不同磷源对小麦根际生物活性及其根际效应的影响

通过网室盆栽和室内分析相结合的方法 ,研究了几种磷源施入石灰性土壤后对作物根际生物活性的影响。结果表明 :对于不同磷源处理 ,小麦生长过程中根际、非根际微生物种群的数量及根际效应 (R/B)有显著差异 ,其大小顺序为 :K2 HPO4>CaMg -P >SSP >FA >ck。微生物数量在生育后期达到高峰。作物根际磷酸酶活性随生育进程逐步增强。不同磷源处理影响下的土壤磷酸酶活性有一定的差异 ,总体顺序为 :FA >SSP >K2 HPO4>CaMg -P >ck。土壤碱性磷酸酶活性显著地高于中性磷酸酶活性     

松茸的地理分布与生态研究

松茸的地理分布与生态研究是人工栽培和人工促繁的基础工作,对资源的保护性开发利用具有重要的意义.介绍了松茸的名称与分类位置及其四大价值.阐述了松茸在世界和我国的地理分布;探讨了松茸的根际生态作用;分析了不同地理环境下不同种类松茸生长的独特生态条件.在此基础上提出将横断山区松茸生态研究作为今后的重点.     

香蕉根际土壤原生动物群落特征及与枯萎病病原菌的关系

香蕉枯萎病由病原真菌尖孢镰刀菌4号生理小种引起,其根际微生物组是抵御病原菌入侵的关键屏障。根际原生动物群落在根际微生物群落调控以及植物健康方面有不可忽视的作用。利用Illumina MiSeq高通量测序技术分析连作蕉园中植株发病前后根际土壤原生动物群落特征变化以及其与病原菌的相互关系。结果表明：相较于可培养细菌与真菌,原生动物的数量对病原菌的种群数量变化的影响更大;根际原生动物的群落多样性与丰富度都随植株生长而降低,且在发病植株中更低;抽蕾前后的健康与发病植株中根际原生动物群落结构存在显著差异;总体而言,吞噬型原生动物的相对丰度显著高于其他功能类型的原生动物,且在健康与发病植株中差异显著;吞噬型原生动物中与病原菌具有显著相关性的多为丝足虫门;在抽蕾期的健康植株中,丝足虫门的高丰度属中Group-Te与Cercomonas属与病原菌呈显著负相关;在抽蕾期的患病植株中,相对丰度较高的植物致病型原生动物Pythium属与病原菌呈显著正相关。综上所述,根际土壤中原生动物对病原菌的影响较大,在植株生长过程中,原生动物的群落特征发生改变,且在发病与健康植株中存在差异。与病原菌具有显著负相关的吞噬型原生动物,尤其是丝足虫门的部分高丰度属,可能会在防控香蕉枯萎病上产生一定潜力。     

Activity of nitrate reductase and the content of proteins in Nicotiana rustica grown with various levels of molybdenum

The effect that different levels of molybdenum (11 μMand 111 μM) exert on nitrate reductase (E.C. 1.6.6.1–3) activity (NRA), and the content of total proteins in Nicotiana rustica was studied. Eleven μM and 111 μM of molybdenum increased the activity of nitrate reductase during the growth cycle of N. rustica. Likewise, total protein content (mg/g DW) was increased during the vegetative growth of the plants.     

Iron Nutrition of Peanut Enhanced by Mixed Cropping with Maize: Possible Role of Root Morphology and Rhizosphere Microflora

Abstract

Field observations have indicated that Fe deficiency chlorosis symptoms in peanut are more severe and widespread in monoculture than intercropped with maize in calcareous soils of northern China. Here we report a pot experiment that investigated the mechanisms underlying the marked improvement in Fe nutrition of peanut grown in mixture with maize. Iron deficiency chlorosis occurred in the young leaves of peanut in monoculture and was particularly obvious at the flowering stage, while the young leaves of peanut grown in mixture with maize remained green throughout the experiment. The chlorophyll and HCl‐extractable Fe concentrations in young leaves of peanut grown in mixture were much higher than those in monoculture, indicating that maize may have markedly improved the peanut Fe nutrition. Growth in mixture was associated with greatly altered root morphology and microbial populations in the rhizosphere of peanut. Visual observation of peanut roots in monoculture showed that they were larger in diameter and shorter than those in mixture. Moreover, peanut roots in mixture with maize produced more lateral roots and had increased root length compared with plants in monoculture. Peanut grown together with maize showed obvious rhizodermal transfer cells in the subapical root zone, but cells with cell wall ingrowths were poorly developed in peanut in monoculture. Mixed culture resulted in a significantly decreased abundance of bacteria in the rhizosphere of peanut compared with monoculture, and electron microscope observations indicated that this was associated with a thicker mucigel layer on the root surface of peanut in mixture with maize. Several root morphological and rhizosphere microbial factors may thus have contributed to the improvement in Fe nutrition of peanut in mixed culture.     

Effects of Culture Filtrates of Rhizobacteria Isolated from Wild Lupine on Germination,Growth, and Biological Nitrogen Fixation of Lupine Seedlings

Abstract

In order to select potential Plant Growth Promoting Rhizobacteria (PGPRs), a selection of strains from the predominant genera in the rhizosphere of four lupine species, based on genetic divergence criteria, carried out in a previous study, yielded 11 Aureobacterium (Aur), four Cellulomonas (Cell), two Arthrobacter (Arth), two Pseudomonas (Ps), and six Bacillus (Bc) strains. Cell‐free culture filtrates of each bacterium were assayed for effects on germination, growth, and biological nitrogen fixation (BNF) of Lupinus albus L. cv. Multolupa seeds or seedlings. Four (Aur 6, Aur 9, Aur 11, and Cell 1) of the twenty‐five strains assayed promoted germination. Aureobacterium 6 and Aur 9 also increased root surface, total nitrogen content, and BNF. As a result of the screening, and considering all the variables studied, Aur 6 can be considered a plant growth promoting rhizobacterium and is suitable for further field trials in other plants and in different production systems.     

连作大豆根际土及根系、冠部三要素含量变化动态的研究

通过对轮、连作大豆根际土及根系、冠部氮、磷、钾三要素含量的定期测定，发现根际土中，速效氮含量连作区略高于轮作区；速效磷含量变异程度大且无规律；速效钾含量连作区低于轮作，差异达显著水平（ｔ＝４．４７８，ｔ０．０５＝４．３０３）。根系和冠部的全氮含量连作区均高于轮作区，冠部除鼓粒期外差异均达到显著水平；全磷含量鼓粒前连作区低于轮作区，盛花期差异达显著水平，鼓粒后基本无差异；全钾含量连作区均低于轮作区，差异达极显著水平（ｔ＝８．００９，ｔ０．０１＝３．１６９）。由此认为氮素不是限制连作大豆产量的因素；连作大豆快速生长期植株缺磷，应及早补施磷肥；大豆连作可导致缺钾，应增施钾肥。     

健康与罹病玉米根际微生物数量及真菌区系研究

对玉米茎基腐病植株根际微生物数量及真菌区系的研究结果表明,健康与罹病玉米植株根际微生物数量存在明显差异,其中罹病玉米植株根际真菌、细菌数量明显高于健康玉米植株,而健康与罹病玉米植株放线菌数量无明显差异。健康玉米植株根系真菌种类为8种,常见真菌3～4种,优势种的菌落数占总菌落数的28.9%～53.7%。罹病植株根系真菌种类为2～4种,仅有稀少真菌和优势种,且优势种的菌落数占其总菌落数的87.7%以上,处于绝对优势,经证明引起玉米茎基腐病的是禾谷镰刀菌。     

Resistance of bacterial communities in the potato rhizosphere to disturbance and its application to agroecology

Soil bacteria have the ability to increase agricultural sustainability through the production of biopesticides and biofertilizers. Application of bacteria to field crops often results in sporadic colonization and unpredictable crop performance. This research sought to understand the colonization of the potato (Solanum tuberosum L.) rhizosphere using reciprocal transplants. Plants were grown in a forest or an agricultural soil and then transplanted into either the same soil or the opposite soil. Bacterial communities were profiled using terminal restriction fragment length polymorphism (TRFLP) and analyzed using pairwise comparisons. The results revealed that the bacterial community that colonized the rhizosphere in the first soil remained mostly intact for 30 days after the plants were transplanted into another soil in which the soil bacteria community differed from that found in the original soil. The concept that it may be possible to establish a functional microbiota and to deliver it to an agricultural environment was tested. A nitrogen-fixing bacterial community was established on plants grown under tissue culture conditions and the plants were transplanted into a field soil. Plants inoculated with eight separate nitrogen-fixing communities showed an average fivefold increase in dry biomass when compared to mock-inoculated plants and the microbial profiles remained distinct at 30 days after transplantation. These results demonstrate that the plant rhizosphere is a resistant community and that the first bacterial community that becomes established on the root remains with the plant even when the plant is placed into soil with a vastly different microbiota.     

植物和微生物修复石油污染土壤的研究进展

阐述了植物和微生物降解环境中石油污染物及PAHs的重要作用和最新进展。国内外大量实验室研究表明,不同植物和微生物(细菌、真菌和放线菌)联合修复石油污染土壤均得到了较为理想的效果,在某种程度上微生物菌群要优于单一菌株;土壤中植物根系与微生物形成根际效应对污染物的降解起到了促进作用;生物表面活性剂较合成表面活性剂具有更好的生态适宜性和石油污染土壤修复能力;土壤中多组分污染物共同修复虽处于起步阶段,其作用机理也有待进一步研究,但是,发展前景值得期待。目前该领域的研究仍存在一些问题有待解决:植物–微生物菌群降解石油污染物过程中,微生物菌群间协同和竞争机制及试验结果的可重复性尚需证实;实验室研究与大田环境条件的差异,使得目前的研究成果尚需田间试验的验证和支持;根据土壤类型和气候特点,研究极端(高含盐量;氮、磷等营养元素缺乏;低温)条件下的石油高效降解菌株/群,制备有效的便于大田应用的固体菌肥意义重大;同时在确定石油污染物对环境致害的限值的基础上,建立石油污染土壤评价体系也势在必行。