Isolation and phenotypic characterization of soybean (Glycine max L.) microsymbionts in continental Croatia | Izolacija i fenotipska karakterizacija mikrosimbionata soje (Glycine max L.) u kontinentalnoj Hrvatskoj

English. Symbiotic nitrogen fixation enables legumes to supply most of their needs for nitrogen in efficient and ecological manner. Rhizobia are group of prokaryotic organisms with the unique ability to form symbiotic relationships at the root of leguminosis in which they inert atmospheric nitrogen in plants is converted by nitrogenase enzymes. It is assumed that native rhizobial populations are also present in the soils of continental Croatia and that the strains differ from each other in phenotypic and genotypic properties. In order to select the best rhizobia strains, soil samples were collected from three areas of continental Croatia where there is a long tradition of soybean cultivation. Phenotypic characterization included the determination of growth at different temperatures, pH values and growth at different salt concentrations, biochemical characterization, antibiotic resistance testing. Phenotypic characterization has shown significant resistance to environmental stress conditions, particularly resistance to low pH, which is extremely important because Croatia has a lot of acid soils. Strains SR1, SR2 and SR3 have proven to be the best strains, therefore it would be useful to include them in a further selection programme.

Croatian. Simbioznom fiksacijom dušika leguminoze mogu zadovoljiti veliki dio svojih potreba za dušikom na učinkovit i ekološki prihvatljiv način. Rizobije su skupine bakterija tla sa jedinstvenom sposobnošću tvorbe kvržica na korijenu leguminoza u kojima pomoću enzima nitrogenaze konvertiraju inertan atmosferski dušik u biljkama pristupačan amonijačni oblik. Pretpostavlja se da su u tlima kontinentalne Hrvatske prisutni autohtoni sojevi rizobija koji noduliraju soju te da se sojevi međusobno razlikuju po fenotipskim i genotipskim svojstvima. U cilju odabira najkvalitetnijih sojeva rizobija sakupljeni su uzorci tla iz tri područja kontinentalne Hrvatske u kojem postoji dugogodišnja tradicija uzgoja soje. Fenotipska karakterizacija uključila je utvrđivanje rasta na različitim temperaturama, pH vrijednostima i rast na različitim koncentracijama soli, biokemijsku karakterizaciju, ispitivanje otpornosti na antibiotike. Fenotipska karakterizacija pokazala je značajnu otpornost na stresne uvjete okoliša, posebno otpornost na niski pH što je izuzetno važno jer Hrvatska ima jako puno kiselih tala. Kao najbolji sojevi pokazali su se sojevi SR1, SR2 te SR3 zbog čega bi ih bilo korisno uključiti u daljnji program selekcije.