Rhisosphere Bacteria Biotechnology Laboratory
Effect of inoculation of Siberian soya bean seeds with bacteria.
1 - control Siberian variety IKM-315;
2 - nodule bacteria;
3 - nodule bacteria and
pseudomonads
Strains of rhizosphere bacteria of the Pseudomonas genus were selected from natural populations. Based on the results of many year field and exploitation trials (the Novosibirsk region, the Altai territory), the strains appear to be promising as agents stimulating the growth of plants and their protection from phytopathogens in extreme ecological conditions of Siberia.
Under different cultivation conditions of bacteria (nutritional factors, temperature, growth rate), the studied strains differed in the biosynthesis of indolyl-3-acetic acid (IAA) known to stimulate the development of the plant root system. Some strains increased the production (or secretion) of IAA, when glucose, tryptophan, growth hormones and other supplements were added to the culture medium, other strains produced IAA intensely without the additives, virtually not responding to their presence. IAA was assayed at different phases of bacterial growth in culture medium and in cell mass (1 ml/cell) and 1 mg of protein by immunoenzyme analysis.
The differences in IAA production between the strains were consistent with their plant growth-promoting effect (seed inoculation before sowing, spraying the vegetating plants or aerosol technology). Treatment resulted in an 15-25% increase in the yield of cultivars. The beneficial effect varied depending on the climatic conditions and season of the year.
The capacity of the studied strains to suppress the growth of various pathogens varied, and it was not related to the specificities of IAA production.
The characteristic features of some of the strains and the results of their tests on cultivars have been described in patents of the Russian Federation 1 2130261, 2130262, 2130263 of 30.09.1997, 12130264 of 15.12.1997, 12130265 of 29.12.1997.