Environmental Studies and Research Institute (ESRI), University of Sadat City, Sadat City, Menoufiya, Egypt.
Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, CSIC, 419, Granada, Spain.
Arch Microbiol. 2020 Sep;202(7):1929-1938. doi: 10.1007/s00203-020-01907-x. Epub 2020 May 25.
In a search for identification of rhizobial strains with superior N-fixation efficiency and improved plant agronomic characteristics upon inoculation, four strains, 4.21, 9.17, 11.2 and 14.1, isolated from root nodules of wild-grown Melilotus indicus have been used to inoculate field-grown common bean, pea, cowpea and fenugreek plants. Uninoculated plants and those inoculated with host-specific commercial inoculants were used as a control. The root length, shoot height, shoot dry weight and root dry weight and the grain yield of the plants were determined after harvest. The content of N, organic C and carbohydrates content of the grain were also recorded. The inoculation with the strains 4.21 and 14.1 increased the grain yield of the fenugreek compared both with the uninoculated plants and those inoculated with the commercial strain ARC-1. The grain yield of the common bean treated with the strains 9.17 and 14.1 was also higher than that of the uninoculated and the commercial strains ARC-301. In contrast, none of the strains increased the grain yield of the pea and cowpea plants compared to the commercial strains ARC-201 and ARC-169, respectively. Significant increases of some agronomical parameters were observed in some plant-bacterium couples, albeit nodulation was not observed. It is possible that the positive effects of rhizobial inoculation on the agronomical parameters of the non-nodule forming legumes could be due to plant growth promotion characteristic of the strains used for inoculation. Analysis of the phylogeny of the almost complete 16S rRNA sequence of the rhizobial inoculants revealed that the strains 4.21 and 9.17 clustered together with R. skierniewicense and R. rosettiformans, respectively, and that the strains 11.2 and 14.1 grouped with E. meliloti. All the four strains produced IAA, and showed biocontrol activity against Rhizotocnia solani, Fusarium oxysporum, Pythium ultimum, Alternaria alternata and Sclerotonia rolsfi, albeit to a different extent.
在寻找具有更高固氮效率和接种后改善植物农艺性状的根瘤菌菌株的过程中，从野生生长的草木樨根瘤中分离出的 4 株菌株 4.21、9.17、11.2 和 14.1 已被用于接种田间生长的普通菜豆、豌豆、豇豆和胡芦巴植物。未接种的植物和接种了宿主特异性商业接种剂的植物被用作对照。收获后测定植物的根长、茎高、茎干重和根干重以及谷物产量。还记录了谷物中氮、有机碳和碳水化合物的含量。与未接种的植物和接种商业菌株 ARC-1 的植物相比，接种菌株 4.21 和 14.1 增加了胡芦巴的谷物产量。用菌株 9.17 和 14.1 处理的菜豆的谷物产量也高于未接种的和商业菌株 ARC-301。相比之下，与商业菌株 ARC-201 和 ARC-169 相比，没有一种菌株能提高豌豆和豇豆的谷物产量。在一些植物-细菌对中观察到一些农艺参数的显著增加，尽管没有观察到结瘤。接种根瘤菌对非结瘤豆科植物农艺参数的积极影响可能是由于用于接种的菌株具有促进植物生长的特性。对根瘤菌接种剂几乎完整的 16S rRNA 序列的系统发育分析表明，菌株 4.21 和 9.17 分别与 R. skierniewicense 和 R. rosettiformans 聚类，而菌株 11.2 和 14.1 与 E. meliloti 聚类。所有 4 株菌株都产生了 IAA，并对 Rhizotocnia solani、Fusarium oxysporum、Pythium ultimum、Alternaria alternata 和 Sclerotonia rolsfi 表现出生物防治活性，尽管程度不同。
