Effects of inoculation with plant growth promoting rhizobacteria (PGPRs) andSinorhizobium fredii on biological nitrogen fixation, nodulation and growth ofGlycine max cv. Osumi

Abstract

We investigated the effects of three plant growth promoting rhizobacteria (PGPR), on Biological Nitrogen Fixation (BNF), nodulation and growth promotion by soybean (Glycine max) var. Osumi plants. The strains, Aur 6, Aur 9 and Cell 4, belong to Psedomonas fluorescens, Chryseobacterium balustinum and Serratia fonticola, respectively. Inoculation modes for the PGPRs and Sinorhizobium fredii (carried out through irrigation), were examined. In the first mode, PGPRs and S. fredii were co-inoculated. In the second mode, we first inoculated S. fredii and after the PGPRs, which were added 5 or 10 days later (each inoculation being an independent treatment). In the third mode, the PGPRs were inoculated first, and the S. fredii was inoculated 5 days later. We also included treatments inoculated with only the PGPRs (one PGPR per treatment) and only with S. fredii. Plants were maintained in a greenhouse under controlled environmental conditions, and were sampled 3 months after sowing. The results obtained showed the effects of the inoculation sequence. The most significant effects on growth parameters (stem plus leaf weight and fresh root weight) were found when inoculations with PGPR and S. fredii were at different times or when we inoculated only with PGPR and the plants were watered with nitrogen. Co-inoculation had no positive effects on any parameter, probably due to competition between the PGPR and S. fredii. Our results indicate that the inoculation modes with PGPR and rhizobia play a very important role in the effects produced. Thus, although plant growth promoting rhizobacteria may interact synergistically with root-nodulating rhizobia, plant growth promoting rhizobacteria selected for one crop should be assessed for potentially hazardous effects on other crops before being used as inoculants.

Potential of Herbaspirillum and Azospirillum Consortium to Promote Growth of Perennial Ryegrass under Water Deficit

“…Some authors have also observed this behavior and have concluded that the competition between bacteria could alter their ability to colonize the rhizosphere. Lucas García et al [ 51 ] found that the sequence of the inoculation of bacterial strains altered the growth-promoting effect of Pseudomonas fluorescens , Chryseobacterium balustinum , Serratia fonticola , and Sinorhizobium fredii . In their study, inoculating the S. fredii strain first and the other strains five days later resulted in a synergistic effect on plant growth, which was not observed by co-inoculating the strains at the same time.…”

Paving the Way From the Lab to the Field: Using Synthetic Microbial Consortia to Produce High-Quality Crops

“…Currently, the typical SMC often include PGPB and AMF, targeting to enhance the metabolites contents (e.g., essential oil, zein, glucosinolate, sugar, ascorbic and folic acid, volatile compounds, vitamin, and anthocyanin) and nutrients (N, Ca, P, Mg, K, Na, Fe, Mn, Cu, Zn, and B), which represent higher nutraceutical values in crops (Hart and Forsythe, 2012 ; Berta et al, 2014 ; Cosme et al, 2014 ; Bona et al, 2015 , 2017 ; Hart et al, 2015 ; Weisany et al, 2015 ; Battini et al, 2016 ; Torres et al, 2016 ; Avio et al, 2017 ). However, previous studies dealing with SMC have reported a range of plant responses and contradictory results (Lucas García et al, 2004 ; Estévez et al, 2009 ; Rosier et al, 2016 ), suggesting that different microbes may not have additive effects. Importantly, the compatibility within microbes and with new environment is an essential consideration for constructing SMC.…”

Selection of Plant Growth-Promoting Pseudomonas spp. That Enhanced Productivity of Soybean-Wheat Cropping System in Central India

“…Hence, the interaction between the plant root zone and rhizobacteria may have profound influence on crop health and soil quality [69]. It is in this context that the impact of Pseudomonas inoculants has been evaluated on many agronomically important crops such as beans, peanut, soybean, and wheat, resulting in increased growth and yield [3,15,19,39]. Such beneficial effects are possibly due to build-up of inoculant in the rhizosphere as detected by changes in soil enzymatic activities and through a multitude of direct and indirect mechanisms [44,79].…”