Effect of inoculation withGlomus mosseae on nitrogen fixation by field grown soybeans

Summary This field study was undertaken to determine the effect of inoculation withGlomus mosseae on N₂ fixation and P uptake by soybean. The inoculation withGlomus mosseae was achieved using a new type of inoculant, alginate-entrapped (AE) endomycorrhizal fungus. N₂ fixation was assessed using the A value method. In P-fertilized plots, inoculation with AEGlomus mosseae increased the harvest index based on dry weight (+20%) and N content of seeds (+17%), the A value (+31%) and %N derived from fixation (+75%). Inoculation with AEGlomus mosseae decreased the coefficient of variation for the A value and for the dry weights of the different plant parts.     

Effects of ethrel on the formation and responses to VA mycorrhiza in Medicago and Triticum

Summary Ethrel, a compound which readily releases ethylene, depressed VA mycorrhiza formation inMedicago sativa andTriticum vulgare when it was either applied to the rooting medium or sprayed to the foliage. The axenic germination ofGlomus mosseae spores was found to be sensitive to ethrel suggesting that at least part of the effect of ethrel on mycorrhization could come from its effect on fungal development. The possible ecological significance of these findings is discussed.     

Effect of arbuscular mycorrhizal fungi on the acclimatization of micropropagated banana plantlets

 The effect of arbuscular mycorrhizal fungi (AMF) on micropropagated banana plantlets was evaluated during the acclimatization period. Plants were inoculated with Acaulospora scrobiculata, Glomus clarum or Glomus etunicatum. After cultivation in a greenhouse for 3 months, height, leaf area, fresh weight and dry matter of root and shoots, level of AMF colonization, nutrient level, photosynthesis and transpiration rate, water potential and stomatal conductance were measured. The number of AMF spores produced in each treatment was also determined. Plantlets inoculated with AMF had greater height, leaf area and fresh weight of shoots and roots, as well as higher rates of photosynthesis and transpiration than controls. Plants inoculated with Glomus were superior in most of the evaluated parameters. Accepted: 24 May 1999     

山珊瑚内生菌根的研究

山珊瑚内生菌根真菌在人工培养基上分离培养不能生长。侵染菌丝由山珊瑚侧根表皮侵入,在皮层中部形成侵染通道。进入皮层细胞后形成丛枝吸器。被侵染的寄主细胞仍是生活细胞,但细胞质变稀,蛋白质、RNA含量很少。近中柱的6至8层皮层细胞壁增厚并木质化。丛枝吸器含有丰富的红淀粉,少量的中性脂肪、碱性蛋白质和D NA。菌丝丛枝干幼龄期电子致密,周围有界面物质包围,在衰老时泡囊化,界面物质亦瓦解。吸器由五边形结构组成。寄主细胞在被侵染前含淀粉质体、线粒体、高尔基体、内质网和核糖体,在被侵染后,淀粉质体消失,其它细胞器数量明显减少,而主要是微丝和小液泡及多泡体。文章讨论了山珊瑚菌根与天麻和泡囊-丛枝菌根的异同。     

Influence of soil pH on the soybean-endomycorrhiza symbiosis

Summary Soybean (Glycine max {L.} Merr.) cultivars were inoculated withGigaspora gigantea andGlomus mosseae to determine mycorrhizal: cultivar relationships as affected by soil pH. The specific cultivarfungal response was dependent on soil pH. Overall cultivar responses in unlimed soil (pH 5.1) were greater forG. gigantea thanG. mosseae. The Bossier —G. gigantea combination was particularly responsive in unlimed soil and showed an increase of 10% in shoot length, 35% in shoot dry weight. 75% in root dry weight, and 397% in nodule dry weight over uninoculated controls. Little cultivar response was observed withG. mosseae inoculation in unlimed soil. In limed soil (pH 6.2), the larger responses were obtained withG. mosseae inoculated plants, although inoculation with eitherG. mosseae orG. gigantea appeared effective. In general, nodulation was greater on mycorrhizal roots than on control roots.     

两类专性寄生真菌侵染植物的组织学染色技术初步研究

研究了锈菌和内生菌根真菌侵染寄主组织的品红染色技术,描述了海棠和酢浆草与真菌互作的组织学过程,阐明了山田胶锈菌对海棠的侵染过程与病变性组织变化,描述了菌根菌从根冠侵入和菌丝体网络形成过程。实验表明,该法是研究真菌侵染组织学的良好方法。     

Ability of symbiotic and non-symbiotic rhizospheric microflora of maize (Zea mays) to weather micas and to promote plant growth and plant nutrition

Summary Maize was grown under axenic conditions in laboratory devices, in a K⁺-deficient medium, where biotite was the K⁺ source. In different treatments plants were inoculated by symbiotic (Glomus mosseae) and/or non symbiotic microflora. In those treatments inoculated byGlomus mosseae, the percentage of roots infection after 7 weeks plant growth was 65%. Rhizospheric bacterial population was approximately 10⁸/g (dry weight). Endomycorrhizae stimulated growth and K uptake. Non-symbiotic microflora increased also plant growth but promoted much more biotite weathering and K uptake. Endomycorrhizae and more particularly non-symbiotic microflora increased also Ca and Mg absorption by plants. Possible mechanisms involved and implications in plant growth and pedogenesis are discussed.     

The Glycine-Glomus-Rhizobium symbiosis

Soybean [ Glycine max , (L.) Merr, cv. Lancer] plants were grown in a sterile rooting medium watered daily with a nutrient solution containing 4, 20, 100, or 500 μM, P. Plants were inoculated with Rhizobium japonicum , strain 61A118 and grown in the presence or absence of the endomycorrhizal fungus Glomus fasciculatus , Gerdemann et Trappe. Plants grown at the highest P regime had six times higher shoot dry weight than those grown in the lowest P regime. Nodulation did not occur at 4 μM P. Nodule dry weight increased 200-fold from the 20 to the 500 μM P treatment. Percentage P in shoots and nodules differed significantly among all treatment levels. Acetylene reduction by nitrogenase increased logarithmically with increasing amounts of P. Hydrogen evolution was not detectable at the 20 μM P level. The relative efficiency of nitrogen fixation increased with increasing P stress. Infection by Glomus fasciculatus , at the 500 μM P level was negligible and did not affect the parameters measured. At all other treatment levels the mycorrhizal plants had significantly higher rates of N₂ fixation, plant and nodule mass and P content.     

Interaction of vesicular arbuscular mycorrhiza with root knot nematodes in tomato

Summary The interaction between the VA mycorrhizal fungus,Glomus fasciculatus and the root-knot nematodes,Meloidogyne incognita andM. javanica, and their effects on the growth and phosphorus nutrition of tomato was studied in a red sandy loam soil of pH 6.0. Inoculation of tomato roots with root-knot nematodes enhanced infection and spore production byG. fasciculatus. Inoculation of tomato plants withG. fasciculatus significantly reduced the number and size of the root-knot galls produced byM. incognita andM. javanica. Inoculation withG. fasciculatus although improved plant growth and its total phosphorus content compared to the uninoculated plants, the difference were not statistically significant.     

广西人工栽培铁皮石斛内生菌根的研究

通过光学生物显微镜及Qwin图像分析系统,对人工繁育栽培的铁皮石斛各生长期植株的内生菌根进行了观察分析。结果表明:铁皮石斛具有典型的内生菌根;铁皮石斛根内共生菌不是其原有的,而是通过栽培基质传与铁皮石斛的根而共生。被真菌侵染的区域大,其植株生长茂盛,真菌对铁皮石斛的生长发育可能有促进的作用。