Arbuscular Mycorrhizal Infection Research Articles

Effects of P Fertilization on Growth, Yield and Arbuscular Mycorrhizal Infection Rate of Groundnut Grown in Kunigami Marge (Acrisols)

沖縄県には難溶性の鉄型リンを多く含む国頭マージ（acrisols）が広く分布する．低リン耐性の強いことが知られているラッカセイの国頭マージにおける適正リン酸施肥量を把握するために，水溶性リンが主体の過リン酸石灰を用いて無施肥（P0），標準施肥（P1），半量施肥（P0.5），倍量施肥（P2）の4処理区を設けてプランター栽培試験を4年間実施した．試験開始年はP0からP2で生育量と子実重に有意な差は見られなかった．試験を継続することでP0とP0.5は生育量と子実重が有意に減少したが，P2ではP1と同程度であった．子実リン吸収量は土壌の各種リン含有率と高い対数回帰の関係にあり，子実重とも高い対数回帰の関係にあったことから，国頭マージでのラッカセイ栽培では，P1の9 g/m2程度のリン酸施肥を行う必要があると思われる．また，ラッカセイの菌根菌感染率はP0.5からP2までリン酸施肥量を増やしてリン肥沃度が高くなっても低下せず，リン肥沃度が高い場合でも菌根菌の作用が重要である可能性が示された．

Drought Changes the Trade-Off Strategy of Root and Arbuscular Mycorrhizal Fungi Growth in a Subtropical Chinese Fir Plantation

As a consequence of changing global rainfall patterns, frequent extreme droughts will significantly affect plant growth and ecosystem functions. Fine roots and arbuscular mycorrhizal fungi (AMF) both facilitate Chinese fir nutrient uptake. However, how the growth of fine roots and AMF is regulated for the Chinese fir under drought conditions is unclear. This study used a precipitation reduction treatment (−50% throughfall) to study the seasonal effects of drought on a subtropical Chinese fir plantation. The effects measured included the fine root production, root diameter, specific root length, specific surface area, root tissue density, mycorrhizal hyphal density, spore number, mycorrhizal infection rate and total glomalin. Drought had no significant effect on Chinese fir fine root production but decreased the diameter and tissue density of primary and secondary roots while increasing the specific surface area of secondary roots. Additionally, drought significantly decreased the arbuscular mycorrhizal infection rate and significantly increased hyphal density. The results showed that drought caused the decrease in root diameter, which decreased the surface area available for AMF infection and led to the increase in mycorrhizal hyphal density. Redundancy analyses showed that soil-dissolved organic carbon and nitrogen were the key factors affecting AMF. Our results show that drought could enhance the cooperative strategy of nutrient and moisture absorption by roots and mycorrhizae of the Chinese fir, improving the resistance of Chinese fir growth to drought.

Influences of mycorrhizal inoculum on Cd and Pb uptake by wheat plant

Influences of mycorrhizal inoculum on Cd and Pb uptake by wheat plant

Development and Activity of Vesicular–Arbuscular Mycorrhizal Infection of Trifolium pratense L. in the Course of a Meadow Phytocoenosis Succession

This paper describes symbiotic relationships at various succession stages of a meadow phytocoenosis using the example of vesicular–arbuscular mycorrhiza of Trifolium pratense L. It is established that the functional potential of symbiotic relationships changes in the course of the succession, and it is fully realized in undisturbed climax communities. It is shown that discriminant analysis of biometric parameters of a single leguminous plant performed taking into account its symbiotic potential can be used for biological diagnostics of the phytocoenosis state (i.e., succession stage).

Investigating arbuscular mycorrhizal fungal infection in medicinal plant roots in different localities of tehsil Shabqadar, district Charsadda, and Khyber Pakhtunkhwa Province, Pakistan

Investigating arbuscular mycorrhizal fungal infection in medicinal plant roots in different localities of tehsil Shabqadar, district Charsadda, and Khyber Pakhtunkhwa Province, Pakistan

桉树种植对林地土壤丛枝菌根真菌群落结构及多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 桉树种植对林地土壤丛枝菌根真菌群落结构及多样性的影响 DOI: 10.5846/stxb201804140855 作者: 作者单位: 华南农业大学,华南农业大学,华南农业大学,华南农业大学,华南农业大学,华南农业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业局科技项目（AS-2017-01）；广东省林业厅项目（粤财农[2017]83号） Diversity and structure of the soil arbuscular mycorrhizal fungal community are altered by Eucalyptus plantations Author: Affiliation: South China agricultural University,South China agricultural University,South China agricultural University,South China agricultural University,South China agricultural University,South China Agruiculture University Fund Project: the Project of the Department of Forest of Guangdong Province（YUE CAI NONG [2017] No.83) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:桉树（Eucalyptus spp.）种植所产生的生态争议已受到广泛关注。丛枝菌根真菌（Arbuscular Mycorrhizal Fungi，AM真菌）是土壤微生物的重要组成部分，与根系共生后可促进植物的养分运输、提高植物逆境生存能力等。然而，桉树种植对土壤AM真菌群落结构和功能的影响尚不清楚。研究比较了次生林改种桉树后不同年限（2年/5年/10年）的土壤理化性质、AM真菌种类、群落组成及多样性的变化。结果表明，桉树种植显著改变了土壤理化性质，具体表现为2年生和10年生桉树林中土壤pH和有机碳显著降低（P < 0.05）；AM真菌的孢子密度在桉树林土壤中显著低于次生林土壤（其中在5年生土壤中最低）；AM真菌的种丰度随种植年份的增加逐渐下降，在10年生桉树林土壤中有所恢复；5年生桉树的菌根侵染率最高，10年生桉树侵染率最低。AM真菌群落组成和结构发生显著变化，优势种Funneliforms geosporus的丰度在2年生和10年生林地中显著降低；而Septoglomus deserticola的丰度在2年生和10年生林地中显著增加。另外，冗余分析（Redundancy analysis，RDA）结果表明，土壤AM真菌群落结构主要受土壤pH值（解释率：89.88%）变化的影响。研究揭示了次生林改种桉树林后土壤AM真菌的群落变化特征，为桉树林的栽培管理和环境修复提供了数据支撑。 Abstract:Eucalyptus plantations are controversial because of its complexed impacts on environments. Arbuscular mycorrhizal (AM) fungi in soil provide important ecological functions such as enhancing soil nutrient transportation and plant stress tolerance via symbiosis. Until recently, the influence of massive Eucalyptus planting on soil microbial communities, especially the AM fungi is yet to be investigated. Herein, we investigated into these effects by comparing the diversity and taxonomic composition of AM fungal community in soil between the secondary forest and Eucalyptus forests which involved two-, five-, and ten-year's plantations. Our results provided evidence that the practices of Eucalyptus plantations significantly changed soil properties (P < 0.05), e.g., the soil pH and soil organic carbon significantly decreased in the two- and ten-year's soil samples relative to the secondary forest. Importantly, spore density of AM fungi in soil declined by the Eucalyptus plantations, with the lowest level being observed in the five-year plantation. Species richness of AM fungi inclined to decrease within five years of Eucalyptus plantation, but recovered to a contain extent after ten years. In contrast, AM infection rate on the roots of Eucalyptus reached to the highest and lowest level in the five-year and ten-year plantation, respectively. Further, the composition and structure of AM fungi shifted significantly by Eucalyptus plantations. Noticeably, the dominant species Funneliformis geosporus and Septoglomus deserticola significantly decreased and increased in the two- and ten-year Eucalyptus plantations, respectively. Lastly, our redundancy analysis indicated that soil pH largely promoted the variation of the AM fungal community (explanation rate: 89.88%). Collectively, our study revealed the shifts of AM fungi in the soil of the secondary forest after the practices of Eucalyptus plantations, which is necessary to shed light onto the strategies of environment restoration in Eucalyptus plantations. 参考文献 相似文献 引证文献

Assessment of arbuscular mycorrhizal association in some fruit and spice plants of Rangamati hill district

Rhizosphere soils of some fruit and spice plants from the Hill Agricultural Research Station, Bangladesh Agricultural Research Institute, Raikhali, Rangamati were collected during 2011-12 and 2012-13 for counting Arbuscular Mycorrhizal (AM) spore population, determining colonization (%) in their roots and studying AM structure. Assessment of spore population was done by following the Wet Sieving and Decanting Method. The percentage of AM infection was estimated by root slide technique. The spore number of 100g rhizosphere soil was recorded ranging from 120 in rhizosphere soil of Malta plant to a maximum of 410 in Atafal and Sofeda plants during 2011-12 and from 75 in rhizosphere soil of Phalsa plant to a maximum of 327 in Amlaki plant during 2012-13. Different fruit and spice plants showed different percentages of root colonization by AM fungi. Among the fruit and spice plants, the highest colonization (40%) was found in Jabotica, Phalsa and Sofeda plant, and the lowest colonization (6.6%) was found in Rambutan plant during 2011-12, but in 2012-13 the highest (61.3%) was result was observed in Bilatigab plant and the lowest (18.7%) was in Misti lebu, Malta and Tetul plant. The AM fungal structure in the root system of the selected fruit and spice plants varied in irrespective of fruit and spice species. Some plants had vesicles. Hyphae were present in most of the plants. Some plant species recorded Arbuscules. Both oval and spherical shape vesicles were found in this study.Bangladesh J. Agril. Res. 42(2): 221-232, June 2017

Mycorrhizal association and influence on growth of Asian pigeonwings (Clitoria ternatea L.)

Clitoria ternatea L. is an excellent herbal medicinal plant. Arbusular Mycorrhizal fungal (AMF) colonization and biomass of three different tested conditions of Clitoria ternatea plant was investigated. Inoculums of indigenous AMF and Trichoderma harzianum was tested greenhouse experiment and compared with natural condition after 60th days of treatment. Percentage of Arbuscular mycorrhizal (AM) infection, number of resting spores and AM fungi species varies in different land. Among three different conditions, natural conditions showed maximum root colonization (75.89%) than treated one but minimum spore density (358.8/100gsoil). Highest spore density (481.6/100g soil) was found in T. harzianum treated condition followed by indigenous AMF treatment Acaulospora Glomus and Sclerocystis these three genera were found frequently. AMF inoculums and T.harzianum treatments conditions were observed promising biomass data of 60th days after treatment (DAT).When AMF are more colonized to plants then enhanced the biomass productivity.

Responses of wheat plants to interactions of 24-epibrassinolide and Glomus mosseae in saline condition.

This study was designed to investigate the possible effects of 24-Epibrassinolide (BR), arbuscular mycorrhizal (AM) fungus, Glomus mosseae, singularly and collectively under salt stress in wheat (Triticum aestivum L.) plants. After foliar spraying of mycorrhizal and non-mycorrhizal plants by 5µM epibrassinolide (24-Epi), they were treated with 0 and 150mM NaCl for 2weeks and then harvested. The results showed interactions of G. mosseae and 24-Epi could alleviate the adverse effects of salinity by improving relative water content (RWC) of leaves (62%), relative growth rate (40.74%), shoot fresh weights (39.83%) and shoot phosphorous content (63.93%), stimulating leaf enzymatic antioxidant activities including catalase (2.24 fold) and ascorbate peroxidase (2.18 fold) as well as malondialdehyde (36.17%) and H2O2 concentrations (49.74%) as compared to those of NaCl treatments. Moreover, mycorrhizal dependency of root dry weight (2%) and phosphorus concentration (0.4%) increased with AM infection and 24-Epi application under saline condition. Leaf RWC, also, negatively correlated with membrane electrolyte leakage. Furthermore, the greatest mitigating effects were observed in mycorrhizal plants subjected to NaCl and 24-Epi. This study indicated that 24-Epi application and AM fungi may synergistically mitigate harmful impacts of salinity in wheat plants.

Changes in the anatomy, morphology and mycorrhizal infection of fine root systems ofCryptomeria japonicain relation to stand ageing

Biomass allocation to fine roots often increases under soil nutrient deficiency, but the fine root biomass does not often increase in old stands, even under nutrient limitation. Therefore, in old stands, the morphology, anatomy, branching architecture and mycorrhization of fine roots may compensate efficiently for nutrient acquisition by the low fine root biomass. In this study, changes in the morphology, anatomy and arbuscular mycorrhizal infection at each branching position of fine root clusters were evaluated in relation to stand age. A chronosequence (6–90 years of age) of stands in a Cryptomeria japonica D. Don plantation was used for these analyses. The fine root size parameters, such as length, weight and tip numbers of fine root clusters, increased with stand age. The specific root tip length (SRTL) decreased with increasing stand age, suggesting that the allocation to root active portions decreased with stand age. From the anatomical observation, the ephemeral root tips increased with stand age, suggesting that root tip turnover within a root cluster was high in old stands. The proportions of proto-xylem groups among branching positions indicated that the life cycles in branching hierarchy should be clearer in old stands than that in younger stands. The increasing in the mycorrhizal infection of root tips in old stands should enhance the root tip absorptive functions. The SRTL was correlated with the wood/needle ratio, suggesting that carbon limitation as the stand ages may result in decline of carbon allocation to maintain active root tips. However, increasing of the ephemeral tips and mycorrhizal infection rates may compensate the declines of tip allocation in old stands.

Effect of conventional and organic orchard floor management practices on arbuscular mycorrhizal fungi in a ‘Cripp’s Pink’/M7 apple orchard soil

Arbuscular mycorrhizal (AM) fungi are key components of agricultural soil–plant systems, which may be affected by agricultural practices. In organically managed (ORG) orchards, nutrients are supplied in the form of compost, and weeds are suppressed with mulches, whereas synthetic fertilizers and herbicides are used for these respective purposes in conventional (CON) orchards. The effects of ORG and CON orchard floor management practices on native AM fungi in apple orchards were investigated in a randomized field trial. AM root colonization, spore abundance, infectivity potentials and soil glomalin contents were determined in the 0–30cm soil depth interval, in tree rows, over consecutive seasons. Root colonization was higher in the ORG than the CON treatments, but intermediate where straw mulch was substituted for green work-row covers. Glomalin levels were not affected by the treatments. Root colonization by AM fungi increased with increasing soil pH, P, C, K, Zn, and Mn concentrations, but were suppressed by Cu. Colonization correlated positively with leaf P, Ca and Mg, and with stem circumference, but negatively with leaf N and yield. ORG orchard floor management practices therefore, promoted functional AM associations more effectively than CON practices.

Inoculation with arbuscular mycorrhizae does not improve 137Cs uptake in crops grown in the Chernobyl region

Methods for cleaning up radioactive contaminated soils are urgently needed. In this study we investigated whether the use of arbuscular mycorrhizal (AM) fungi can improve 137Cs uptake by crops. Barley, cucumber, perennial ryegrass, and sunflower were inoculated with AM fungi and grown in low-level radionuclide contaminated soils in a field experiment 70 km southwest of Chernobyl, Ukraine, during two successive years (2009–2010). Roots of barley, cucumber and sunflower plants were slightly or moderately infected with AM fungus and root infection frequency was negatively or non-correlated with 137Cs uptake by plants. Roots of ryegrass were moderately infected with AM fungus and infection frequency was moderately correlated with 137Cs uptake by ryegrass. The application of AM fungi to soil in situ did not enhance radionuclide plant uptake or biomass. The responsiveness of host plants and AM fungus combination to 137Cs uptake varied depending on the soil, although mycorrhization of soil in the field was conditional and did not facilitate the uptake of radiocesium. The total amount of 137Cs uptake by plants growing on inoculated soil was equal to amounts in plant cultivated on non-inoculated soil. Thus, the use of AM fungi in situ for bioremediation of soil contaminated with a low concentration of 137Cs could not be recommended.

Infection intensity, spore density and inoculum potential of arbuscular mycorrhizal fungi decrease during secondary succession in tropical Brazilian ecosystems

Abstract:Little is known about the relationship involving arbuscular mycorrhizal (AM) fungi and functional groups of plants that characterize different phases of tropical succession. We appraised the AM infection intensity of root cortex and spore density in the soil in sites over tropical successional gradients (grassland, secondary forest and mature forest) for several years in Araucaria, Atlantic and Pantanal ecosystems in Brazil. The intensity of AM infection decreased with advancing successional stages in all ecosystems and it was around 60–80% in early stages of succession, 37–56% in secondary forests and 19–29% in mature forests. Similarly, the AM spore number also decreased with advancing succession and was the highest in early stages (73–123 g−1), intermediate in secondary forests (32–54 g−1) and lowest in the mature forests (10–23 g−1). To verify whether such reductions influenced the potential of AM inoculum in soil, seedlings of Heliocarpus popayanensis (Malvaceae) were grown as test plants in soils obtained from five grasslands, five young secondary forests, and five mature forests in the Atlantic ecosystem. The soil inocula from the grasslands and secondary forests were 7.6 and 5.7 times more effective in stimulating seedling growth than inocula from the mature forests, respectively. Our results show that plant species in grasslands and young secondary forests stimulate the multiplication of AM fungi, leading to a higher potential of the AM inoculum. In later-successional stages, plant investment in AM fungi decreases and the potential of the AM inoculum is also reduced.

Arbuscular Mycorrhizal Fungal Infectivity in Two Soils as Affected by Atmospheric Phenanthrene Pollution

Arbuscular mycorrhizal fungi (AMF) hold a crucial role in ecosystems because they are involved in nutrient cycling between soil and plants. This work aimed at evaluating the impacts that atmospheric pollution by polycyclic aromatic hydrocarbons may have on infectivity of indigenous AMF in soils. Two agricultural soils (Maconcourt, La Bouzule) were exposed for 2 weeks to ambient air (control, C) or to atmospheric phenanthrene (PHE) deposition (180 μg m−3 air). After exposure, soils were divided into a top (0–1 cm) and a bottom (1–15 cm) layer fraction. AMF infectivities of soils were determined after 2 weeks of atmospheric exposition using leek (Allium porum) as bioassay plant. Atmospheric PHE was mainly recovered in the top layer of soil (500–1,350 μg kg−1) of both soils and did not readily diffuse into the depth. Atmospheric contamination led to decreases in AMF infectivities of the top layer in both soils and affected the growth of leeks. Our results not only report evidence that infectivity of indigenous AMF is sensitive to PHE in soils but also emphasize that AMF are primary affected by the soil layer regardless to the pollution level.

Early arbuscular mycorrhiza colonization of wheat, barley and oats in Andosols of southern Chile

In cereals cultivated in Southern Chilean Andosols, arbuscular mycorrhizal (AM) fungi may play a main role for phosphorus (P) uptake. Because P acquisition at early growth stages is crucial for cereals, we investigated the development of indigenous AM during the first 45 days after planting of two wheat, barley and oats varieties in two typical Andosols of the region, under plastic house. Minimum temperatures were between - 5oC and + 5oC at night and maximum between 18oC and 30oC dur- ing day. The results showed that root biomass of all species increased in both soils until 30 days and remained constant thereafter until 45 days. The intensity of AM infection (root area and root biomass infected) was low at 15 days, increased slightly from 15 to 30 days and increased sharply and significantly from 30 to 45 days. Plant species and varieties differed in root biomass formation but not in frequency and intensity of infection with AM structures. Thus, those cereals species and varieties with more root production had higher total mycorrhizal root biomass, and those may potentially benefit more from AM. It is also concluded that during early growth stages cereals invest first into root development and then into AM fungal biomass.

English

&nbsp; Mycorrhizal colonization of different agroforestry tree species in two social forestry nurseries was investigated. Percentage of Arbuscular mycorrhizal (AM) infection, number of resting spores and AM fungi species varies both in tree species as well as in two different nurseries. This variation is attributed to various factors such as mycorrhizal status and other management practices. In both nurseries, Glomus species dominated in all tree species followed by Sclerocystic, Gigaspora, Acaulospora, Scutellospora and Entrophospora. Interestingly, Azadirachta indica and Terminalia catappa have shown maximum and minimum infection respectively in both nurseries. Certainly, mycorrhizae could contribute substantially to achieve better results. &nbsp; Key words:&nbsp;Arbuscular mycorrhizal fungi, agroforestry tree species.

Glomus fasciculatum in defense responses to fusarial wilt of Coleus forskohlii

The activities of enzymes responsible for disease resistance in Coleus forskohlii, pre-inoculation with an arbuscular mycorrhizal fungus, Glomus fasciculatum, and/or infection with a pathogenic strain of Fusarium oxysporum, and the biological control effect of G. fasciculatum on fusarial wilt in Coleus forskohlii were investigated. The experiment was carried out with four treatments, viz. plants pre-inoculated with G. fasciculatum, plants pre-inoculated with G. fasciculatum followed by infection with F. oxysporum, plants infected with F. oxysporum, and plants without any of the two microorganisms. Mycorrhization (%) was reduced in pathogen-challenged plants. In G. fasciculatum- and F. oxysporum- treated plants, an increase in phenolic content was observed on the 20th day while the maximum increase in phenylalanine ammonia-lyase activity was observed on the 15th day after challenge inoculation with F. oxysporum compared with that of other treatments. In G. fasciculatum- and F. oxysporum-treated plants, an increase in peroxidase and polyphenol oxidase activity was observed on the 15th day after pathogen challenge compared with that of other treatments. The observation revealed that the arbuscular mycorrhizal fungus Glomus fasciculatum systemically induced resistance against wilt disease of Coleus forskohlii via production of phenolics, the defence enzymes phenylalanine ammonia-lyase and polyphenol oxidase, and pathogenesis-related proteins, and peroxidase in response to Fusarium oxysporum infection. G. fasciculatum reduced the disease severity and promoted plant growth significantly (P<0.05) in single-treated and in combination with F. oxysporum-treated plants compared with control plants. The results suggested that G. fasciculatum is a potentially effective protection agent against F. oxysporum.

Autoregulation of Nodulation Interferes with Impacts of Nitrogen Fertilization Levels on the Leaf-Associated Bacterial Community in Soybeans

The diversities leaf-associated bacteria on nonnodulated (Nod(-)), wild-type nodulated (Nod(+)), and hypernodulated (Nod(++)) soybeans were evaluated by clone library analyses of the 16S rRNA gene. To analyze the impact of nitrogen fertilization on the bacterial leaf community, soybeans were treated with standard nitrogen (SN) (15 kg N ha(-1)) or heavy nitrogen (HN) (615 kg N ha(-1)) fertilization. Under SN fertilization, the relative abundance of Alphaproteobacteria was significantly higher in Nod(-) and Nod(++) soybeans (82% to 96%) than in Nod(+) soybeans (54%). The community structure of leaf-associated bacteria in Nod(+) soybeans was almost unaffected by the levels of nitrogen fertilization. However, differences were visible in Nod(-) and Nod(++) soybeans. HN fertilization drastically decreased the relative abundance of Alphaproteobacteria in Nod(-) and Nod(++) soybeans (46% to 76%) and, conversely, increased those of Gammaproteobacteria and Firmicutes in these mutant soybeans. In the Alphaproteobacteria, cluster analyses identified two operational taxonomic units (OTUs) (Aurantimonas sp. and Methylobacterium sp.) that were especially sensitive to nodulation phenotypes under SN fertilization and to nitrogen fertilization levels. Arbuscular mycorrhizal infection was not observed on the root tissues examined, presumably due to the rotation of paddy and upland fields. These results suggest that a subpopulation of leaf-associated bacteria in wild-type Nod(+) soybeans is controlled in similar ways through the systemic regulation of autoregulation of nodulation, which interferes with the impacts of N levels on the bacterial community of soybean leaves.

Above‐ and below‐ground plant biomass response to experimental warming in northern Alaska

AbstractQuestion: Does experimental warming, designed to simulate future warming of the Arctic, change the biomass allocation and mycorrhizal infection of tundra plants?Location: High Arctic tundra near Barrow, Alaska, USA (71°18′N 156°40′W).Methods: Above and below ground plant biomass of all species was harvested following 3–4 yr of 1‐2°C of experimental warming. Biomass allocation and arbuscular mycorrhizal infection were also examined in the two dominant species, Salix rotundifolia and Carex aquatilis.Results: Above‐ground biomass of graminoids increased in response to warming but there was no difference in total plant biomass or the ratio of above‐ground to below‐ground biomass for the community as a whole. Carex aquatilis increased above‐ground biomass and proportionally allocated more biomass above ground in response to warming. Salix rotundifolia increased the amount of above‐ and below‐ground biomass allocated per leaf in response to warming. Mycorrhizal infection rates showed no direct response to warming, but total abundance was estimated to have likely increased in response to warming owing to increased root biomass of S. rotundifolia.Conclusions: The community as a whole was resistant to short‐term warming and showed no significant changes in above‐ or below‐ground biomass despite significant increases in above‐ground biomass of graminoids. However, the patterns of biomass allocation for C. aquatilis and S. rotundifolia did change with warming. This suggests that long‐term warming may result in changes in the above‐ground to below‐ground biomass ratio of the community.

Response of Mycorrhizal Infection to Glyphosate Applications and P Fertilization in Glyphosate-Tolerant Soybean, Maize, and Cotton

ABSTRACT Glyphosate and phosphorus (P) fertilizer may alter arbuscular mycorrhizal (AM) fungal infection rates of glyphosate-tolerant cotton, maize, and soybean in low-P soil. Microbial biomass, water soluble P, Mehlich-3 P, and acid and alkaline phosphatase activities were not significantly impacted by glyphosate or P in the greenhouse. Phosphorus fertilization decreased mycorrhizal infection rates in cotton and maize and increased shoot biomass and shoot P in soybean in 2005, and decreased mycorrhizal infection in soybean and increased shoot biomass in cotton and maize and shoot P in all three crops in 2006. In pasteurized soil, glyphosate decreased percent mycorrhizal infection in maize, increased infection in cotton, and did not significantly affect infection in soybean. When soil was not pasteurized, glyphosate did not significantly alter mycorrhizal infection in any crop. The potential for glyphosate to alter AM fungal infection in glyphosate-tolerant plants may depend on whether soil microbial communities are compromised by other factors.