草地生态系统中土壤氮素矿化影响因素的研究进展

氮素是各种植物生长和发育所需的大量营养元素之一,也是牧草从土壤吸收最多的矿质元素．土壤中的氮大部分以有机态形式存在,而植物可以直接吸收利用的是无机态氮．这些有机态氮在土壤动物和微生物的作用下。由难以被植物直接吸收利用的有机态转化为可被植物直接吸收利用的无机态的过程就是土壤氮的矿化．氮素矿化受多种因子的影响,这些因子可以归结为生物因子和非生物因子．生物因子包括：土壤动物、土壤微生物和植物种类．土壤动物可以促进土壤有机质的矿化;土壤微生物种类、结构及功能与氮的分解、矿化有密切的关系;不同的植物种类对土壤氮素的矿化作用是不相同的,一般来说。有豆科植物生长的土壤比其它种类土氮素矿化的作用大．非生物因素一般可以分为环境因子和人类活动干扰．环境因子中土壤温度和含水量对土壤氮素矿化的影响是国内外众多科学家研究的方向．尽管如此,在此方面的研究还没有取得一致意见,仍然需要进行这方面的研究,而在其他诸如：不同的土壤质地与土壤类型方面,研究报道的结论也很不一致,草地生态系统中人类活动对土壤氮素矿化的影响主要包括,不同强度的放牧,割草以及施肥、火烧强度等．非生物因子对氮素矿化的影响非常直接和明显,尤其是人类活动．本文综述了近年来影响草地生态系统土壤氮素矿化有关因素的一些进展．     

土壤食细菌线虫与细菌的相互作用及其对N,P矿化—生物固定的影响及机理

采用悉生微缩体系,研究了４０ｄ培养期内不添加外在质条件下食细菌线虫（Ｐｒｏｔｏｒｈａｂｄｔｉｓ ｓｐ．）和细菌（Ｐｓｅｕ－ｄｏｍｏｎａｓ ｓｐ．）的相互作用及其对Ｎ,Ｐ转化的影响。在种植及不种植小麦的土壤中,发现接种线虫后细菌数量显著增加,非根标土壤细菌的增加量又比根际土明显。在种植小麦体系中,根际与非根际土壤线虫均比不种作物体系有增加趋势,其中根际土壤线虫种群的提高尤为显著。只加细菌处理中土壤Ｎ     

土壤抑菌作用对食线虫真菌及其制剂的影响

通过我国东北及黄淮海地区主要大豆种植区１１种土壤对４株定殖于大豆胞囊线虫真菌淡紫拟青霉（ＰａｅｃｉｌｏｍｙｃｅｓＬｉｌａｃｉｎｕｓ）Ｍ－１４,厚垣孢子轮枝菌（Ｖｅｒｔｉｃｉｌｌｉｕｍｃｈｌａｍｙｄｏｓｐｏｒｉｕｍ）ＪＮ－１１,ＳＨ－２６和ＢＱＬ－１孢子的抑制作用及其影响因子的研究,表明土壤元菌作用普遍存在,但依土壤条件,菌种类型而异,其中以安徽宿到,济南农科院,北京,黑龙江宝泉岭农场的土壤抑菌作用     

土壤抑菌作用对食线虫真菌及其制剂的影响*

通过我国东北及黄淮海地区主要大豆种植区11种土壤对4株定殖于大豆胞囊线虫真菌淡紫拟青霉（Paecilomyceslilacimus）M-14,厚垣孢子轮枝菌（Verticilliumchlamydosporium）JN-11SH-26和BQL－1孢子的抑制作用及其影响因子的研究,表明土壤抑菌作用普遍存在,但依土壤条件、菌种类型而异,其中以安徽宿县、济南农科院、北京、黑龙江宝泉岭农场的土壤抑菌作用最强,洗涤悬液中孢子萌发率多小于30％,济南敬家、河南开封、黑龙江八五三农场等地土壤抑菌现象不明显,孢子萌发率一般在40～80％。同一土壤对4个菌株的影响是一致的。将菌种液体发酵培养,其滤液孢子萌发率一般可提高至50％以上。加入复合添加剂制得菌剂后,孢子萌发率进一步提高。土壤中微生物数量对其抑菌作用的强弱有很大影响。一般来说土壤中微生物数量越多,抑菌作用表现得也越明显。机理探讨表明土壤中存在着一些水溶性及挥发性的抑制因子,其中水溶性成分是主导因素。     

土壤食细菌线虫与细菌的相互作用及其对N、P矿化生物固定的影响及机理

采用悉生微缩体系,研究了４０ｄ 培养期内不添加外源基质条件下食细菌线虫（Ｐｒｏｔｏｒｈａｂｄｔｉｓ ｓｐ．）和细菌（Ｐｓｅｕｄｏｍ ｏｎａｓｓｐ．）的相互作用及其对Ｎ、Ｐ转化的影响。在种植及不种植小麦的土壤中,发现接种线虫后细菌数量显著增加,非根标土壤细菌的增加量又比根际土明显。在种植小麦体系中,根际与非根际土壤线虫均比不种作物体系有增加趋势,其中根际土壤线虫种群的提高尤为显著。只加细菌处理中土壤Ｎ、Ｐ均无净矿化,相反培养前期出现轻微的生物固定。线虫的引入显著提高了土壤矿质Ｎ、微生物量Ｎ 和微生物量Ｐ的含量,但对土壤有效Ｐ影响很小。这表明线虫活动主要是促进了Ｎ的矿化,而Ｐ表现出较强的生物固定。文中还分析了线虫捕食对细菌的增殖作用以及线虫——细菌相互作用在Ｎ、Ｐ矿化和生物固定中的机理。     

中国食线虫真菌的种类

对我国24个省市,涉及40余种植物的300多个土样的调查,分离出食线虫真菌近千个分离物,共鉴定出食线虫真菌29属57种,包括捕食线虫真菌4属25种,其中Arthrobotrys arthrobotryoides, A. brochopaga, A. cladodes var. macroides, A. microspora,A. musiformis, A. straminicola, Monacrosporium ellipsosporinm, M. thaumasium, M. pravicollis,Stylopage grandis, Dactylella ramiformis, Monacrosporium qiuanum, Monacrosporium sinense等10种为国内新记录。内寄生真菌4属4个种、其中Catenaria angullulae, Harposporiumarcuatum, Nematoctonus leiosporus为国内新记录。定殖于大豆孢囊线虫真菌22属25种,其中Catenaria auxiliaris, Cylindrocarpon heteronema, C. willkommii, Fusariella bizzozeriana,Nematophthora sp., Phoma eupyrena, Phoma leveilei,Pithomyces sp,Trichocladium opacum.Verticillium chlamydosporium等10属种为国内新记录,其中Nematophthora, Fusariella,Trichocladium三属为国内新记录属,Rhizoctonia sp., Stachybotrys elegans, F.bizzozeriana,C.heteronema, C.willkommii等为首次发现定殖于大豆孢囊线虫孢囊上。对所鉴定的真菌进行了描述和讨论并制作了检索表。     

食线虫真菌28S rDNA PCR扩增片段的RFLPs分析*

本文对16个食线虫真菌(节丛孢属、隔指孢属和单顶孢属)菌株和3个其他相关丝孢菌(顶辐孢属和单端孢属)菌株的28S rDNA 片段进行了扩增, 并用限制性内切酶Sau3A I, Msp I, Rsa I and Hae III对PCR产物进行了消化。采用UPGMA法对 PCR 产物的限制性图谱特征进行了聚类分析。结果表明,捕食性真菌的聚类群与捕食器官类型相对应,顶辐孢属和单端孢属与捕食性真菌的遗传距离较远。该结果与rDNA 的ITS区间、5.8S和18S的序列分析结果一致。     

食细菌线虫对热或铜胁迫下土壤功能稳定性的影响

在室内模拟重金属铜的持续胁迫或者短期加热(18 h,40℃)的瞬时胁迫条件下,以大麦叶粉短期分解过程代表土壤功能,研究了土壤食细菌线虫对土壤生态功能稳定性(抗性和恢复力)的影响.结果表明,在未施加任何胁迫对照处理中和铜胁迫条件下,食细菌线虫在一定程度上有促进土壤微生物活性的趋势.在施加铜胁迫后第15天,接种食细菌线虫导致土壤基础呼吸显著增加,并且接种食细菌线虫处理的土壤功能抗性显著高于未接种线虫处理.而在热胁迫条件下,接种食细菌线虫对土壤基础呼吸和土壤微生物活性没有显著影响,且接种食细菌线虫处理的土壤功能抗性低于未接种线虫处理.在两种胁迫条件下,接种食细菌线虫反而降低了土壤功能的恢复力.     

Effect of temperature on growth and nitrogen mineralization of fungi and fungal-feeding nematodes

Dish and column microcosms containing alfalfa-sand medium were established to determine effect of temperature on growth and N mineralization ability of two fungi (Rhizoctonia solaniand Botrytis cinerea) and two nematodes (Aphelenchus avenaeand Aphelenchoides composticola). The microcosms were incubated at 15, 20, 25 and 29 °C for 21 days. In the dish microcosms, hyphal growth rates of both fungal species increased with temperature in the range of 15–25 °C. Above that temperature range, the growth rate of R. solani remained almost constant while that of B. cinereadecrease considerably. The population growth rate of A. avenae increased with temperature between 15 and 29 °C on colonies of R. solani and B. cinerea in dish microcosms. The growth rate of A. composticola also increased in the range of 15–25 °C but decreased greatly beyond that temperature range independent of the fungal species as food source. Inorganic N (NH₄ ⁺ + NO₃ ^–) was collected from each column microcosm by leaching every 3 days. In the columns containing R. solani, there was a significant effect of temperature on the amount of N detected in the fungus+A avenaeor A. composticolabut not in the fungus alone columns. The total amount of N was greatest at 29 °C for A. avenaeand at 20 °C for A. composticola columns, concurrent with the population growth rates of the nematodes. In the columns containing B. cinerea, the effect of temperature on the amount of inorganic N was not significant in either the fungus alone or fungus+nematode columns, although the population growth rates of the both nematode species were highest at 20 °C. For B. cinerea, the N amount across temperatures was the same or larger for the fungus alone as for the fungus+nematode columns. In general, the contribution of fungal-feeding nematodes to N mineralization was small in any combinations of fungus and nematode species at any temperature. Similarity in C/N ratio of the fungal and nematode biomass, organic substrate C/N ratios too low for measurable increase in net mineralization by the nematodes and small reproduction of the nematodes in the column microcosms were probable contributory factors.     

不同土壤水分条件下华美新小杆线虫对枯草芽孢杆菌数量、活性及土壤氮素矿化的影响

采用悉生培养微缩体系,探讨了不同土壤含水量条件下,华美新小杆线虫(Caenorhabditis elegans)对枯草芽孢杆菌(Bacillus subtilis)数量和活性及土壤氮素矿化的影响.结果表明：在试验设置的不同含水量条件下,线虫对细菌的取食活动均促进了细菌的增殖 ,并明显提高了土壤呼吸强度; 不同含水量条件对细菌的增殖促进作用总体表现为23%含水量处理>17%含水量处理>28%含水量处理.线虫与细菌的相互作用显著提高了土壤铵态氮和矿质氮含量,促进了土壤氮的矿化.接种线虫对土壤氮素矿化的促进作用表现为23%含水量处理的矿质氮含量显著高于其它两个含水量处理.     

Effects of nematodes,fungi and bacteria on the growth of young apple trees grown in apple replant disease soil

Growth, dry root weight of seedlings and root score of apple seedlings cv. McIntosh were reduced when soils were inoculated with Pratylenchus penetrans, Penicillium janthinellum, Constantinella terrestris, Trichoderma sp., and 4 strains of Bacillus subtilis. Trichoderma sp., and B-1 and B-26 strains of B. subtilis alone reduced plant growth but the combination of Trichoderma sp. + B. subtilis (B-1) and Trichoderma sp. + B. subtilis (B-26) increased plant height. Plant height, root weight and root score were significantly reduced when P. penetrans plus B. subtilis or P. penetrans plus fungi plus bacteria were present in the soil. It is suggested that fungi, bacteria, nematodes alone or their combinations such as nematodes plus bacteria or nematodes plus fungi plus bacteria may contribute towards the occurrence of apple replant disease.Contribution number 700.Contribution number 700.     

镉与磷、锌、铁、钙等元素的交互作用及其生态学效应

镉是动物和植物的非必需元素 ,也是毒性最大的重金属之一。环境镉污染对植物、动物和人体均产生毒害作用。镉与许多生命必需营养元素存在着交互影响关系 ,相互影响着对方的功能发挥。镉污染胁迫可影响动植物和人体对营养元素的吸收 ,相反补充营养元素可减轻镉的毒害。但是 ,由于每个元素的性质和功能不一样 ,因此不同元素与镉的交互作用存在着差异性。镉与营养元素的交互作用研究可为生物镉污染防治提供科学依据。     

Interactions between migratory endoparasitic nematodes and arbuscular mycorrhizal fungi in perennial crops: A review

The root-lesion nematodes are important pests attacking stone and pome fruit crops throughout the world. They play an important role in the development of orchard replant problems. Host resistance toPratylenchus vulnus, the nematode of concern in mediterranean environments, has been difficult to find, and even more, to transmit into commercial rootstocks. Alternative management measures using early mycorrhizal infection that would confer protection against the nematode at a stage when plants are most vulnerable are currently being explored. These measures are considered important, taking into account a widespread change towards production systems that use in vitro material propagated in treated substrates free of mycorrhizal and other beneficial microorganisms. The prophylactic effect against root-lesion nematodes would be linked to mycorrhizal dependency of the host plant. Increase in tolerance would seem to be related to mycorrhiza assisted nutrition rather than to a direct suppressive effect of AM over the root-lesion nematode. InCitrus, Prunus, Malus andCydonia rootstocks, the nematode has shown to have a negative effect over AM colonization in the root.     

秸秆、氮肥和食细菌线虫交互作用对土壤活性碳氮和温室气体排放的影响

采用3因素2水平交互设计室内恒温培养试验,通过调控秸秆施用、氮肥用量及食细菌线虫,探讨三者对土壤微生物生物量碳氮(C_mic和N_mic)、可溶性碳氮(DOC、DON)、矿质氮(NH₄⁺-N和NO₃^--N)及温室气体排放(CO₂、N₂O和CH₄)的交互影响.结果表明： 施用秸秆显著增加了食细菌线虫数量、C_mic和N_mic,而随着氮肥用量增加,C_mic和N_mic降低,食细菌线虫对C_mic和N_mic的影响则依赖于秸秆和氮肥用量.秸秆、氮肥和食细菌线虫对可溶性碳氮和矿质氮表现出强烈的交互作用,其中秸秆和氮肥均增加了DOC、NH₄⁺ -N和NO₃^--N;食细菌线虫对DOC的抑制作用和对矿质氮的促进作用达到显著水平.秸秆处理对CO₂、N₂O的促进及对CH₄的抑制均达到显著水平,而线虫和氮肥的影响则更多表现出交互作用.在培养第56天,有秸秆时,低量氮肥下食细菌线虫显著促进了CO₂的排放,而高量氮肥下则表现出对CO₂和N₂O显著的抑制作用.总之,土壤生态功能的发挥不可忽视土壤动物的作用.     

Interactions between fungi,bacteria and beech leaves in a stream microcosm

Summary Immigration and colonization of isolates of naturally occurring stream bacteria and hyphomycetes on beech leaves were studied in a laboratory stream microcosm. Fungal spores were more successful immigrants, especially on new leaves, than bacteria, which were more repelled than attracted by the substrate. Fewer bacteria immigrated to older leaves than to new, and bacteria multiplied faster in water than on leaves. Fungi and bacteria showed synergistic relationships so that each group grew significantly faster in presence of the other group. If one considers, differences in immigration, colonization and synergism patterns, fungal mycelia doubled about 10 times faster than bacterial cells which might explain the dominance of fungi usually found on leaves in early decay. The individual fungal species could be assigned to one of three colonization groups; one of fugitive species, preceding a second group of species that grew from rarity to dominance, and a third group of very slow colonizers. The leachate was fractionated in different molecular size classes by gel chromatography, and the fraction around 2500D in the new leaf leachate was associated with a high concentration of polyphenols. High-pressure liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) revealed the presence of 16 phenolic acids in the new leaf leachate at concentrations ranging from < 1 to 640 g l^–1. All fungi except the species with the slowest growth rate grew faster on leachate with the fraction around 2500D removed, and the density of bacteria was significantly reduced when pure stream water was supplemented with compounds from the same fraction.     

Interactions between mycorrhizal fungi and other soil organisms

Mycorrhizal fungi interact with a wide range of other soil organisms, in the root, in the rhizosphere and in the bulk soil. These interactions may be inhibitory or stimulatory; some are clearly competitive, others may be mutualistic. Effects can be seen at all stages of the mycorrhizal fungal life-cycle, from spore population dynamics (predation, dispersal and germination) through root colonization to external hyphal growth. Two areas that seem likely to be of particular importance to the functioning of the symbiosis are the role of bacteria in promoting mycorrhiza formation and of soil animals in grazing the external mycelium. Mycorrhizal fungi also modify the interactions of plants with other soil organisms, both pathogens, such as root-inhabiting nematodes and fungi, and mutualists, notably nitrogen-fixing bacteria. These interactions are probably important both in natural ecosystems, where pathogens are increasingly recognized as playing controlling roles, and in agricultural systems, where mycorrhizas may be valuable in designing integrated systems of pest control and growth stimulation.     

Interactions between arbuscular mycorrhizal fungi and soil bacteria

The soil environment is interesting and complicated. There are so many interactions taking place in the soil, which determine the properties of soil as a medium for the growth and activities of plants and soil microorganisms. The soil fungi, arbuscular mycorrhiza (AM), are in mutual and beneficial symbiosis with most of the terrestrial plants. AM fungi are continuously interactive with a wide range of soil microorganisms including nonbacterial soil microorganisms, plant growth promoting rhizobacteria, mycorrhiza helper bacteria and deleterious bacteria. Their interactions can have important implications in agriculture. There are some interesting interactions between the AM fungi and soil bacteria including the binding of soil bacteria to the fungal spore, the injection of molecules by bacteria into the fungal spore, the production of volatiles by bacteria and the degradation of fungal cellular wall. Such mechanisms can affect the expression of genes in AM fungi and hence their performance and ecosystem productivity. Hence, consideration of such interactive behavior is of significance. In this review, some of the most important findings regarding the interactions between AM fungi and soil bacteria with some new insights for future research are presented.