三种湿地植物在高负荷养猪废水脱氮过程中的根际效应

为了探究不同湿地植物在处理高负荷养猪废水时的根际效应,本研究通过野外小区控制试验,以3种常见的挺水植物美人蕉(Canna indica)、梭鱼草(Pontederia cordata)、黄菖蒲(Iris pseudacorus)为研究对象构建表流人工湿地,研究人工湿地植物根系分泌物与根际氮循环微生物之间的关系。结果显示,梭鱼草对养猪废水的处理效果最好,氨氮、硝氮和总氮的去除率分别为78.3%、93.4%和81.2%。与试验前相比,梭鱼草和黄菖蒲根系可溶性有机碳(DOC)分泌速率在试验后分别增加了44.9%和13.5%;根系总有机酸(TOA)分泌速率分别增加了125.1%和147.5%。在处理养猪废水后,3种植物根际硝化过程氨氧化细菌(AOB)占主导地位,AOB-amoA基因丰度在黄菖蒲根际土中最高,为2.6×10⁸ copies·g^-1;反硝化过程nirK基因占主导地位,nirK基因丰度在梭鱼草根际土中最高,为4.3×10⁸ copies·g^-1。同时,3种植物根际均存在较明显的厌氧氨氧化过程,hz...     

Physiological and Cytological Studies on the Inhibition of Striga Seed Germination by the Plant Growth-promoting Bacterium Azospirillum brasilense

Striga hermonthica (Del.) Benth. is an obligate parasitic weed of tropical cereals whose rhizosphere can also be colonised by bacteria of the genus Azospirillum. A previous study demonstrated that the two organisms (Azospirillum and striga) interacted during cerealroot colonisation. Two strains of A. brasilense isolated from an African sorghum rhizosphere prevented the germination of striga seeds although they were stimulated to germinate by the presence of sorghum roots. Azospirillum cells suspended in a synthetic germination stimulant (GR24) did not inhibit striga seed germination, but did block radicle elongation. Those radicles had an abnormal morphology, and contained no vacuolated cells in the root elongation zone. Lipophilic compounds extracted from the medium of bacteria in the log and stationary growth phases prevented the germination of striga seeds.     

水稻化感材料的抑草作用及其机制

 水稻化感材料PI312777和化感1号在田间能显著地抑制杂草,而且其抑草作用与栽培方式相关,抛秧和移栽方式对杂草的抑制作用明显地优于直播。结果表明,PI312777和化感1号植株产生和释放的化感物质(多酚、黄酮和羟基肟酸)显著高于非化感品种华粳籼1号,而且在6叶期植株中的化感物质含量达最大值。这种不同水稻材料植株在不同生育期产生并释放化感物质量的差异是导致它们在田间抑草效应强弱的重要原因之一。进一步研究发现,PI312777植株由地上部分合成化感物质后经根部分泌到环境中,根组织并不产生化感物质,且稗草能诱导     

Research on ways to improve crop productivity through the regulation of rhizosphere environments

ABSTRACT

In this mini review, the importance of rhizosphere is focused. As the rhizosphere is underneath the soil, the analytical approach is still required from the viewpoints of understanding the interaction among root, soil and its interface. For this purpose, multi omics approach has been carried out with the effort to visualize the active rhizosphere area.     

凋落物输入对根系分泌物碳输入及土壤氮的影响

以马尾松人工林及林下灌木短柱茶为研究对象,采用根系分泌物原位收集法,分析凋落物处理[对照(保持原状凋落物不变,CK)、去除凋落物(LR)、添加凋落物(LA)]对两树种根系分泌物碳输入速率、根际土壤氮含量和氮转化相关酶活性的影响,并分析其相关关系。结果表明:凋落物输入量变化对马尾松和短柱茶根系分泌物碳输入速率无显著影响。同一凋落物处理下,马尾松和短柱茶根系分泌物碳输入速率无显著差异。凋落物输入量变化不显著影响根际土壤氮含量及马尾松根际土壤脲酶、羟胺还原酶、硝酸还原酶和亚硝酸还原酶活性,短柱茶根际土壤硝酸还原酶活性表现为去除凋落物处理显著大于对照,其余氮转化相关酶活性未表现出显著差异。可能是凋落物处理时间较短,凋落物未完全分解或者是林分年龄较大有关。相关关系结果表明,单位根长根系分泌物碳输入速率与根际土壤全氮(TN)含量呈显著负相关关系,单位根表面积根系分泌物碳输入速率与根际土壤硝态氮含量(NO-3-N)含量呈显著负相关关系。表明根系分泌物碳输入与根际土壤氮素相互影响。     

Confinement stress in sea bass (Dicentrarchus labrax) depresses peritoneal leukocyte cytotoxicity

Fish respond to stressful conditions via neuroendocrine responses (primary response) which result in increased levels of plasma cortisol which is considered immunosuppressive. Sea bass were confined at low (10 kg/m³) and high (60 kg/m³) density for 3–48 h. Plasma cortisol and glucose were evaluated and two principal cellular immune responses were assayed. A significant increase in plasma cortisol and glucose levels, as well as osmolarity, was found following stress. In addition, phagocytic activity, as shown by reactive oxygen species (ROS) production by challenged head kidney phagocytes and cytotoxic activity of eosinophilic granule cells from peritoneal cavity against K562 tumour cell lines appeared to be suppressed. Plasma levels of cortisol, glucose, osmolarity were correlated with cellular immunity, by the linear regression method. The suppression of cytotoxic activity was found to be significantly correlated with high plasma cortisol and glucose levels. These parameters could affect the eosinophilic granule cells of the peritoneal cavity.     

缺钾胁迫对连作草莓生长和土传病害的影响

 以草莓‘红颜’品种为试材,设缺K（K+ 48.75 mg · L^-1,缺量水平）、1/2K（K+ 415.58 mg · L^-1, 半量水平）和全量K（K+ 782.41 mg · L^-1,正常水平）营养液处理,对缺钾胁迫与草莓连作障碍的关系进 行了探讨。结果表明,缺钾处理显著抑制二茬草莓植株地下部分和地上部分的生长,其中缺K 的长势最 弱,1/2K 比全量K 的长势强;缺K 二茬植株根系分泌物对草莓组培苗生长有显著影响,表现为低浓度（1%、 2%）根系分泌物促进幼苗侧根和茎叶生长,高浓度（4%）则抑制根系生长。不同浓度钾营养液处理的三 茬植株分别接种尖孢镰刀菌和大丽轮枝菌后,在不同时期比未经过连作的基质对照发病都严重。缺K 三 茬植株发病最重,接菌后10 d 时病情指数就高达75,全量K 三茬植株发病次之,1/2K 三茬植株发病相 对较轻。因此,缺K 环境会加重草莓的连作障碍,适宜的K 量对草莓连作障碍的防治有重要意义。     

湿地植物根系分泌物中有机酸对NSAIDs胁迫的响应

以人工湿地典型植物芦苇（Phragmites australis）为研究对象,探索芦苇根系分泌物中有机酸对非甾体类消炎药（NSAIDs）混合物（双氯芬酸、布洛芬、吲哚美辛、酮洛芬、萘普生）长期胁迫的响应。首先,优化测定有机酸的高效液相色谱（HPLC）法;然后,构建水培和人工湿地两种体系,于NSAIDs胁迫下（地表水浓度...     

油菜、荞麦根分泌物中糖及有机酸组分的研究

利用连续流动收集系统收集了油菜、荞麦根分泌物，对介质ｐＨ变化、分泌物中碳水化合物组成及有机酸进行了测定。结果表明，荞麦、油菜生长介质中ｐＨ值变化的差异反映了它们泌质子能力的差异。在油菜分泌物中检测出高水平的鼠李糖，在荞麦中则是阿拉伯糖含量最高。草酸、琥珀酸是两种作物根分泌物的主要有机酸。苹果酸、柠檬酸在油菜根分泌物中没有检测出。     

Purification and characterization of phytase induced in tomato roots under phosphorus-deficient conditions

Phytase (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8) was purified from roots of tomato plants grown under phosphorus-deficient conditions using five purification schemes. The phytase was successfully separated from the major acid phosphatase to an electrophoretic homogeneity. The native molecular weight of this enzyme was estimated to be about 164 kD by Bio-Gel P-200 gel filtration. The molecular weight of the subunit on SDS-PAGE was approximately 82 kD, indicating that the native form of the enzyme was a homodimer. The isoelectric point of tomato phytase was about 5.5. The enzyme exhibited a high affinity for phytic acid (K _m = 38 μM), and was strongly inhibited by phosphate, molybdate and fluoride. Among other characteristics of tomato phytase, the pH and temperature optima were 4.3 and 45°C, respectively. Tomato phytase contained a fairly high concentration of aspartic, glutamic acid and glycine residues.