ISOLATION AND CHARACTERIZATION OF PLANT GROWTH PROMOTING BACTERIA ISOLATED FROM GARLIC (allium sativum).

Garlic has great economic and social importance in Santa Catarina. It is a demanding crop in nutrients, being necessary high amount of chemical fertilizers, increasing the cost of production and the environmental impact. An alternative to the use of inputs are Rizobacteria Promoting Plant Growth (RPCP). Among the RPCPs, the most studied genera are Azospirillum, Bacillus and Pseudomonas of the fluorescent group that have shown benefits for the growth of several plant species. In this context, isolates of RPCP obtained from the rhizosphere of garlic maintained in protected cultivation were phenotypically and genotypically characterized and a growth promotion test in vivo was carried out, in protected cultivation. The biochemical tests used for phenotypic characterization were glucose and sucrose fermentation, Methyl Red (MR), catalase production and urea hydrolysis. The potential of plant growth induction was also evaluated by analyzing the production capacity of IAA (Indol-Acetic Acid) and calcium phosphate solubilization in vitro. Twenty-seven isolates were obtained. For the biochemical tests, 21 isolates were able to ferment glucose and 26, sucrose. For the other tests, all isolates showed a positive reaction. As for the mechanisms of plant growth promotion, 81.5% and 66.6% of the isolates presented IAA production and phosphate solubilizing capacity, respectively. The in vivo growth promotion test using maize (Zea mays) as a model indicated that the tested isolates (EB02, EB16, EB14, EB26, EB23) showed similarity to the treatment with 100% recommended nitrogen fertilization. The isolates were identified by sequencing the 16S rRNA gene. Fourteen isolates (51, 85% of the collection) were identified as Bacillus subtillis, including those tested in planta. These microorganisms present potential for the promotion of plant growth

Fluorescent Pseudomonas spp. and Bacillus spp. for phosphate solubilization and growth promotion of garlic

Garlic is a nutrient demanding crop which requires a high investment for fertilization and especially for phosphate (P) fertilizers, due to its high retention by the soil. It is possible to use the P solubilizing microbiota, especially rhizobacteria, to make P available and reduce fertilization. Fluorescent Pseudomonas spp. (CBS02) and Bacillus spp. (EB17) isolates were tested at triple superphosphate doses (0 % - without triple superphosphate; 50 % - 472.82 kg ha-1; 100 % - 945.65 kg ha-1). The experimental design was randomized blocks, in a 4 x 3 x 4 factorial scheme, with four treatments (CBS02 isolate, EB17 isolate, isolates mixture and control) and four replications. The size, fresh and dry masses, P content of the fourth leaf and yield were evaluated. The mixture of Pseudomonas spp. (CBS02) and Bacillus spp. (EB17) used in the inoculation of the garlic bulbils increased the size, dry mass and P content of the fourth leaf, as well as the yield of the crop without triple superphosphate, indicating that the P solubilization capacity of the isolates was increased when these were combined. It was possible to observe an increment in all the evaluated variables, indicating that the isolates P solubilization capacity was enhanced when they were combined

Influência da interação entre genótipos de feijoeiro e rizóbios na nodulação e fixação de nitrogênio

Bacteria from the rhizobia group are able to associate symbiotically with bean crop, forming nodules in the root, in which the biological nitrogen-fixing process occurs. However, the efficiency of this process has been low and it can be attributed to genetic and environmental factors. Thus, the objective of this study was to evaluate the capacity of nodulation of local varieties and commercial common bean cultivars inoculated with a Rhizobium tropici strain used in commercial inoculants and rhizobia isolates from common bean root nodules. The experiment was carried out in a factorial scheme (2x4), in a randomized block design with four replicates. It was tested two local varieties and two commercial cultivars, inoculated with the reference Rhizobium tropici strain CIAT899 and the RBZ14 strain isolated from common bean nodules grown in soils of Southern Brazil, in adapted Leonard-type pots. The CIAT899 strain promoted either higher mass of viable nodules and higher nitrogen accumulation in the aerial part. The black group local variety showed better response than the cultivar TAA Dama for nodule viability, suggesting more efficiency for nodulation. The interaction between genotypes (local varieties and commercial cultivars) and bacteria showed the specificity of the complex symbiotic relationship of biological nitrogen fixation in common bean, requiring further studies of these interactions.As bactérias do grupo rizóbios estão associadas simbioticamente à cultura do feijão, formando nódulos na raiz, nos quais ocorre o processo biológico de fixação do nitrogênio. No entanto, a eficiência desse processo tem sido baixa e pode ser atribuída a fatores genéticos e ambientais. Assim, este estudo teve como objetivo avaliar a capacidade de nodulação de variedades locais e cultivares comerciais de feijão comum inoculadas com uma estirpe de Rhizobium tropici usada em inoculantes comerciais e isolados de nódulos da raiz do feijão comum. O experimento foi realizado em esquema fatorial (2x4), em delineamento de blocos ao acaso, com quatro repetições. Foram testadas duas variedades locais e duas cultivares comerciais, inoculadas com a estirpe de referência Rhizobium tropici CIAT899 e o isolado RBZ14 obtido de nódulos de feijão cultivados em solos do sul do Brasil, em vasos adaptados do tipo Leonard. A estirpe CIAT899 promoveu maior massa de nódulos viáveis ​​e maior acúmulo de nitrogênio na parte aérea. A variedade regional do grupo preto apresentou melhor resposta que a cultivar TAA Dama, quanto à viabilidade dos nódulos, sugerindo resposta mais eficiente à nodulação. A interação entre genótipos e bactérias mostrou a especificidade da complexa relação simbiótica da fixação biológica de nitrogênio no feijoeiro, sendo necessário aprofundar os estudos nessas interações

Efeito de glyphosate e imazaquin na comunidade bacteriana do rizoplano de soja (Glycine max (L.) Merrill) e em características microbiológicas do solo

Práticas culturais, como a aplicação de agrotóxicos, podem interferir diretamente na comunidade microbiana do solo e naquela associada às raízes vegetais. Os efeitos, no entanto, são complexos e, na maioria das vezes, de difícil detecção, quando se utilizam técnicas convencionais na avaliação. Por outro lado, o recente desenvolvimento e utilização de métodos moleculares, baseados no DNA, têm permitido melhorar a avaliação desses efeitos muitas vezes negativos. Este trabalho teve como objetivo avaliar alterações provocadas pela aplicação de herbicidas à base de glyphosate e imazaquin no C da biomassa microbiana do solo (C-BMS), respiração basal do solo (RBS) e quociente metabólico (qCO2), bem como na comunidade bacteriana associada ao rizoplano de soja (Glycine max (L.) Merril), por meio das técnicas de eletroforese em gel com gradiente desnaturante (DGGE) e análise da região espaçadora intergênica ribossomal (RISA). Realizou-se um experimento em casa de vegetação com solo coletado em área com histórico de cultivo de soja e aplicação desses herbicidas. A C-BMS, RBS e qCO2 foram avaliadas antes da aplicação dos herbicidas e aos 2, 14, 30 e 62 dias depois desta. A comunidade bacteriana associada ao rizoplano de soja foi avaliada por DGGE e RISA aos 14, 30 e 62 dias após a aplicação dos herbicidas. Os resultados mostraram que ambos os herbicidas não ocasionaram alterações significativas no teor de C da biomassa microbiana do solo, na respiração basal do solo e no quociente metabólico; contudo, ocasionaram alterações na comunidade bacteriana associada ao rizoplano de soja, na forma de restrição do crescimento de determinadas bactérias e estímulo de outras, em todas as coletas realizadas. As similaridades entre os perfis bacterianos os tratamentos com herbicidas e o controle foram inferiores a 55 % em todas as coletas

Inoculation of Pinus taeda Seedlings with Plant Growth-promoting Rhizobacteria

<div><p>ABSTRACT The aim of this study was to evaluate the effect of Azospirillum brasilense , Bacillus subtilis and Pseudomonas fluorescens on the growth of Pinus taeda seedlings. Bacterial inoculants were applied in two different forms: at sowing and 20 days after emergence. At 30, 60 and 90 days after emergence, we evaluated plant height and root-colar diameter. At 180 days after emergence, we also measured shoot and root dry weight. Data were analyzed by analysis of variance and means were ranked by Duncan’s test. The most pronounced results were observed for root and shoot biomass when plants were inoculated with Bacillus subtilis and Pseudomonas fluorescens. Bacillus subtilis increased root and shoot biomass by 67.1% and 33.1%, respectively, when comparing values with those of non-inoculated plants. On the other hand, inoculation with Pseudomonas fluorescens decreased root biomass up to 31.42%. Inoculation with Azospirillum brasilense did not promote any difference in Pinus taeda seedling growth and may not be an efficient alternative for inoculation practices. According to these results, inoculation of Pinus taeda seedlings with Bacillus subtilis has great potential to improve plant growth regarding adaptation to field conditions.</p></div