Influence of co-inoculation of Bradyrhizobium japonicum and Pseudomonas fluorescens on growth of soybean (Glycine max L.)

Soybean (Glycine max L.) is a very important legume in the human diet as well as fodder crop. Previous studies have reported that co-inoculation with PGPR (plant growth-promoting bacteria) and rhizobia promotes symbiotic nitrogen fixation efficiency, increases plant nitrogen content and reduces the occurrence of soybean diseases, thus reducing pesticide use, and protecting the environment. The aim of this study was to determine the impact of co-inoculation of soybean seeds with different strains of nodule bacteria Bradyrhizobium japonicum as well as PGPR (Pseudomonas fluorescens). Indigenous strains of beneficial bacteria used in this research were isolated from different locations in Croatia. Isolates were identified by performing 16S rRNA gene sequencing. The application of different strains of nodule bacteria resulted in a statistically justified effect on all investigated properties, with the exception of root length. A positive influence of P. fluorescens on the increase in shoot dry weight was observed with the co-inoculation with the reference strain B. japonicum and two indigenous strains. The application of P. fluorescens did not show statistically justified differences in any of the investigated properties. Co-inoculation of nodules and PGPR bacteria is a very important biotechnological tool in agriculture, which is why research in this area should definitely be continued and expanded to a larger number of P. fluorescens strains

Co-inoculation of soybean seed with indigenous strains of Bradyrhizobium japonicum and Pseudomonas fluorescens

Soja predstavlja jednu od vodećih ratarskih i ekonomski važnih kultura u svijetu. Predsjetvena bakterizacija soje osigurava opskrbu dušikom prirodnim putem te time umanjuje potrebu za unosom mineralnih gnojiva. Velike klimatske promjene su potaknule selekciju kultivara soje te sojeva kvržičnih bakterija s ciljem prilagodbe novonastalim ekološkim uvjetima. Selekcija autohtonih sojeva kvržičnih bakterija igra važnu ulogu u većem iskorištavanju procesa biološke fiksacije dušika, jer predstavlja vrijedan genentski potencijal određene važne poljoprivredne regije. Pravilan odabir bakterijskog soja osigurava raniju i efikasniju infekciju i nodulaciju te optimalno usvajanje atmosferskog dušika. Cilj ovoga istraživanja je utvrditi utjecaj inokulacije soje sa različitim sojevima kvržičnih bakterija i korisnim bakterijama koje pospješuju rast biljaka, te koji će se od autohtonih sojeva kvržičnih bakterija pokazati najefikasniji u nodulaciji soje. U svrhu istraživanja proveden je pokus u kojemu su korišteni autohtoni sojevi kvržičnih bakterija izolirani sa različitih lokacija Hrvatske te Pseudomonas fluorescens kao bakterija koja promovira rast biljaka. Rezultati istraživanja pokazali su kako je ko-inokulacija kvržičnih i PGPR bakterija primjer iskorištavanja korisnih mikroorganzama u uzgoju soje te se kao takav može smatrati jednim od vrlo značajnih alata biotehnologije u sustavima održive poljoprivrede.Soybean is one of the world's leading agricultural and economically important crops. Soybean inoculation can provide natural supply of plants with nitrogen, thereby reducing the need for input of synthetic fertilizers. Large climate changes have encouraged selection of soybean cultivars and strains of nodule bacteria that would adapt to new ecological conditions. Selection of indigenous rhizobial strains plays an important role in soil microbiology, as it represents valuable genetic potential from a certain agricultural region. Proper bacterial strain selection can provide an earlier and more effective infection, nodulation and fixation of atmospheric nitrogen. The aim of this research was to determine the impact of soybean inoculation with different strains of nodule and PGPR bacteria, and to establish which of the indigenous strains will provide the most effective soybean nodulation. For this purpose vegetation pot experiment was conducted in which indigenous rhizobial strains isolated from different regions Croatia and bacterium with plant growth promoting abilities – Pseudomonas flurescens were tested. The result of the study showed that soybean co-inoculation with nodule bacteria and PGPR is a example for positive relationship between microorganisms and legumes that can be considered as one of the important tools of biotechnology in sustainable agricultural systems

The Storage Efficiency of Immobilized Bradyrhizobium japonicum Strain Using Encapsulation Method

There is a growing need for new formulations of carriers with better protection for bacterial inoculum. One of the newer techniques in inoculum making is encapsulation method. With this method, the whole bacterial cells are immobilized in defined space – matrix, where the cells are protected from environmental activities before use. Encapsulation of the inoculum was performed with ionic gelation method. The alginate-based microparticles (500-600 µm) containing viable B. japonicum strain were solidified in CaCl2. The initial number of viable bacteria in every sample was 9.0 log CFU/ml. Chitosan coated particles had a higher mortality rate than non-coated particles, with 1.3 log CFU/ml in lyophilized and wet microparticles stored at room temperature. High viability of B. japonicum was registered in wet particles stored at constant −20°C for thirty days with a viability rate of 8.84 log CFU/ml