Effects of arbuscular mycorrhizal fungi on the growth and zinc uptake of trifoliate orange (Poncirus trifoliata) seedlings grown in low-zinc soil

The effects of the arbuscular mycorrhizal (AM) fungi, Glomus intraradices and G. versiforme, on growth and zinc (Zn) uptake were investigated in trifoliate orange (Poncirus trifoliata) seedlings exposed to low-Zn soil. Low-Zn decreased growth, levels of leaf chlorophyll, soluble protein and sugar, and soil enzymatic activities, and pH in 0–2 cm rhizosphere soil. Low-Zn soil also decreased mineral nutrients (including Zn) concentrations in the shoots and roots. Glomus intraradices especially, significantly enhanced plant biomass, leaf soluble protein and sugar concentrations, root viability, acid phosphatase, catalase, invertase and urease activities, and easily extractable glomalin content in 0–2 cm and 2–4 cm rhizosphere soil. It also increased concentrations of Zn, phosphorus, potassium and magnesium in the shoots and roots, while decreased the soil pH. Arbuscular mycorrhizal fungi, especially G. intraradices, has the potential to improve growth and Zn uptake of triofoliate orange seedlings grown in low-Zn soil.     

Effect of Inoculation with Arbuscular Mycorrhizal Fungus on Nitrogen and Phosphorus Utilization in Upland Rice-Mungbean Intercropping System

The effect of arbuscular mycorrhiza fungi （AMF） on plant growth and nutrition utilization in upland rice and mungbean intercropping system was studied. A pot experiment was conducted in the greenhouse and AMF colonization rates of rice and mungbean roots, plant nutrient contents, the ability of nitrogen fixation, and nutrient contents changed in the soil were analyzed. The results were obtained as follows： the rates of AMF colonization of rice and mungbean roots were reached to 14.47 and 92.2% in intercopping system, and increased by 4.11 and 11.95% compared with that of in monocropping; the nirtrogen contents of mungbean and rice were increased by 83.72 and 64.83% in shoots, and 53.76 and 41.29% in roots, respectively, while the contents of iron in shoot and root of mungbean were increased by 223.08 and 60.19%, respectively. In the intercropping system with inoculation of AMF, the biomass of mungbean increased by 288.8%. However, the biomass of rice was not significantly changed among all treatments with or without inoculation of AMF recorded. The number and dry weight of nodules were significantly increased either when mungbean was intercropped with rice or inoculated with AMF. When compared with that of monocropping without AMF inoculation, the contents of nitrogen, phosphorus and iron in nodules of intercropping mungbean with inoculation increased by 80.14, 69.54 and 39.62%, respectively. Additionally, intercropping with AMF inoculation significantly increased soil nitrogen content, but reduced soil phosphorus content. We concluded that upland rice-mungbean intercropping system and inoculation with AMF improved the nutrient uptake, the ability of nitrogen fixation and the growth of mungbean.     

丛枝菌根真菌对枳不同根围铁及球囊霉素螯合金属的影响

采用盆栽根袋技术,将枳根围土壤分为0-2、2-4和4-8 cm 3个水平土层,研究丛枝菌根(AM)真菌地表球囊霉对枳根围土壤中有效Fe及球囊霉素鳌合金属含量的影响.结果表明,接种AM真菌显著降低了枳根围土壤中有效Fe的含量.接种AM真菌的土壤有效Fe含量表现为:0-2 cm2-4 cm4-8 cm,而未接种的则表现为:4-8 cm2-4 cm0-2cm;枳不同根围土壤中的菌丝密度表现为:0-2 cm2-4 cm4-8 cm,表明菌丝能够穿过尼龙网伸展到4-8 cm土层中;枳不同根围土壤中易提取球囊霉素和总球囊霉素的变化规律一致,表现为:2-4 cm4-8 cm0-2 cm;土壤中球囊霉素螯合Fe和Mn的含量在4-8 cm土层中最少,螯合Zn和Cu的含量则在0-2 cm土层中最少.可见,球囊霉素能够螯合Cu等元素,减轻土壤中重金属元素对AM真菌的威胁,进而起到缓冲金属元素释放和保护真菌的作用.     

盐水胁迫下接种AM真菌对牡丹幼苗抗氧化酶活性的影响

将牡丹（Paeonia suffruticosa）幼苗接种丛枝菌根（arbuscular mycorrhizas,AM）真菌摩西球囊霉（Glomus mosseae）和地表球囊霉（G. versiforme）后,在4个不同盐水处理（质量百分比0、8%、16%和24%）下,研究AM真菌对牡丹抗氧化酶活性的影响。研究结果表明,8%盐水处理,牡丹幼苗菌根依赖性最高,且接种G. mosseae的处理显著高于接种G. versiforme的处理,分别为172%和150%;该胁迫30 d时,接种G. mosseae和G. versiforme植株干质量分别为0.51和0.45 g,叶片相对含水量分别为80.5%和78.5%,叶片超氧化物歧化酶（SOD）的活性分别为4.72 和4.46 U • g-1,过氧化物酶（POD）活性分别为60.3和57.4 U • min-1 • g-1,过氧化氢酶（CAT）活性分别为51.3和47.2 U • min-1 • g-1,均显著高于对照。16%和24%盐水处理下的表现与此相似。随盐胁迫时间的延长,SOD和CAT活性呈先升高后降低趋势,POD活性呈持续上升趋势。AM真菌通过增强牡丹幼苗抗氧化酶活性,提高其耐盐性,以G. mosseae接种效果较好。     

不同氮素形态比例条件下接种AMF对玉米氮同化关键酶的影响

以珍珠岩为基质,通过供应3种不同的NH4+∶NO3ˉ比例营养液,研究了接种丛枝菌根真菌对玉米氮同化关键酶活性的影响。结果看出,与不接种的玉米植株相比,接种Glomus intraradices和Glomus mosseae分别在NH4+∶NO3ˉ=3∶1和NH4+∶NO3ˉ=1∶3形态下提高了植物叶片的硝酸还原酶活性;接种AMF对叶片谷氨酰胺合成酶活性（GS）影响不大,但在NH4+∶NO3ˉ=3∶1形态下接种3种AMF处理均显著提高了根系GS活性,相对提高了铵态氮在地下部的同化比例。在铵态氮比例较高时,接种AMF的促生效应较好,且AMF提高根系GS活性作用较大。表明丛枝菌根真菌在促进宿主植物对铵态氮的利用作用较大。     

丛枝菌根真菌对植物抗寒性影响的研究进展

丛枝茵根真菌接种植物后,能够促进植物养分的吸收和植株的生长,提高植物的抗逆性.为了系统认识AM真菌提高植物抗寒性的机理,为植物避免冻害、南种北引、抗寒育种等提供理论依据,从AM真菌对宿主植物矿质元素吸收、形态结构、生理生化、基因表达等4个方面就国内外对丛枝菌根提高植物的抗寒性研究进行了综述.     

AM真菌在植物病虫害生物防治中的作用机制

丛枝菌根(Arbuscular Mycorrhizae,AM)真菌是一类广泛分布于土壤生态系统中的有益微生物,能与大约80%的陆生高等植物形成共生体。由土传病原物侵染引起的土传病害被植物病理学界认定为最难防治的病害之一。研究表明,AM真菌能够拮抗由真菌、线虫、细菌等病原体引起的土传性植物病害,诱导宿主植物增强对病虫害的耐/抗病性。当前,利用AM真菌开展病虫害的生物防治已经引起生态学家和植物病理学家的广泛关注。基于此,围绕AM真菌在植物病虫害生物防治中的最新研究进展,从AM真菌改变植物根系形态结构、调节次生代谢产物的合成、改善植物根际微环境、与病原微生物直接竞争入侵位点和营养分配、诱导植株体内抗病防御体系的形成等角度,探究AM真菌在植物病虫害防治中的作用机理,以期为利用AM真菌开展植物病虫害的生物防治提供理论依据,并对本领域未来的发展方向和应用前景进行展望。     

接种丛枝菌根真菌对玉米秸秆降解的影响

为研究接种丛枝菌根真菌(AMF)对玉米秸秆降解的影响,利用玉米秸秆为材料制成网袋,采用盆栽试验,以玉米(Zea mays L.)为宿主植物,分别接种Glomus intraradices和Glomus mosseae,于30,40,50,60d时收获后分析玉米秸秆降解量和C、N释放量,并运用Olson的指数模型Bt/B0=e-kt计算玉米秸秆及C、N的降解系数。数据表明,接种G.intraradices、G.mosseae显著提高了玉米秸秆降解量和降解系数,与不接种处理相比,分别高出5.21%,6.26%。C释放量、碳素降解系数也明显增加。接种处理减少了N释放量,且氮素降解系数随时间延长而下降。接种处理玉米秸秆的C、N降解系数不同直接反映了其降解速度的差异,进而影响了玉米秸秆的C/N,使秸秆更易于降解。研究结果显示出丛枝菌根真菌在生态系统氮循环中具有重要意义。     

Effect of indigenous mycorrhizal colonization on phosphorus‐acquisition efficiency in soybean and sunflower

Despite a general consent about the beneficial contribution of arbuscular mycorrhizal fungi (AMF) on natural ecosystems, there is an intense debate about their role in agricultural systems. In this work, soybean (Glycine max L.) and sunflower (Helianthus annuus L.) field plots with different P availabilities were sampled across the Pampean Region of Argentina (> 150 samples from Mollisols) to characterize the relationship between available soil P and indigenous mycorrhizal colonization. A subsequent pot experiment with soybean and sunflower was carried out to evaluate the effect of P supply (0, 12, and 52 mg P kg^–1) and AMF inoculation on AMF colonization and crop responsiveness to P in a Mollisol. Both crops showed high AMF colonization in the field (average: 55% for soybean and 44% for sunflower). While mycorrhizal colonization in soybean was significantly and negatively related to available soil P, no such trends were apparent in sunflower. Also, total biomass was 3.5 and 2.0 times higher in mycorrhizal than in nonmycorrhizal pot‐grown soybean under low‐ and medium‐P conditions, respectively. Sunflower, on the other hand, did not benefit from AMF symbiosis under medium and high P supply. While mycorrhization stimulated P‐uptake efficiency in soybean, the generally high P efficiency in sunflower was not associated with AMF symbiosis.     

Effects of benomyl on vesicular‐arbuscular mycorrhizal infection of red clover (Trifolium pratense L.) and consequences for phosphorus inflow.

The roots of red clover plants inoculated with the vesicular‐arbuscular mycorrhizal fungus Glomus clarus Nicolson & Schenck were treated with a drench of benomyl at a time when mycorrhizal infection was already well established. Benomyl halted further infection and reduced phosphorus inflow by one order of magnitude compared to untreated controls. The fungicide also decreased the rate of plant growth probably as a consequence of reduced phosphorus inflow.