⁸, but the number of microorganisms of 10-15cm soil layers was 10⁷. The number of microorganiSm of flooded paddy fields is higher than that of the same layers soil in non-flooded paddy fields. although the number of microorganism was the same level. The results of partial functional groups counts Showed that the number of functional groups decrease with the depth of soil layers increased in the same paddy fields. The number of functional groups of flooded paddy fields is more than that of the same layers Soil in non-flooded paddy fields. But the changing trend of denitrifying bacteria was reverse compared with other functional groups.Bacteria diversity and its space distribution in 0～5、5～10 and 10～15 cm depth of flooded and non-flooded paddy fields were studied based on the molecular method of ARDRA （amplified ribosomal DNA restriction analysis）. The results indicted that in flooded paddy fields, the bacterial types were very abundance in different depth of rice soils, there were significant discrepancy in bacteria diversity among different depth of soil because of the influence of soil moisture, the soil depth, the content of carbon and other factors. Bacterial community was most abundance and showed remarkably uniform distributions, and all species were nearly equally abundant in surface soil. There were 459 kinds of OTUs in 525 clones of topsoil bacterial clones of flooded paddy fields libraries and 452 kinds of OTUs in 522 clones of topsoil bacterial clone libraries of non-flooded paddy fields.The bacteria community diversity in 10～15 cm depth soil were lower than that in surface soil, but showed dominant groups of bacterial community. There were 372 kinds of OTUs in 507 clones of 10～15 cm layer soil bacterial clone libraries of flooded rice fields and 380 kinds of OTUs in 541 clones of 10～15 cm layer soil bacterial clone libraries of non-flooded paddy fields.The comparability of bacteria community in different depth soil was very low. These results indicate that the structures of soil bacteria communities are complex. The bacterial community diversity in soil with higher water content was higher than that of paddy soil with lower water content at the same depth soil, but the discrimination was not significant.The activity of urease, phosphatases and cellulsase decreased with the soil layers increased in flooded and non-flooded paddy fields, but the catalase activity is on ther way round. As a whole, the enzymes activity in flooded paddy fields is higher than that in non-flooded paddy fields.Through correlation analysis, there were different degree positive correlation between soil enzyme activity of urease, phosphatase and cellulsase and the number of microorganism ,soil fertility; but there was a negative relation between catalase activity and the number of microorganism, soil fertility; there were also positive correlation between the number of microorganism and soil fertility to different degree.The number of methanogen was 8.25×10⁶ cfu.g^-1 dry soil in flooded paddy fields and 4.16×10³ cfu.g^-1 dry soil in non-flooded paddy fields; There were 47 kinds of OTUs in 162 clones in flooded rice fields and 35 kinds of OTUs in non-flooded rice fields based on the molecular method of PCR-RFLP. From the above data, we can concluded that the number of methanogen and the methanogen diversity in flooded paddy fields were more than those in non-flooded paddy fields.更多还原