接种菌根真菌对梨幼苗养分吸收与生长发育的影响

试验采用川梨（Pyrus pashia Buch.-Ham.）实生幼苗为材料,盆栽条件下,接种丛枝菌根真菌根内球囊霉Glomus intraradices（GI）、摩西球囊霉Glomus mosseae（GM）和地表球囊霉Glomus versiforme（GV）,从而研究接种菌根真菌对梨根系活力及发育的影响。结果表明,试验所采用的3种丛枝菌根真菌均能有效地侵染川梨实生苗,接种GI的菌根侵染率显著高于接种GM和GV,接种GI的菌根效应最佳,是侵染川梨根系的优势菌根真菌,菌根对根系最长侧根长、一级新根数和根体积都有明显提高,最大分别提高了16.3%、6%和13.9%,接种菌根真菌显著地提高川梨根系活力,增加根可溶性蛋白含量,并显著促进了幼苗植株的矿质营养水平。     

干旱胁迫下AMF对葡萄扦插苗生长及养分吸收的影响

为研究干旱胁迫下丛枝菌根（arbuscular mycorrhiza, AM）真菌对葡萄扦插苗生长及养分吸收的影响。本试验采用双因素试验设计,在正常水分（well-watered, WW）和干旱胁迫（drought stress, DS）下研究接种和不接种摩西管柄囊霉（Funneliformis mosseae）对“夏黑”葡萄扦插苗地上部的生长、根系构型和养分吸收的影响。结果表明,干旱胁迫显著降低了葡萄扦插苗根系菌根侵染率,抑制了不定根的发生,阻碍了根系构型的建立,进而影响了葡萄扦插苗的生长。但无论是DS还是WW条件下,接种AMF都显著增加了葡萄扦插苗地上部的生物量,促进了不定根的发生,表现出更好的根系构型参数。此外,接种AMF后还显著提高了葡萄扦插苗叶片和根系矿质元素的含量。因此,AMF能够通过促进葡萄不定根的发生、改善根系构型、促进养分吸收,进而作用于地上部的生长与形态构建,使扦插的葡萄幼苗生长更佳。     

减量施肥下AMF对盆栽柑橘生长及土壤酶活性的影响

为研究减量施肥下丛枝菌根真菌（AMF）对柑橘幼苗生长的影响,采用盆栽试验,研究3个施肥水平（习惯施肥、减量30%施肥和减量60%施肥）和接种AMF（摩西斗管囊霉）对大雅柑/香橙脱毒苗生长、土壤养分积累和酶活性的影响。结果表明：相同施肥水平下,接种AMF后均促进了柑橘幼苗生长、土壤养分积累和酶活性。未接种条件下,减量30%施肥不会影响柑橘幼苗的生长,但是减量60%施肥明显抑制了柑橘幼苗生长;接种处理后,减量30%施肥水平下柑橘幼苗生长最好,但减量60%施肥水平下柑橘幼苗的接种效应最高。因此,在当前习惯施肥水平下适当减少氮磷钾用量不会影响柑橘幼苗的生长,接种AMF后适当减少氮磷钾肥施用量还能促进柑橘幼苗的生长、改善土壤养分过量累积和提高土壤养分利用率。     

AMF对铅锌矿区农田土壤部分理化性质、玉米生长和镉铅含量的影响

为研究重金属污染胁迫下丛枝菌根真菌（Arbuscular mycorrhizal fungi,AMF）对土壤部分理化性质、玉米生长、光合生理、养分与镉铅含量的影响,以云南会泽、兰坪铅锌矿区周边重金属污染农田土壤为供试土壤,玉米为宿主植物,设置接种和不接种AMF处理,开展室内盆栽试验。结果表明：接种AMF显著增加土壤易提取球囊霉素相关蛋白（EE-GRSP）与总球囊霉素相关蛋白（T-GRSP）的含量;降低土壤有效态镉、铅含量,降幅为34.6%~79.5%;增加土壤中碱解氮和速效磷的含量,增幅为30.9%~206%。接种AMF显著增加玉米植株氮磷养分含量,增幅为17.6%~38.5%;增强叶片光合作用,提高植株生物量;降低植株镉铅含量,降幅达30.0%~68.7%。相关性分析发现,土壤T-GRSP与碱解氮、速效磷含量呈极显著正相关;EE-GRSP、T-GRSP与有效态铅含量呈显著负相关;玉米植株镉、铅含量与土壤有效态镉、铅含量呈显著正相关;玉米根系氮与土壤碱解氮含量、植株磷与土壤速效磷含量呈显著正相关。研究表明,接种AMF增加土壤球囊霉素相关蛋白含量,降低污染土壤镉、铅生物有效性,减少玉米植株镉、铅的含量;增加土壤速效养分含量,改善玉米矿质营养和光合生理,提高玉米植株生物量。     

丛枝菌根真菌对白刺花苗期抗旱酶系及生理特性的影响

为探究丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)促进植物抗旱性机制。以盘江白刺花为材料,采用盆栽试验,研究摩西球囊霉、幼套球囊霉、根内球囊霉3种丛枝菌根真菌对白刺花苗期抗旱酶系及生理指标的影响,并综合分析评价AMF接种的最佳方案。结果表明：接种不同浓度AMF菌株对白刺花幼苗的抗旱性影响不同,当接种40%根内球囊霉菌,过氧化氢酶(CAT)和过氧化物酶(POD)活均显著高于对照(P<0.05);接种40%幼套球囊霉菌时,超氧化物歧化酶(SOD)和谷胱甘肽S-移换酶(GST)活均显著高于对照(P<0.05),淀粉含量增加58.2%;接种40%摩西球囊霉菌时,可溶性糖含量提高了25.3%;接种20%根内球囊霉菌时,纤维素含量增加45.5%;当接种20%幼套球囊霉菌时,丙二醛(MDA)含量显著高于对照(P<0.05)。相关性分析表明白刺花抗旱指标淀粉、CAT、GST、POD和SOD相互之间呈极显著正相关,与MDA呈极显著负相关;主成分分析将8个耐旱相关指标分为2个主成分,累计贡献率达76.50%;结合隶属函数分析表明,3种AMF对白刺花幼...     

Responses of wheat to arbuscular mycorrhizal fungi: A meta-analysis of field studies from 1975 to 2013

Arbuscular mycorrhizal fungi (AMF) can benefit growth and yield of agriculturally significant crops by increasing mineral nutrient uptake, disease resistance and drought tolerance of plants. We conducted a meta-analysis of 38 published field trials with 333 observations to determine the effects of inoculation and root colonization by inoculated and non-inoculated (resident) AMF on P, N and Zn uptake, growth and grain yield of wheat. Field AMF inoculation increased aboveground biomass, grain yield, harvest index, aboveground biomass P concentration and content, straw P content, aboveground biomass N concentration and content, grain N content and grain Zn concentration. Grain yield was positively correlated with root AMF colonization rate, whereas straw biomass was negatively correlated. The most important drivers of wheat growth response to AMF were organic matter concentration, pH, total N and available P concentration, and texture of soil, as well as climate and the AMF species inoculated. Analysis showed that AMF inoculation of wheat in field conditions can be an effective agronomic practice, although its economic profitability should still be addressed for large-scale applications in sustainable cropping systems.     

The influence of tillage on the structure of rhizosphere and root-associated arbuscular mycorrhizal fungal communities

Soil environmental factors affect the structure of arbuscular mycorrhizal (AM) fungal communities present in soil. However, it is not understood to which degree management practices such as tillage lead to dissimilarities between intra- and extraradical AM fungal communities. This study aims to assess the influence of two different soil management practices (conventional tillage and no-till) on the diversity of AMF communities, both in rhizosphere soil and inside corn roots. We hypothesized that under no-till, roots are colonized as they grow through the undisturbed fungal mycelia left from the previous crop whereas under conventional tillage they are colonized by those propagules that survived disturbance and can re-establish in their new relocated and mixed environment. We predicted that the degree of similarity of AM fungal communities inside versus outside the roots would be greater under no-till than under tillage. Using terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis we observed a different AM fungal community present in roots under no-till than under conventional tillage. Moreover, the communities present in the rhizosphere soil were different than in the roots of the corn plants. These results suggest that soil management does alter the diversity of AM fungal communities associated with corn roots and that plants influence the structure of the AMF community colonizing their roots. Sequencing results indicated that the majority of AMF species found in this agricultural soil was Glomus spp. However, further work is required to determine the extent to which AM fungal genotypic alterations by soil management influences competitive relationships.     

Direct, positive feedbacks produce instability in models of interrelationships among soil structure, plants and arbuscular mycorrhizal fungi

Current conceptual models of reciprocal interactions linking soil structure, plants and arbuscular mycorrhizal fungi emphasise positive feedbacks among the components of the system. However, dynamical systems with high dimensionality and several positive feedbacks (i.e. mutualism) are prone to instability. Further, organisms such as arbuscular mycorrhizal fungi (AMF) are obligate biotrophs of plants and are considered major biological agents in soil aggregate stabilization. With these considerations in mind, we developed dynamical models of soil ecosystems that reflect the main features of current conceptual models and empirical data, especially positive feedbacks and linear interactions among plants, AMF and the component of soil structure dependent on aggregates. We found that systems become increasingly unstable the more positive effects with Type I functional response (i.e., the growth rate of a mutualist is modified by the density of its partner through linear proportionality) are added to the model, to the point that increasing the realism of models by adding linear effects produces the most unstable systems. The present theoretical analysis thus offers a framework for modelling and suggests new directions for experimental studies on the interrelationship between soil structure, plants and AMF. Non-linearity in functional responses, spatial and temporal heterogeneity, and indirect effects can be invoked on a theoretical basis and experimentally tested in laboratory and field experiments in order to account for and buffer the local instability of the simplest of current scenarios. This first model presented here may generate interest in more explicitly representing the role of biota in soil physical structure, a phenomenon that is typically viewed in a more process- and management-focused context.     

Differences of hyphal and soil phosphatase activities in drought-stressed mycorrhizal trifoliate orange (Poncirus trifoliata) seedlings

Differences of hyphal and soil phosphatase activities between mycorrhizal and non-mycorrhizal plants were less studied under drought-stressed (DS) conditions. In a pot experiment, fungal alkaline phosphatase (FALP), and succinate dehydrogenase (FSDH), soil phosphatase activity, both soil and plant P contents were compared in 6.5-month-old trifoliate orange (Poncirus trifoliata) seedlings under 80 days of DS with or without inoculations by arbuscular mycorrhizal fungi (AMF, Glomus diaphanum, Glomus mosseae or Glomus versiforme). Plant growth and biomass production under DS were significantly higher in mycorrhizal than in non-mycorrhizal seedlings. Both the FALP and the FSDH activities under DS were significantly reduced in these three Glomus inoculated seedlings. In general, similar soil neutral and alkaline phosphatase activities, but significantly higher soil acid and total phosphatase activities, were exhibited in mycorrhizal than in non-mycorrhizal seedlings under both the well-watered (WW) and the DS. Both leaf and root P contents were significantly higher in the AM colonized seedlings, but soil available P contents were lower in the growth media with AM seedlings. Our results showed that higher hyphal enzymes’ activities, soil acid and total phosphatase activities, and plant P contents in AM colonized seedlings, particularly in Glomus mosseae-colonized seedlings and/or under DS, would result in a better growth of the host plants, which might be the basis for enhancing drought tolerance in plants.     

Response of Different Crops to Arbuscular Mycorrhiza Fungal Inoculation in Phosphorus-Deficient Soil

Arbuscular mycorrhizal fungi (AMF) have the capability to improve crop yields by increasing plant nutrient supply. A pot experiment was conducted under natural conditions to determine the response of AMF inoculation on the growth of maize (Zea mays L.), sorghum (Sorghum bicolor L.), millet (Pennisetum glaucum L.), mash bean (Vigna mungo L.), and mung bean (Vigna radiata. L.) crops during 2008. The experiment was conducted as a completely randomized design in three replications using phosphorus (P)–deficient soil. Three plants were grown in 10 kg soil up to the stage of maximum growth for 70 days. Spores of AMF were isolated from rhizosphere of freshly growing wheat and berseem crops and mixed with sterilized soil with fine particles. Crops were inoculated in the presence of indigenous mycorrhiza with the inoculum containing 20 g sterilized soil mixed with 40–50 AMF spores. Inoculation with AMF improved yield and nutrient uptake by different crops significantly over uninoculated crops. Inoculated millet crop showed 20% increase in shoot dry matter and 21% in root dry matter when compared with other inoculated crops. Increases of 67% in plant nitrogen (N) and iron (Fe) were observed in millet, 166% in plant P uptake was observed in mash beans, 186% in zinc (Zn) was measured in maize, and 208% in copper (Cu) and 48% in manganese (Mn) were noted in sorghum crops. Maximum root infection intensity of 35% by AMF and their soil spore density were observed in millet crop followed by 32% in mash beans. Results suggest that inoculation of AMF may play a role in improving crop production and the varied response of different crops to fungi signifies the importance of evaluating the compatibility of the fungi and plant host species.