土壤压实胁迫下丛枝菌根真菌对高羊茅生理生态的影响

该试验设计4种土壤压实处理[土壤容重分别为1.2(CK_1)、1.3、1.4和1.5 g·cm~(-3)],并与压实处理前分别接种2种丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)——摩西斗管囊霉(Funneliformis mosseae,Fm)和根内根孢囊霉(Rhizophagus intraradices,Ri)组成的4个接种处理[Fm、Ri、Fm+Ri和不接种(CK_2)],共组成16个处理,分析不同处理对高羊茅(Festuca elata)品种‘艾瑞3号’的生理生态指标的影响,为AMF在压实土壤中的应用提供理论基础。结果表明:(1)高羊茅根系的菌根侵染率和菌丝密度均随土壤容重的增加而逐渐降低;与CK_1相比,在土壤容重1.5 g·cm~(-3)处理下接种Fm、Ri、Fm+Ri的高羊茅根系菌根侵染率分别显著降低了27.8%、39.8%和30.0%,菌丝密度分别显著降低43.8%、42.1%和43.8%,且在1.5 g·cm~(-3)土壤容重下,接种Fm+Ri处理的菌根侵染率和菌丝密度比单接种Fm分别提高17.3%和25.2%,比单接种Ri处理分别提高53.0%和36.3%。(2)接种AMF能有效增加土壤压实胁迫下高羊茅植株的株高、分蘖数和干物质质量,显著提高高羊茅耐受力,接种Fm+Ri处理的株高、分蘖数及干物质质量在1.5 g·cm~(-3)土壤容重下分别比未接种(CK_2)显著增加36.1%、39.5%和144.0%。(3)接种AMF能显著提高土壤压实胁迫下高羊茅根系活力以及过氧化氢酶(CAT)活性,接种Fm+Ri处理的根系活力以及CAT活性在1.5 g·cm~(-3)土壤容重下分别是对照(CK_2)的1.4和1.5倍。(4)接种AMF能显著提高土壤压实胁迫下高羊茅叶绿素a、b以及总叶绿素含量,接种Fm+Ri处理在1.5 g·cm~(-3)土壤容重下比对照(CK_2)的上升幅度分别提高43.1%、100.0%和59.3%。(5)接种AMF能显著提高土壤压实胁迫下高羊茅叶片净光合速率(P_n)、蒸腾速率(T_r)以及气孔导度(G_s),显著降低其叶片胞间CO_2浓度(C_i),接种Fm+Ri处理在1.5 g·cm~(-3)土壤容重下比对照(CK_2)的升降幅度分别为52.5%、33.3%、181.1%和-32.9%。综上所述,土壤压实胁迫显著抑制AMF的侵染,而共同接种Fm+Ri能显著促进AMF对根系的侵染,且共同接种处理的效果明显优于单一接种;AMF可通过增强高羊茅根系活力、降低氧化胁迫造成的伤害、提高植物叶绿素含量与光合作用来增强自身的抗土壤压实能力。     

矿区分离丛枝菌根真菌对万寿菊吸Cd潜力影响

盆栽试验研究土壤不同施Cd水平(0、5、20、50μg/g)下,接种矿区污染土壤中丛枝菌根真菌对万寿菊根系侵染率、植株生物量及Cd吸收与分配的影响。结果表明:接种丛枝菌根真菌显著提高Cd胁迫下万寿菊的根系侵染率和植株生物量;随着施Cd水平提高,各处理植株Cd浓度显著增加。各施Cd水平下万寿菊地上部Cd吸收量远远高于根系Cd吸收量,在土壤施Cd量达到50μg/g时,接种处理地上部Cd吸收量是根系的3.48倍,对照处理地上部Cd吸收量是根系的1.67倍;同一施Cd水平下接种处理植株Cd吸收量要显著高于对照。总体上,试验条件下污染土壤中分离的丛枝菌根真菌促进了万寿菊对土壤中Cd的吸收,并在一定程度上增加Cd向地上部分的运转,表现出植物提取的应用潜力。     

空气断根对侧柏实生苗生物量分配和根系生长的影响

为探求林木幼苗生物量分配和根系生长对空气断根的响应,以侧柏(Platycladus Orientalis)实生苗为材料,设置空气断根(T)和不断根(CK)处理,研究了空气断根10、30 d和50 d后对侧柏生物量、根系形态特征及吸收面积的影响。结果表明:(1)T处理的侧柏幼苗地上生物量、根生物量、总生物量、根长、根表面积、根体积及根尖数在断根10、30 d和50 d后均大于CK,且显著扩大了根系总吸收面积和活跃吸收面积。(2)空气断根显著影响了侧柏实生苗的生物量分配格局,其根冠比在整个试验阶段呈先增大后减小的趋势,而CK逐渐减小。(3)两种处理的侧柏幼苗根系直径集中在0-0.5 mm。与CK相比,T处理侧柏随空气断根时间延长,单株根系直径在0-0.5 mm的根数量急剧增多,占总根尖数的79%,根平均长度、根表面积、根体积和根尖数显著增大。(4)生物量参数和根形态参数之间关系密切。根生物量与地上生物量及总生物量呈显著正相关(P0.05)。除根系平均直径外,根生物量、地上生物量和总生物量分别与根长、根表面积、根体积、根尖数呈显著正相关,根冠比与地上生物量呈负相关。因此,空气断根有效改善了侧柏幼苗的根系形态特征,提高了吸收面积,显著促进侧柏实生苗在生长早期快速发育。     

丛枝菌根真菌对枳根系形态和蔗糖、葡萄糖含量的影响

研究丛枝菌根真菌接种(摩西球囊霉、地表球囊霉和摩西球囊霉+地表球囊霉)对盆栽枳的生长、根系形态以及蔗糖、葡萄糖含量的影响.结果表明: 3个接种处理都显著提高枳的株高、茎粗、叶片数,以及地上部和地下部生物量,诱导1级、2级和3级侧根的发生,同时增加了根系投影面积、表面积、体积和总长度(主要是0～1 cm根长),但降低根系平均直径,其中以地表球囊霉效果最明显.丛枝菌根真菌接种显著提高枳的叶片蔗糖和根系葡萄糖含量,但降低叶片葡萄糖和根系蔗糖含量.由于根系“菌根碳库”的存在,丛枝菌根真菌接种导致根系维持较高的葡萄糖和较低的蔗糖含量,从而有利于宿主根系的生长和发育,建立更优的根系形态.     

模拟氮沉降和不同外生菌根真菌侵染对樟子松幼苗生长的影响

盆栽条件下,采用单接种Suillus bovines(以下简称SB)和混合接种(Suillus luteus、Suillus grevillea、Tricholoma fulvum、Boletinus grisellus、Suillus bovinus、Leucocortinarius bulbiger、Rhizopogon luteolus、Pisolithus tinctorius 8个菌种的等量混合菌剂接种,以下简称HJ)方法对樟子松(Pinus sylvestris var.mongolica)2个月幼苗进行接种处理,幼苗生长6个月形成菌根后对樟子松幼苗进行模拟氮沉降实验,5个月后通过测定幼苗生长指标、根系形态结构和菌根侵染率,旨在探讨模拟氮沉降对樟子松不同接种处理幼苗生长的影响。结果表明:①随着氮浓度的增加,单接种乳牛肝(SB)和混合接种(HJ)菌根侵染率均呈下降趋势,且氮沉降对SB处理的菌根侵染率影响更显著。②接种显著促进幼苗地上和地下生物量积累,且混合接菌效果更好;同一接菌处理中,氮浓度增加对地上生物量的积累有抑制作用;接种和氮浓度对地径和地上生物量有显著交互作用,但对苗高和地下生物量无交互作用。③HJ处理中不施氮(CKN)和1倍氮浓度(CN)较不接菌(CK)和SB处理显著促进幼苗根系的平均直径、总根长和总表面积;氮浓度增加显著促进CK和SB处理的幼苗根系平均直径、总根长和总表面积,但是对HJ处理的根系各形态结构指标均产生抑制作用。接种和氮浓度以及两者的交互作用均极显著影响幼苗根系形态结构。     

磷水平对接种丛枝菌根真菌甜玉米苗期生长的影响

研究了不同外源磷水平条件下,接种丛枝菌根真菌根内球囊霉(Glomus intraradices)对寄主植物甜玉米菌根侵染率、地上部和地下部鲜重、氮磷含量、精氨酸含量影响。结果表明:丛枝菌根真菌能够很好的侵染于玉米植株根系。且不同磷水平条件下,菌根侵染率差异较显著。在低磷水平下,菌根侵染率较高。孢子数量随着磷水平提高而增加。菌丝室根外菌丝鲜重在P40时最高。菌根化的甜玉米生物量及氮磷含量显著高于对照组。此外,低磷水平促使甜玉米地上部和地下部鲜重显著提高。甜玉米地上部总氮和地下部总氮含量分别在P40、P80和P20、P40时最高。地上部总磷和地下部总磷含量分别在P80和P160时最高。菌根精氨酸含量在低磷(P20)时最高。研究表明接种丛枝菌根真菌可促进甜玉米幼苗生长并与外源磷水平有关。     

水分胁迫和接种菌根真菌对青冈栎根系形态的影响

以石漠化地区造林树种青冈栎幼苗为试验材料,在盆栽条件下,分别用内生菌根真菌摩西球囊霉(Glomus mosseae,Gm)、根内球囊霉(Glomus intraradices,Gi)、外生菌根真菌彩色豆马勃(Pisolithus tinctorius,Pt)和3种菌根真菌混合菌剂进行接种,利用根系扫描仪Epson Perfection V700和根系分析软件WinRhizo,研究了正常水分、中度干旱和重度干旱条件下菌根真菌对青冈栎幼苗根系形态的影响。结果表明:在土壤干旱条件下,接种菌根真菌使青冈栎根系生物量、总根长、根表面积和根体积显著增加,使根平均直径减小;在土壤中度干旱胁迫下,Pt处理根表面积显著高于Gm和Gi处理,而根平均直径显著小于Gm和Gi;在重度干旱胁迫下,Pt处理根生物量和根体积显著小于Gm和Gi,根平均直径显著大于Gm和Gi;相关性分析表明,菌根侵染率与根生物量和总根长呈极显著正相关。本研究表明,在干旱条件下,菌根真菌可改变青冈栎幼苗根系形态,促进碳水化合物向根系积累和分配。     

丛枝菌根真菌促进湿地植物对污染水体中镉的吸收

丛枝菌根真菌(AMF)具有促进植物生长、增强植物耐重金属毒害及修复重金属污染生境的作用.本试验于模拟湿地系统中设0、5、10和20 mg·L^-1镉浓度,对芦苇和狼尾草分别进行接种和不接种摩西斗管囊霉(Fm)、根内根孢囊霉(Ri)处理.结果表明: 镉污染降低了AMF侵染;接种AMF提高了芦苇和狼尾草的株高、干质量、叶绿素含量、地上部与根内的氮和镉含量,增强了根系对镉的富集能力,降低了镉转移系数.在5 mg·L^-1镉处理下,接种Fm的芦苇处理的各项指标均高于其他处理,其AMF侵染率为60.6%,每毫米根长的侵入点和泡囊数分别为2.3和3.7;与不接种对照相比,接种Fm的芦苇地上部与根系干质量分别提高69.1%和75.0%,地上部与根系氮含量分别提高38.7%和27.8%,叶绿素含量和株高分别增加3.8%和11.1%.湿地系统镉浓度与植株地上部和根内的镉含量呈显著正相关.在20 mg·L^-1镉处理下,接种Fm的芦苇地上部和根内镉含量达到最大值182.4和663.3 mg·kg^-1,镉转移系数最低,为0.27,而富集系数最高,为0.55.Fm+芦苇是本试验条件下吸收富集污染水体中镉的最佳组合.     

土施糖类对丛枝菌根真菌侵染率和产孢的影响

丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)不能进行光合作用,需要宿主植物提供碳水化合物供其完成整个生命周期,添加外源物质调控AMF和宿主植物的关系被认为是一种可行的措施。通过盆栽实验种植番茄,探索土施不同糖类对摩西球囊霉Glomus mosseae的侵染率、产孢能力和功能(宿主植物生长和养分)的影响。结果表明,添加葡萄糖和蔗糖可提高接种了摩西球囊霉的番茄的地上部生物量以及磷、钾吸收量,但对地上部氮吸收量影响不显著;添加麦芽糖和淀粉对地上部生物量及氮磷钾养分吸收量的影响均不显著。添加糖类处理,土壤碱解氮均有下降趋势;土壤速效磷、速效钾随着地上部磷和钾吸收量增加有下降趋势。糖类添加对土壤有机质没有影响。添加不同糖类均提高了AMF的侵染率,其中添加蔗糖处理的侵染率较单独施用摩西球囊霉菌处理增加了114%。单独施用摩西球囊霉菌剂处理土壤孢子数为10个/g,添加葡萄糖和淀粉处理的孢子数均为8个/g,添加蔗糖和麦芽糖处理的孢子数均为11个/g,添加糖类均对AMF产孢无显著影响。     

不同外源氮对丛枝菌根真菌Rhizophagus irregularis侵染棉花植株和氮磷转运的影响

探究供应外源氮对接种AM真菌的棉花植株的侵染率和氮磷转运的影响。本文以棉花为研究对象,接种丛枝菌根真菌(Rhizophagus irregularis),向根外菌丝额外供应不同外源氮,测AM真菌的侵染率、棉花植株株高、地上部和地下部鲜重、叶绿素含量、菌根精氨酸含量、地上部的氮磷含量。试验结果显示:不同外源氮条件下,AM真菌对棉花植株的生物量无显著性影响;外源氮的供应均提高了AM真菌的侵染率和棉花植株地上部的氮含量,但硫酸铵和硝酸钾更能促进AM真菌侵染宿主植物,提高宿主植物菌根精氨酸水平和地上部氮含量;除了尿素,其他氮源处理均能明显提高棉花植株地上部磷含量,其中,精氨酸最为显著。说明在AM共生系统中外源氮的供应对宿主植物生长无显著作用,但促进AM真菌侵染宿主植物,并能提高宿主植物氮磷含量。     

接种丛枝菌根真菌对青冈栎幼苗生长和光合作用的影响

利用菌根真菌摩西球囊霉和根内球囊霉,对喀斯特地区造林树种青冈栎进行接种试验,测定菌根真菌对青冈栎幼苗生长、生物量和光合作用的影响。结果表明:接种丛枝菌根真菌能显著促进青冈栎幼苗株高、地径、叶面积和幼苗生物量的增长,并且能提高幼苗成活率和改善幼苗的光合能力。摩西球囊霉和根内球囊霉处理的青冈栎幼苗生物量分别是未接种处理的2.1和1.9倍;摩西球囊霉和根内球囊霉处理下的水分利用效率分别比对照处理提高了33.6%和8.8%;摩西球囊霉对青冈栎幼苗株高、地径、生物量的促进作用好于根内球囊霉,而根内球囊霉处理的幼苗叶面积、主根长、根冠比大于摩西球囊霉处理。总体而言,接种丛枝菌根真菌特别是摩西球囊霉能促进青冈栎幼苗的生长和生物量增长,在石漠化植被恢复中具有潜在应用价值。     

Biochar and Arbuscular mycorrhizal fungi mediated enhanced drought tolerance in Okra (Abelmoschus esculentus) plant growth,root morphological traits and physiological properties

Drought is a major abiotic factor limiting plant growth and crop production. There is limited information on effect of interaction between biochar and Arbuscular mycorrhizal fungi (AMF) on okra growth, root morphological traits and soil enzyme activities under drought stress. We studied the influence of biochar and AMF on the growth of Okra (Abelmoschus esculentus) in pot experiments in a net house under drought condition. The results showed that the biochar treatment significantly increased plant growth (the plant height by 14.2%, root dry weight by 30.0%) and root morphological traits (projected area by 22.3% and root diameter by 22.7%) under drought stress. In drought stress, biochar treatment significantly enhanced the chlorophyll ‘a’ content by 32.7%, the AMF spore number by 22.8% and the microbial biomass as compared to the control. Plant growth parameters such as plant height, shoot and root dry weights significantly increased by AMF alone, by 16.6%, 21.0% and 40.0% respectively under drought condition. Other plant biometrics viz: the total root length, the root volume, the projected area and root diameter improved significantly with the application of AMF alone by 38.3%, 60.0%,16.8% and 15.9% respectively as compared with control. Compared to the control, AMF treatment alone significantly enhanced the total chlorophyll content by 36.6%, the AMF spore number by 39.0% and the microbial biomass by 29.0% under drought condition. However, the highest values of plant growth parameters (plant height, shoot dry weight, root dry weight) and root morphological traits (the total root length, root volume, projected area, root surface area) were observed in the combined treatment of biochar and AMF treatment viz: 31.9%, 34.2%, 60.0% and 68.6%, 66.6%, 45.5%, 41.8%, respectively compared to the control under drought stress. The nitrogen content, total chlorophyll content and microbial biomass increased over un-inoculated control. The soil enzymes; alkaline phosphatase, dehydrogenase and fluorescein diacetate enzyme activities significantly increased in the combined treatment by 55.8%, 68.7% and 69.5%, respectively as compared to the control under drought stress. We conclude that biochar and AMF together is potentially beneficial for cultivation of okra in drought stress conditions.     

Arbuscular mycorrhizal fungi differ in affecting the flowering of a host plant under two soil phosphorus conditions

Aims Studies have showed that arbuscular mycorrhizal fungi (AMF) can greatly promote the growth of host plants, but how AMF affect flowering phenology of host plants is not well known. Here, we conducted a pot experiment to test whether life cycle and flowering phenology traits of host plant Medicago truncatula Gaertn can be altered by AMF under low and high soil phosphorus (P) levels.Methods The experiment was conducted in a greenhouse at Zhejiang University in China (120°19′E, 30°26′N) and had a completely randomized design with two factors: AMF treatments and soil P levels. Six AMF species (Acaulospora scrobiculata, As; Gigaspora margarita, Gma; Funneliformis geosporum, Fg; Rhizophagus intraradices, Ri; Funneliformis mosseae, Fmo and Glomus tortuosum, Gt.) were used, and two soil P levels (24.0 and 5.7 mg kg^-1 Olsen-soluble P) were designed. The six AMF species were separately inoculated or in a mixture (Mix), and a non-AMF control (NAMF) was included. When plants began to flower, the number of flowers in each pot was recorded daily. During fruit ripening, the number of mature fruits was also recorded daily. After ~4 months, the biomass, biomass P content and AMF colonization of host plant were measured. Correlation between root colonization and first flowering time, or P content and first flowering time was analyzed.Important findings Under the low P level, first flowering time negatively correlated with root colonization and biomass P. Only host plants with AMF species As, Fg, Ri, or Mix were able to complete their life cycle within 112 days after sowing. And treatment with AMF species Fg, Gt, or As resulted in two periods of rapid flower production while other fungi treatments resulted in only one within 112 days after sowing. The cumulative number of flowers produced and biomass P content were highest with species Fg. Host biomass allocation significantly differed depending on the species of AMF. Under both soil P levels, the host plant tended to allocate more biomass to fruits in the Mix treatment than in the other treatments. These results indicated that the effects of AMF on host flowering phenology and biomass allocation differed depending on AMF species and soil P levels.     

干旱条件下接种AM真菌对小马鞍羊蹄甲幼苗根系的影响

为了探讨岷江干旱河谷丛枝菌根真菌(AMF)对寄主植物幼苗根系的影响,通过接种购买的AMF摩西球囊霉菌(Funneliformis mosseae)到优势乡土灌木小马鞍羊蹄甲(Bauhinia faberi var.microphylla)幼苗,在重度、中度和轻度干旱条件下培养3个月,研究不同干旱条件下AMF对幼苗根系形态特征、结构特征、功能性状的影响。方差分析结果表明:(1)3种干旱胁迫条件下,接菌均显著增加了幼苗的根总长、根表面积、根分枝数、根尖数(P0.001),在中度胁迫和轻度胁迫下,接菌显著促进根鲜重、根体积的增加(P0.001),轻度胁迫条件下接菌幼苗的根鲜重、根总长、根表面积、根体积、根尖数最高并显著高于其它处理,但接菌与未接菌的根平均直径之间没有显著差异;(2)接菌幼苗根系趋向于叉状分支结构,在重度胁迫时,叉状分支趋势更显著(P0.001);(3)接菌幼苗的根比例都显著小于未接菌的,但幼苗比根长不存在显著差异。相关分析结果表明:菌根侵染率与根鲜重、根总长、根表面积、根体积、根分枝数、根尖数呈极显著正相关(P0.001),与拓扑指数、根比例呈极显著负相关(P0.001)。研究表明,在干旱条件下,AMF虽然没有提高生长初期的根系的吸收效率,但接种AMF显著影响幼苗根系形态特征和结构特征,更利于植物适应干旱环境,并且AMF对幼苗根系的促生作用随着干旱胁迫程度减轻而提高。     

内生真菌和丛枝菌根真菌对羊草生长的影响

该研究比较了摩西球囊霉(Glmous mosseae)和幼套球囊霉(Glmous etunicatum)两种丛枝菌根真菌和内生真菌单独及混合接种对羊草(Leymus chinensis)生长的影响。结果表明, 内生真菌对2种菌根真菌的侵染均无显著影响, 内生真菌可极显著增加羊草的分蘖数、地上生物量、总生物量。内生真菌与菌根真菌之间的相互作用因菌根真菌种类而不同, 幼套球囊霉对宿主植物生长无明显影响且和内生真菌之间也无明显的相互作用; 单独接种摩西球囊霉显著增加羊草的地上、地下和总生物量, 当其与内生真菌共同存在时, 二者之间存在一定的拮抗作用。冗余分析结果表明, 在内生真菌-AM真菌-羊草共生体中, 内生真菌对宿主植物生长的影响最大, 摩西球囊霉对宿主植物生长也有一定的贡献, 幼套球囊霉对宿主植物生长无明显影响。     

西藏高原天然长芒草地丛枝菌根真菌接种效应

采用草地均匀打孔方法,就草地土壤未消毒条件下接种丛枝菌根（AM）真菌对长芒草(Stipa bungeana)的侵染效应以及对植物生长、吸磷效率、土壤微生物区系等的影响进行研究.结果表明,1)接种处理、不接种处理的菌根效应存在着明显的差异,多数接种处理根围土壤AM真菌孢子密度、菌根侵染率和侵染强度显著提高,但对丛枝丰度的影响相对较低.2)接种后AM真菌孢子密度对菌根侵染率具有极显著影响(r=0.7679**);随菌根侵染率的增加,植株总干物重和吸磷总量均呈极显著提高,r值分别为0.7556**、0.8018**.3)与植株地上部相比,接种AM真菌对提高根系干物重、根系吸磷量和含磷量的促进作用相对较大.4)多数接种处理根际土壤酸性磷酸酶、碱性磷酸酶活性均呈一定程度的提高,根际土壤细菌数量显著增加,真菌、放线菌的数量变化则不甚明显.5)各接种处理对寄主植物的综合侵染效应在总体上呈Glomus mosseae+G. intraradices+Scutellospora calospora＞G. mosseae+G. aggregatum＞Glomus sp.＞G. mosseae＞G. mosseae+ G. etunicatum+G. intraradices+S. erythropa＞G. geosporum的趋势.     

丛枝菌根真菌对砂培玉米幼苗根系特征、光合生理与镉累积的影响

【背景】丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)是一类重要的土壤微生物,能显著影响植物对镉(cadmium,Cd)的耐性与累积,但其对不同形态Cd胁迫的响应尚不清楚。【目的】探讨不同形态Cd胁迫下接种AMF对玉米(Zea mays L.)生长和Cd累积的影响。【方法】采用30 cm高的培养容器填装石英砂(0.2 mm),开展室内砂培玉米试验,研究溶解态和胶体态Cd (1 mg/kg)胁迫下,接种摩西斗管囊霉(Funneliformis mosseae)对玉米幼苗生长、根系特征、光合生理及Cd累积的影响。【结果】双因素分析表明,AMF和Cd形态均对玉米生长(株高和生物量)、根系特征、光合生理(叶绿素含量和光合速率)与Cd累积量存在显著的影响,但二者之间没有显著交互作用。与未接种处理相比,接种AMF显著降低玉米株高、生物量、叶片叶绿素含量和光合速率,抑制玉米根长、根表面积、根体积和根尖数;同时增加了玉米根系Cd含量,但减少玉米地上部Cd含量以及地上部与根系Cd累积量;与胶体态Cd处理相比,溶解态Cd显著降低玉米的根长、根表面积、平均根系直径、根尖数和地上部Cd累积量,但增加了植株叶片光合速率、根系Cd含量和累积量。相关分析发现,玉米根长、根表面积和根尖数与地上部Cd含量呈显著或极显著正相关,与根系Cd含量呈极显著负相关。【结论】溶解态Cd比胶体态Cd对砂培玉米幼苗的毒害效应严重,而且接种AMF加重溶解态和胶体态Cd对玉米幼苗的损伤,但降低了植株对Cd的累积。     

Colonization of Tanacetum vulgare by aphids is reduced by earthworms

Soil organisms affect plant growth and chemistry and have subsequent effects on aboveground herbivore performance. However, whether herbivores discriminate between plants exposed to different soil organisms when colonizing their host plants is largely unexplored. In a greenhouse study, Tanacetum vulgare L. (Asteraceae) growing in a ruderal plant community in the presence and absence of arbuscular mycorrhizal fungi (AMF) and earthworms [Aporrectodea spp. (Haplotaxida: Lumbricidae)] was colonized by aphids [Myzus persicae Sulzer (Hemiptera: Aphididae)]. The aphids preferred to colonize plants without earthworms in the soil, and the numbers of aphids remained lower on the plants with earthworms, irrespective of the presence of AMF. Although the N, C, and P concentrations of the shoots were not affected by the soil organisms, AMF increased total aboveground biomass, total N, C, and P content, and photosynthetic activity (measured as electron transport rate) in the leaves under high light intensity. These results suggest that earthworms affect chemical cues that are used by aphids to judge host quality prior to feeding. Discrimination between plants with and without exposure to earthworms by aboveground herbivores is a novel aspect of plant‐mediated interactions between below‐ and aboveground organisms.     

双色蜡蘑对黑松幼苗生长量及其根系形态的影响

为研究双色蜡蘑(Laccaria bicolor)对黑松(Pinus thunbergii)幼苗生长及其根系形态的影响,在营养杯培育条件下,用双色蜡蘑液体菌剂对黑松幼苗进行接种处理,接种第15、30、60、90、120天时取样,比较接种和未接种黑松幼苗的生物量、根系形态及根系分形维数的差异。结果表明:双色蜡蘑在黑松幼苗地上植株、地下根系的生长及其生物量的积累方面都表现出明显的促进作用。接种双色蜡蘑也显著改善了根系总长度、分支数、表面积、体积等参数和根系分形维数,并对地下根系生长的促进作用时间早于地上部分,且效应显著高于地上部分。接种双色蜡蘑第15~30天时对地上部分基本无影响,但对根系促进作用明显,而地上部分在第60天时开始表现出显著的生长效应。研究发现,双色蜡蘑能够成功定殖于黑松根部,促进黑松幼苗生长及其生物量的积累,同时显著促进根系总长度、分支数、表面积和体积增加,并使根系分形维数增大,表现出明显的促生作用,且对根系发育的显著促进作用早于地上部分。