engleski

Competition for alfalfa nodule occupancy between introduced strains of Sinorhizobium meliloti and indigenous population in soil and its influence on plant production

Inoculation of legume crops with rhizobia has been widely used in agricultural systems to improve legume productivity in the field. However, commercially available rhizobial inoculants often fail to become established in soils with indigenous rhizobial populations. In this respect, the selection of more effective and highly competitive Sinorhizobium meliloti strains for alfalfa inoculation is necessary. The main objective of this study was to evaluate competitive abilities of two different S. meliloti inoculants in the soil, as well as its influence on plant growth promotion. For this purpose, two factor pot experiment was carried out under controlled conditions using completely randomized block design. The factors of the experiment were indigenous S. meliloti strains exhibiting different symbiotic efficiency and three different alfalfa development stages. Nodule occupancy by the two introduced S. meliloti strains was studied by ERIC-PCR DNA fingerprinting. In the treatment inoculated with more effective S. meliloti strain (OS6) it occupied 64 % of the nodules tested, while less effective strain (S26) was present only in 22, 5 % of the nodules. These results were confirmed using 16S rDNA sequences analysis, showing that predominance of OS6 strain in nodules also proves their better competitive ability in comparison with indigenous strains present in the soil. The positive effect of inoculation with a highly effective strain was confirmed in most of the investigated parameters related to the plant. These results suggested that the highly effective S. meliloti OS6 strain, investigated in this study, could be promising candidate for improving alfalfa yield and quality.

Simbiotic nitrogen fixation; Sinorhizobium meliloti; Alfalfa

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