Mycorrhizal colonization improves onion (Allium cepa L.) yield and water use efficiency under water deficit condition

Most plants benefit from mycorrhizal symbiosis through improvement of water status and nutrient uptake. A factorial experiment with complete randomized blocks design was carried out in greenhouse at Tabriz University, Iran in 2005–2006. Experimental treatments were (a) irrigation interval (7, 9 and 11 days), (b) soil condition (sterile and non-sterile) and (c) arbuscular mycorrhizal fungi (AMF) species (Glomus versiforme, Glomus intraradices, Glomus etunicatum) and non-mycorrhizal (NM) plants as control. Onion (Allium cepa L. cv. Azar-shahr) seeds were sown in sterile nursery and inoculated with fungi species. One nursery left uninoculated as control. Nine weeks old seedlings then were transplanted to the pots. Average pre-irrigation soil water contents reached to about 67, 61.6 and 57.5% of FC corresponding to 7, 9 and 11 days irrigation intervals, respectively. At onion bulb maturity stage (192 days after transplanting), yield, water use efficiency (WUE) and yield response factor (K_y) were determined. The results indicated that AMF colonization increased soil water depletion significantly. G. versiforme under both soil conditions (sterile and non-sterile) and G. etunicatum in sterile soil depleted soil water effectively (P < 0.05). Mycorrhizal fungi improved WUE significantly (P < 0.0001) in both soil conditions. It raised by G. versiforme about 2.4-fold (0.289 g mm⁻¹) in comparison with the control (0.117 g mm⁻¹). G. intraradices and G. etunicatum also had significantly higher WUE than control. Apparently water deficit in 11-day irrigation interval led to lower yield and WUE compared to 9-day interval; the later resulted highest WUE (0.254 g mm⁻¹). Mycorrhizal plants increased seasonal ET significantly due to enhancing in plant growth; G. versiforme in both sterile and non-sterile soil and G. etunicatum in sterile soil had the highest ET. Bulb yield was influenced by irrigation period and fungi species. G. versiforme produced higher yield than other treatments (135.27 g/pot). Mycorrhizal plants in 11-day irrigation interval in spite of suffering from water stress had more bulb yield than non-mycorrhizal plants in all irrigation intervals. Yield in general was higher in 9-day treatments than other irrigating internals significantly (P < 0.05). Onion yield response factor (K_y) was decreased by AMF colonization; implying that symbiosed plants become less responsive to water deficit (longer irrigation interval) compared to the control ones.     

干热河谷不同树龄攀枝花苏铁丛枝菌根真菌多样性研究

攀枝花苏铁是我国特有的古老残遗树种,为适应干热河谷气候,攀枝花苏铁与丛枝菌根真菌（arbuscular mycorrhizal fungi,AMF）建立特殊的共生体系。选用不同树龄的攀枝花苏铁为研究对象,采集攀枝花苏铁根系及根际土壤样品,采用醋酸墨水染色法观察根系的AMF定殖情况并计算定殖率;同时采用湿筛沉淀法对AMF孢子进行分离,通过形态学特征及分子生物学鉴定相结合的方法研究攀枝花苏铁AMF的种类、多样性及与树龄的关系。结果表明,14年生、8年生和3年生攀枝花苏铁根系AMF定殖率分别为36.13%、28.54%、21.10%;根际土壤AMF孢子密度分别为16.02、14.13、13.3个·g^-1,形态学鉴定到6属22种,分别为球囊霉属（Glomus）、无梗囊霉属（Acaulospora）、近明球囊霉属（Claroideoglomus）、斗管囊霉属（Funneliforms）、盾巨孢囊霉属（Scutellospora）和硬囊霉属（Sclerocystis）,球囊霉属和无梗囊霉属为优势属,相对多度分别为56.91%和28.23%。分子生物学鉴定到3属6种,分别为近明球囊霉（C.claroideum）、明球囊霉（G.clarum）、缩球囊霉（G.constrictum）、无梗囊霉属（A.srobiculata）、黑球囊霉（G.melanosporum）和地表球囊霉（G.versiforme）。统计分析表明,AMF定殖率与AMF孢子密度之间的相关性是0.873 9,呈显著的正相关关系。该研究为攀枝花苏铁的保育提供了理论依据。     

接种丛枝菌根真菌和施用磷石膏对烤烟生长及砷累积的影响

为了探讨丛枝菌根真菌（Arbuscular mycorrhizalfungi,AMF）对烤烟生长及磷石膏农用安全的影响,通过盆栽模拟试验研究了磷石膏（Phosphogypsum,PG）不同添加量[0、40mg·g^-1（PG0、PG40）1和接种两种AMF[Glomus massecle（GM）、G．aggregatum（GA）】对烤烟（KRK26）苗期生长及其磷（P）、硫（S）、砷（As）吸收的影响。试验结果表明：无论是否接种AMF,磷石膏的添加均显著增加了KRK26地上部生物量及其植株s含量、吸收量及吸收效率;除不接种处理（NM）的烤烟根系外,PG40处理显著增加了KRK26植株P含量、吸收量及吸收效率,并显著降低了NM处理的地上部As含量及吸收量,进而增加了磷砷吸收比。相同PG添加水平下,与不接种相比,接种GM和GA均显著增加了KRK26植株的生物量。除PGO处理的烤烟根系外,接种GM显著增加了KRK26植株P、S含量与吸收量及吸收效率,以及植株As含量及吸收量,并显著增加了PG40处理的植株磷砷吸收比;接种GA也显著增加了KRK26植株P、S含量及吸收量,并显著降低了PG0处理地上部As含量及吸收量。所有复合处理,以添加磷石膏40mg·g^-1和接种GA处理对KRK26的生长促进效果较好,对磷石膏施用造成的As污染有一定抵御作用。     

Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

The goal of this study was first to assess the dynamics of the bacterial community during a growing season in three Indian rain-fed wheat fields which differ mainly through their fertilizer management and yield and then to study the effects of PGPR/AMF bio-inoculations on the bacterial community structure and wheat growth. The bacterial community structure of the rhizosphere soil (RS) and the rhizoplane/endorhizosphere (RE) was determined by PCR-denaturing gradient gel electrophoresis. Seed treatments consisted of consortia of two PGPR strains alone or combined with AMF or AMF alone. The PGPR strains were Pseudomonas spp. which included some or all of the following plant growth promoting properties: phosphate solubilisation and production of indole-3-acetic acid, siderophores, 1-aminocyclopropane-1-carboxylate deaminase and diacetyl-phloroglucinol. The mycorrhizal inoculum was an indigenous AMF consortium isolated from the field with the lowest level of fertilization and yield. Variation partitioning analysis of the DGGE data indicated a predominant effect of the wheat growth stage (30.4% of the variance, P=0.001) over the type of field (9.0%, P=0.027) on the bacterial community structure in the RE. The impact of plant age in the RS was less than in the RE and the bacterial community structure of the field with the highest input of fertilization was very different from the low input fields. The bio-inoculants induced a significant modification in the bacterial community structure. In the RS, the bacterial consortia explained 28.3% (P=0.001) and the presence of AMF 10.6% (P=0.02) of the variance and the same trend was observed in the RE. Plant yield or grain quality was either increased or remained unaffected. For example, protein content was significantly higher in the treated plants' grain compared to the control plants; maximum values were obtained when the PGPR were co-inoculated with the AMF. The percentage of root colonization by AMF was significantly higher in the treatments containing a mycorrhizal inoculum than in the untreated control and remained unaffected by the PGPR treatments. In conclusion, the wheat rhizobacterial community structure is highly dynamic and influenced by different factors such as the plant's age, the fertilizer input and the type of bio-inoculant. In addition, there is a distance-related effect of the root on the bacterial community. Finally, a combined bio-inoculation of diacetyl-phloroglucinol producing PGPR strains and AMF can synergistically improve the nutritional quality of the grain without negatively affecting mycorrhizal growth.     

丛枝菌根真菌对茶树耐盐性的影响

【目的】研究盐胁迫下接种丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)对茶树根系侵染率、生长、耐盐性及茶树根际土壤酸性磷酸酶活性的影响,探索AMF提高茶树植株耐盐性的生理机理。【方法】以1年生茶树品种‘乌牛早’扦插幼苗为试验材料,采用盆栽试验,向盆土中接种丛枝菌根真菌,以接种灭菌接种物为对照,在幼苗移栽后2个月进行5,10,15,20,25,30mmol/kg 6个盐胁迫处理,分别于处理后50和100d测定茶树株高、根系菌根侵染率及叶片游离脯氨酸、丙二醛含量,100d时测定地径、主根长度、生物量、茶树叶片膜透性及根际土壤酸性磷酸酶活性,并运用模糊综合评判法对各处理的茶树生长质量进行鉴评。【结果】随着盐胁迫浓度的增加,AMF对茶树根系的侵染率逐渐降低,茶树株高、地径、生物量显著降低,生长质量下降,叶片游离脯氨酸、丙二醛含量和膜透性显著增加;与对照相比,在6个盐浓度下接种AMF后,茶树的生长量均有所增加,生长质量明显提高,叶片游离脯氨酸、丙二醛含量和膜透性均有所降低,茶树根际土壤酸性磷酸酶活性均明显提高,但其随着盐浓度的升高而下降。【结论】盐胁迫能抑制茶树的生长,而AMF可通过显著促进茶树体内渗透调节物质的积累和根际土壤酸性磷酸酶活性的提高,有效降低植株体内膜脂的过氧化水平,从而缓解盐胁迫对茶树的伤害,促进茶树在盐胁迫环境中的生长。     

5种丛枝菌根真菌对君迁子幼苗光合生长的影响

为了探明丛枝菌根真菌对君迁子生长及光合作用的影响,以分别接种了细凹无梗囊酶(Acaulospora scrobiculata,简称AS)、聚丛根孢囊酶(Rhizophagus aggregatus,简称RA)、扭形多样孢囊酶(Diversispora trotuosa,简称DT)、根内根孢囊酶(Rhizophagus intraradices,简称RI)、摩西斗管囊酶(Funneliformis mosseae,简称FM)等5种丛枝菌根真菌和未接种菌根真菌的君迁子幼苗为试材,对6种处理下君迁子幼苗的生长情况和叶片的主要光合指标进行了观测,并用双曲线修正模型对所测数据进行拟合,得到光合响应曲线及各处理下君迁子幼苗各光合特征参数。结果表明:1菌根化的君迁子幼苗其株高、地径、叶片数、植株鲜质量等指标值均有明显的提高,与未接种的对照组相比,接种AS、RA、DT、RI、FM使君迁子的株高分别提高了48.22%、62.01%、14.34%、14.66%、29.01%;其地径分别提高了22.81%、46.84%、21.19%、17.23%、14.72%;其植株鲜质量分别提高了93.69%、103.93%、53.98%、68.52%、84.44%;其单株叶片数比对照组多2~5片。2菌根化的君迁子幼苗其净光合速率、光饱和点均高于对照组,而其光补偿点则反之。3各接种处理的净光合速率的日变化趋势较为一致,均呈"双峰"曲线,12:00~14:00时均存在"午休"现象,但接种处理下君迁子幼苗叶片的净光合速率、气孔导度、蒸腾速率、水分利用率的日均值均高于对照组。研究结果表明:接种丛枝菌根真菌能够显著提高君迁子幼苗的净光合速率,改善其对光的适应性,对植株的生长有显著的促进作用,但促进作用因菌种而异。     

丛枝菌根菌丝桥传递作用对烟草抗病性相关酶活性的影响

为明确供体与受体植株间菌丝桥传递抗病信号对受体植株生长以及抗病性相关酶活性的影响,利用丛枝菌根真菌在供体与受体烟苗植株间建立菌根菌丝桥,对供体植株接种青枯菌的方法进行研究。结果表明:在供体烟苗接种丛枝菌根真菌条件下,再接种青枯菌,比只有菌丝连接的受体烟苗叶片内的过氧化物酶(peroxidase,POD)、多酚氧化酶(polyphenol oxidase,PPO)、苯丙氨酸解氨酶(phenylalanine ammonialyas,PAL)的活性分别提高了21%、29%和14%,地上部干重和植株磷含量也有相同的趋势;而在不接种丛枝菌根真菌条件下,供体烟苗接种青枯菌与否对酶的活性、植株干重及氮、磷含量均无显著影响。表明供体烟苗产生的抗病信号可以通过菌丝桥传递给受体烟苗,增强受体烟苗的抗病性。     

AM真菌对降香黄檀幼苗生长的影响

实验研究接种聚丛球霉菌(Glomuse aggrregattum)、幼套球霉菌(Glomuse etunicatum)、摩西球霉菌(Glomuse mossea)后对降香黄檀幼苗生殖生长以及营养吸收利用的影响,结果显示:1)3个菌根菌侵染效果较好,且降香黄檀幼苗对3种菌种有较强的依赖性。2)其中接种聚丛球霉菌的苗高、地茎、生物量、叶绿素含量及对营养元素N,P的吸收利用优于其他2个菌种,并与CK差异达显著水平;其苗高、地茎高于CK 44%和78%,生物量、叶绿素含量分别是CK的3.6,1.9倍,根部、茎部及叶部含N量是CK的1.47,2.03,1.34倍,而根部、茎部及叶部含P量是CK的1.53,1.47,2.09倍。     

盆栽基质对AM真菌及宿主植物生长发育的影响

在温室条件下,采用盆栽法,以摩西球囊霉(Glomus mosseae)为供试菌种,以玉米(运单19号)为供试作物,研究了不同盆栽基质(J1,J2,J3,J4和J5)对AM真菌及宿主植物生长发育的影响。结果表明,基质J1(黑石粉与壤土体积比为3∶1)对AM真菌及宿主植物生长的影响作用最大,与其他处理相比,菌根侵染率提高24.6%～114.1%,孢子含量提高12.9%～65.6%,玉米总干质量提高15.6%～109.2%,磷含量提高9.1%～84.6%。基质J3(灰石粉与壤土体积比为3∶1)对AM真菌及宿主植物的影响作用次之,基质J5(细红砂与壤土体积比为3∶1)的效果最差。此研究为优质AM菌剂生产体系的建立提供了技术参数。     

盐胁迫下丛枝菌根真菌（AMF）对紫花苜蓿生长的影响

采用盆栽受控试验法,设置无盐胁迫（0.046%）、轻度盐胁迫（0.2%）和重度盐胁迫（0.5%）3个盐分水平,研究了不同盐分下丛枝菌根真菌（arbuscular mycorrhizal fungi, amf）对紫花苜蓿（medicago sativa l.）生长量和耐盐性的影响。结果表明,随盐胁迫程度的增加,相同amf 处理的紫花苜蓿生长量显著降低（p4 hm2,约占全国盐碱地面积的6%。土壤盐渍化严重制约着农业生产,影响了资源与环境的可持续发展。紫花苜蓿（medicago sativa l.）是重要的豆科牧草,其营养、饲用价值居于各种牧草之首,同时叶片具有排盐机制,具有较强的耐盐性[1～3],在沿海滩涂地区广泛分布,是改良盐碱地的理想材料。如何利用和开发盐渍化土壤,提高盐胁迫下紫花苜蓿的耐盐性和产量日益受到重视[4～6]。