Department of Botany and Microbiology, Faculty of Science, Assiut University, Assiut, Egypt.
Microbiol Res. 2014 Jan 20;169(1):49-58. doi: 10.1016/j.micres.2013.07.007. Epub 2013 Aug 4.
Egyptian soils are generally characterized by slightly alkaline to alkaline pH values (7.5-8.7) which are mainly due to its dry environment. In arid and semi-arid regions, salts are less concentrated and sodium dominates in carbonate and bicarbonate forms, which enhance the formation of alkaline soils. Alkaline soils have fertility problems due to poor physical properties which adversely affect the growth and the yield of crops. Therefore, this study was devoted to investigating the synergistic interaction of Rhizobium and arbuscular mycorrhizal fungi for improving growth of faba bean grown in alkaline soil. A total of 20 rhizobial isolates and 4 species of arbuscular mycorrhizal fungi (AMF) were isolated. The rhizobial isolates were investigated for their ability to grow under alkaline stress. Out of 20 isolates 3 isolates were selected as tolerant isolates. These 3 rhizobial isolates were identified on the bases of the sequences of the gene encoding 16S rRNA and designated as Rhizobium sp. Egypt 16 (HM622137), Rhizobium sp. Egypt 27 (HM622138) and Rhizobium leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The best alkaline tolerant was R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The effect of R. leguminosarum bv. viciae STDF-Egypt 19 and mixture of AMF (Acaulospora laevis, Glomus geosporum, Glomus mosseae and Scutellospora armeniaca) both individually and in combination on nodulation, nitrogen fixation and growth of Vicia faba under alkalinity stress were assessed. A significant increase over control in number and mass of nodules, nitrogenase activity, leghaemoglobin content of nodule, mycorrhizal colonization, dry mass of root and shoot was recorded in dual inoculated plants than plants with individual inoculation. The enhancement of nitrogen fixation of faba bean could be attributed to AMF facilitating the mobilization of certain elements such as P, Fe, K and other minerals that involve in synthesis of nitrogenase and leghaemoglobin. Thus it is clear that the dual inoculation with Rhizobium and AMF biofertilizer is more effective for promoting growth of faba bean grown in alkaline soils than the individual treatment, reflecting the existence of synergistic relationships among the inoculants.
埃及土壤的 pH 值通常为弱碱性至碱性（7.5-8.7），这主要是由于其干燥的环境。在干旱和半干旱地区，盐分的浓度较低，钠以碳酸盐和碳酸氢盐的形式占主导地位，这增强了碱性土壤的形成。碱性土壤由于物理性质差而存在肥力问题，这会对作物的生长和产量产生不利影响。因此，本研究致力于研究根瘤菌和丛枝菌根真菌的协同作用，以改善在碱性土壤中生长的蚕豆的生长。共分离出 20 株根瘤菌和 4 种丛枝菌根真菌（AMF）。研究了根瘤菌在碱性胁迫下的生长能力。在 20 个分离株中，有 3 个分离株被选为耐碱分离株。这 3 个根瘤菌分离株是基于编码 16S rRNA 的基因序列进行鉴定的，并命名为 Rhizobium sp. Egypt 16（HM622137）、Rhizobium sp. Egypt 27（HM622138）和 Rhizobium leguminosarum bv. viciae STDF-Egypt 19（HM587713）。最耐碱性的是 Rhizobium leguminosarum bv. viciae STDF-Egypt 19（HM587713）。研究了 Rhizobium leguminosarum bv. viciae STDF-Egypt 19 和 AMF（Acaulospora laevis、Glomus geosporum、Glomus mosseae 和 Scutellospora armeniaca）混合物单独和组合对蚕豆在碱性胁迫下结瘤、固氮和生长的影响。与单独接种的植株相比，双接种植株的根瘤数量和质量、固氮酶活性、根瘤中豆血红蛋白含量、菌根定殖、根和茎的干重都显著增加。蚕豆固氮的增强可以归因于 AMF 促进了某些元素（如 P、Fe、K 和其他参与固氮酶和豆血红蛋白合成的矿物质）的移动。因此，很明显，与单独处理相比，用根瘤菌和 AMF 生物肥料进行双重接种更有效地促进了碱性土壤中蚕豆的生长，这反映了接种剂之间存在协同关系。
