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Hungria M.,Embrapa Soja | Nogueira M.A.,Embrapa Soja | Araujo R.S.,Total Biotecnologia Industria e Comercio Ltda
Agriculture, Ecosystems and Environment | Year: 2016

Estimates are that in Brazil there are about 180 million hectares of pasturelands, 70% with some degree of degradation. Reclamation of such areas demands re-establishment of soil fertility, plant growth and forage production, and microbial inoculants might help in these processes. We evaluated the ability of two strains of Azospirillum brasilense to promote the growth of two genotypes of Brachiaria spp. (=Urochloa spp.). The experiments were set up at three different sites in Brazil, and forage production estimated for 26 cuts in two years. On average, increases of 5.4% and 22.1% in response to N-fertilizer alone and to N-fertilizer in combination with Azospirillum, respectively, were observed over the non-inoculated and non-N-fertilized control treatment. Increase in N accumulation in the biomass in response to Azospirillum was equivalent to a second application of 40 kg of N-fertilizer ha-1. Estimates attributed to the inoculation were of gains of 0.103 Mg C ha-1, corresponding to 0.309 Mg CO2-eq ha-1. Inoculation with Azospirillum may represent a key component of programs to reclaim degraded pastures and help sequestration of CO2 from the atmosphere. © 2016 Elsevier B.V. Source


Hungria M.,Embrapa Soja | Hungria M.,Brazilian National Council for Scientific and Technological Development | Nogueira M.A.,Embrapa Soja | Nogueira M.A.,Brazilian National Council for Scientific and Technological Development | And 2 more authors.
Biology and Fertility of Soils | Year: 2013

Plant-microorganism associations have long been studied, but their exploitation in agriculture partially or fully replacing chemical fertilizers is still modest. In this study, we evaluated the combined action of rhizobial and plant growth-promoting rhizobacteria inoculants on the yields of soybean and common bean. Seed inoculation with rhizobia (1.2 × 106 cells seed-1) was compared to co-inoculation with Azospirillum brasilense in-furrow (different doses) or on seeds (1.2 × 105 cells seed-1) in nine field experiments. The best in-furrow inoculant dose was 2.5 × 105 cells of A. brasilense seed-1 for both crops. Inoculation with Bradyrhizobium japonicum increased soybean yield by an average 222 kg ha-1 (8.4 %), and co-inoculation with A. brasilense in-furrow by an average 427 kg ha-1 (16.1 %); inoculation always improved nodulation. Seed co-inoculation with both microorganisms resulted in a mean yield increase of 420 kg ha-1 (14.1 %) in soybean relative to the non-inoculated control. For common bean, seed inoculation with Rhizobium tropici increased yield by 98 kg ha-1 (8.3 %), while co-inoculation with A. brasilense in-furrow resulted in the impressive increase of 285 kg ha-1 (19.6 %). The cheaper, more sustainable inoculated treatment produced yields equivalent to the more expensive non-inoculated + N-fertilizer treatment. The results confirm the feasibility of using rhizobia and azospirilla as inoculants in a broad range of agricultural systems, replacing expensive and environmentally unfriendly N-fertilizers. © 2013 Springer-Verlag Berlin Heidelberg. Source


Fukami J.,Embrapa Soja | Fukami J.,State University Londrina | Nogueira M.A.,Embrapa Soja | Araujo R.S.,Total Biotecnologia Industria e Comercio Ltda | And 2 more authors.
AMB Express | Year: 2016

The utilization of inoculants containing Azospirillum is becoming more popular due to increasing reports of expressive gains in grain yields. However, incompatibility with pesticides used in seed treatments represents a main limitation for a successful inoculation. Therefore, in this study we searched for alternatives methods for seed inoculation of maize and wheat, aiming to avoid the direct contact of bacteria with pesticides. Different doses of inoculants containing Azospirillum brasilense were employed to perform inoculation in-furrow, via soil spray at sowing and via leaf spray after seedlings had emerged, in comparison to seed inoculation. Experiments were conducted first under greenhouse controlled conditions and then confirmed in the field at different locations in Brazil. In the greenhouse, most parameters measured responded positively to the largest inoculant dose used in foliar sprays, but benefits could also be observed from both in-furrow and soil spray inoculation. However, our results present evidence that field inoculation with plant-growth promoting bacteria must consider inoculant doses, and point to the need of fine adjustments to avoid crossing the threshold of growth stimulation and inhibition. All inoculation techniques increased the abundance of diazotrophic bacteria in plant tissues, and foliar spray improved colonization of leaves, while soil inoculations favored root and rhizosphere colonization. In field experiments, inoculation with A. brasilense allowed for a 25 % reduction in the need for N fertilizers. Our results have identified alternative methods of inoculation that were as effective as the standard seed inoculation that may represent an important strategy to avoid the incompatibility between inoculant bacteria and pesticides employed for seed treatment. © 2016, Fukami et al. Source


Hungria M.,Embrapa Soja | Nakatani A.S.,Embrapa Soja | Souza R.A.,Embrapa Soja | Sei F.B.,Santa Catarina State University | And 3 more authors.
Transgenic Research | Year: 2014

Studies on the effects of transgenes in soybean [Glycine max (L.) Merr.] and the associated use of specific herbicides on biological nitrogen fixation (BNF) are still few, although it is important to ensure minimal impacts on benefits provided by the root-nodule symbiosis. Cultivance CV127 transgenic soybean is a cultivar containing the ahas gene, which confers resistance to herbicides of the imidazolinone group. The aim of this study was to assess the effects of the ahas transgene and of imidazolinone herbicide on BNF parameters and soybean yield. A large-scale set of field experiments was conducted, for three cropping seasons, at nine sites in Brazil, with a total of 20 trials. The experiment was designed as a completely randomized block with four replicates and the following treatments: (T1) near isogenic transgenic soybean (Cultivance CV127) + herbicide of the imidazolinone group (imazapyr); (T2) near isogenic transgenic soybean + conventional herbicides; and (T3) parental conventional soybean (Conquista) + conventional herbicides; in addition, two commercial cultivars were included, Monsoy 8001 (M-SOY 8001) (T4), and Coodetec 217 (CD 217) (T5). At the R2 growth stage, plants were collected and BNF parameters evaluated. In general, there were no effects on BNF parameters due to the transgenic trait or associated with the specific herbicide. Similarly, at the final harvest, no grain-yield effects were detected related to the ahas gene or to the specific herbicide. However, clear effects on BNF and grain yield were attributed to location and cropping season. © 2014, Springer International Publishing Switzerland. Source

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