Using arbuscular mycorrhiza to reduce the stressful effects of soil compaction on corn (Zea mays L.) growth

Soil compaction is of great importance in agriculture, because its high levels may adversely affect plant growth and the environment. Since mechanical methods are not very efficient and economical, using biological methods to alleviate the stress of soil compaction on plant growth may be beneficial. The objectives of this study were to: (1) evaluate the effects of soil compaction on corn (Zea mays L.) growth, and (2) test the hypothesis that applying arbuscular mycorrhiza (AM) with different origins can partially or completely overcome the stressful effects of soil compaction on corn growth under unsterilized and sterilized conditions. Corn was planted in unsterilized and sterilized compacted soils, while treated with three species of AM including, Iranian Glomus mosseae, Iranian Glomus etunicatum, and Canadian Glomus mosseae, received from GINCO (Glomales in vitro Collection), Canada. Plant growth variables and soil resistance parameters were determined. AM significantly increased root fresh (maximum of 94% increase) and dry (maximum of 100% increase) weights in the compacted soil. AM with different origins may improve corn growth in compacted soils, though its effectiveness is related to the level of compaction and also to the interaction with other soil microorganisms.     

Utilization of Sparingly Soluble Phosphate by Red Clover in Association with Glomus mosseae and Bacillus megaterium

A pot experiment was conducted to investigate the mobilization of sparingly soluble inorganic and organic sources of phosphorus (P) by red clover (Trifolium pratense L.) whose roots were colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae and in association with the phosphate-solubilizing (PS) bacterium Bacillus megaterium ACCC10010. Phosphate-solubilizing bacteria and rock phosphate had a synergistic effect on the colonization of plant roots by the AM fungus. There was a positive interaction between the PS bacterium and the AM fungus in mobilization of rock phosphate, leading to improved plant P nutrition. In dual inoculation with the AM fungus and the PS bacterium, the main contribution to plant P nutrition was made by the AM fungus. Application of P to the low P soil increased phosphatase activity in the rhizosphere. Alkaline phosphatase activity was significantly promoted by inoculation with either the PS bacterium or the AM fungus.     

接种丛枝菌根真菌对小麦根内氮转运蛋白基因表达的影响

通过盆栽试验,研究了在低氮(不施氮)和高氮(施氮0.2 g·kg~(-1))水平下接种不同种类丛枝菌根(AM)真菌[Funneliformis mosseae(BGC-NM03D)、Claroideoglomus etunicatum(BGC-NM01B)和Rhizophagus intraradices(BJ09)]对小麦生长、氮吸收及根内4个硝态氮转运蛋白(NRT)基因、1个辅助蛋白(NAR)基因和2个铵态氮转运蛋白(AMT)基因表达的影响。结果表明,3种AM真菌均能够侵染小麦根系,以R.intraradices菌根的侵染率最高;接种R.intraradices或C.etunicatum能够显著提高小麦的生物量或地上部氮吸收量;无论是高氮还是低氮处理,接种AM真菌后均显著下调了小麦根内NRT、NAR和AMT基因的表达水平,且不同AM真菌调控小麦根内氮转运蛋白基因表达的能力具有明显差异。     

AM真菌生长发育影响因素及其对植物作用的研究

由真菌与植物根系共生形成的AM菌根在自然界中分布广泛，其牛长发育受温度、土壤湿度等条件的影响；AM菌根可以促进宿主植物的生长已经在许多植物上得到证实，此外。此类菌根对提高植物的耐盐性、抗旱性及抗重金属毒性方面都有显著的作用。     

Infection of valuable broadleaf hardwood trees by Glomus mosseae: growth and mineral nutrition

In the past century, the excessive exploitation of the environment by human beings has resulted in the depletion of valuable broadleaf hardwood trees in Italian forests, creating a need for re-forestation. The aim of this research was to verify whether a vescicular-arbuscular mycorrhizal (VAM) fungus is able to colonise the root of valuable hardwood trees and to evaluate the impact of the VAM fungus on growth and macroelement nutrition of its plant hosts.Four species of valuable broadleaf hardwood trees, Prunus avium L., Fraxinus excelsior L., Acer pseudoplatanus L., and Juglans nigra L., were inoculated with Glomus mosseae, a VAM fungus, and cultivated in a greenhouse. Infection after inoculation and root colonization by the fungus, tree growth, and macro-element nutrition were evaluated two-years after inoculation. G. mosseae formed mycorrhizae on all plants. However, different morphological aspects - predominantly the formation of Arum type arbuscles in P. avium and F. excelsior - were observed. A general improvement of macro-element nutrition from species to species characterised an enhanced growth of mycorrhizal plants. Therefore, it is plausible that the association of VAMs with these broadleaf trees, could overcome the difficulties encountered in the transplanting and the slow growth typical of these tree species.Although numerous articles have reported the beneficial effects of ectomycorrhizal fungi on trees, there is a sparse literature on the association of VAM with tree species. Therefore, this study contributes to the understanding of the role of the symbiosis between valuable broadleaf trees and VAM fungi in macroelement nutrition.     

Inter‐specific variability in organic nitrogen uptake of three temperate grassland species

We tested the inter‐specific variability in the ability of three dominant grasses of temperate grasslands to take up organic nitrogen (N) in the form of amino acids in soils of differing fertility. Amino acid uptake was determined by injecting dual labeled glycine‐2‐¹³C‐¹⁵N into the soil, and then measuring the enrichment of both ¹³C and ¹⁵N in plant tissue after 50 hours. We found enrichment of both ¹³C and ¹⁵N in root and shoot material of all species in both soils, providing first evidence for direct uptake of glycine. We show that there was considerable inter‐specific variability in amino acid uptake in the low fertility soil. Here, direct uptake of amino acid was greater in the grass Agrostis capillaris, which typically dominates low fertility grassland, than Lolium perenne, which inhabits more fertile sites. Direct uptake of amino acid for Holcus lanatus. was intermediate between the above two species. Unlike in the low fertility soil, there was no difference in uptake of either ¹³C or ¹⁵N by grasses in the high fertility soil, where uptake of mineral N is thought to be the major mechanism of N uptake of these grasses. Overall, our findings may contribute to our understanding of differences in competitive interactions between grasses in soils of different fertility status.     

梅花根际土壤栽培三叶草的丛枝菌根侵染研究

从北京、武汉、南京、重庆、昆明五个梅园和野梅主要分布区的云南嵩明、四川木里、贵州茂兰自然保护区,以及北京林业大学的梅圃中分别于春、夏、秋、冬四季,采集梅花根际土壤300份。以梅花根际土壤和蛭石体积为1∶1混合作为栽培基质,种植三叶草,培养4个月后,应用染色镜检法测定丛枝菌根真菌(AMF)侵染三叶草根系的状况。结果表明:所有梅花根际土壤栽培三叶草都有丛枝菌根侵染;野生梅花根际土壤栽培三叶草的丛枝菌根侵染率高于人工梅园;四季的梅花根际土壤栽培三叶草丛枝菌根侵染在季节间无明显差异。     

桔园生草对丛枝菌根形成及果实品质的影响

试验以枳砧温州蜜柑成年树为试材。试验设土壤水分胁迫下百喜草生草区和清耕区2个处理,以清耕加轻度灌水为对照,4次重复。结果表明利用高菌根侵染率的百喜草在柑桔园进行生草管理,在土壤水分胁迫下,显著地提高了柑桔根系丛枝菌根侵染率及土壤丛枝菌根菌孢子数。菌根侵染率的提高改善了柑桔果实的品质,特别是促进了柑桔果皮的着色。生草管理还蓄养了土壤水分。