-Cassava is mostly planted in sandy soils which are usually of low fertility, thereby making it necessary to perform beneficial associations with microorganisms that can promote their growth. In this perspective, the possibility of selecting bacterial isolates efficient in promoting the growth of the culture is evident, which can provide subsidies for future inoculants. The objective of this study was to isolate, identify, select and evaluate the genetic diversity of endophytic bacteria in roots and stems of cassava grown in Garanhuns -PE, with features involved in promoting plant growth. The isolation was performed on culture medium semisolid LGI-P. The selected isolates were evaluated for the potential to fix N 2 , as the ability to produce indole acetic acid, for their ability to solubilize inorganic phosphate and produce exopolysaccharides. Some bacterial isolates had their 16S rRNA gene sequenced by the Sanger method. A total of 52 endophytic bacteria isolates were obtained from cassava. Regarding the potential to fix N 2 , 15% of the isolates were positive. As for the production of IAA, 78% of the isolates produced this phytohormone in a medium with increased L-tryptophan. Approximately 31% of the isolates were able to solubilize inorganic phosphate and 60% had exopolysaccharide. The identification of 19 isolates allowed the grouping into six bacterial genera, namely: Achromobacter, Bacillus, Burkholderia, Enterobacter, Pantoea and Pseudomonas. Cassava plants grown in Garanhuns -PE present interaction with different groups of endophytic bacteria and there are bacterial groups with several characteristics involved in promoting plant growth.Keywords: 16S rRNA. Exopolysaccharide. Indole acetic acid. Biological nitrogen fixation. P solubilization. BIOPROSPECÇÃO E DIVERSIDADE GENÉTICA DE BACTÉRIAS ENDOFÍTICAS ASSOCIADASA PLANTAS DE MANDIOCA RESUMO -A mandioca é, geralmente, plantada em solos arenosos e de baixa fertilidade, tornando eminente a necessidade da mesma em realizar associações benéficas com micro-organismos que possam auxiliar seu crescimento. Nessa ótica, é evidente a possibilidade de seleção de isolados bacterianos eficientes em promover o crescimento da cultura, os quais podem fornecer subsídios para futuros inoculantes. O objetivo deste trabalho foi isolar, identificar, selecionar e avaliar a diversidade genética de bactérias endofíticas de raízes e caules de mandioca, cultivada em Garanhuns -PE, com características envolvidas na promoção de crescimento vegetal. O isolamento foi realizado em meio de cultura semissólido LGI-P. Os isolados selecionados foram avaliados quanto ao potencial de fixar N 2 , quanto à capacidade de produzir ácido indol acético, quanto à capacidade de solubilizar fosfato inorgânico e produzir exopolissacarídeos.
Common bean is usually cropped under rainfed conditions and in soils with low pH and water retention, in the sub-humid and semiarid regions of Brazil. To improve soil conditions, smallholder farmers commonly use cattle manure. However, manure is available in limited amounts, insufficient to fertilize all cropping areas. Thus, other amendments, such as poultry manure (PM) and biochar (BC), have been proposed to increase soil water retention and pH. We evaluated the effects of BC (10, 20, and 40 t ha−1; BC10, BC20, and BC40, respectively), PM (5 t ha−1; PM), the combination of both amendments (BC10 + PM, BC20 + PM, and BC40 + PM) and an absolute control (Control), with no amendment, on soil physical, chemical, and biological properties, and on common bean water use efficiency (WUE) and yield. The treatments had no effects on total organic carbon, cation exchange capacity, microbial biomass carbon, soil physical properties, and evapotranspiration. Treatment combination BC (10 t ha−1) + PM (5 t ha−1) significantly improved phosphorus concentration, enzymatic activities, WUE, and bean yield in this one-year experiment and it can be a viable management practice for smallholder farmers in the Brazilian sub-humid region. However, further investigations are required to study the long-term field effects of the best performing soil amendments.
O lodo de esgoto (LE) é um resíduo sólido, oriundo de Estações de Tratamentos de Esgoto (ETE), rico em matéria orgânica, sendo capaz de melhorar as propriedades físicas, químicas e biológicas do solo. Contudo, o LE pode apresentar em sua composição elementos tóxicos e agentes patogênicos que trazem malefícios para saúde humana e para o meio ambiente. A transformação do LE, por meio do processo de pirólise, em biochar pode ser uma boa alternativa tanto do ponto de vista agrícola, quanto do ambiental. Desse modo, o presente trabalho teve o objetivo de avaliar o efeito de biochar de lodo de esgoto (BLE) na eficiência do uso da água (EUA), na evapotranspiração e na produção da cultura da alface. O experimento foi realizado em casa de vegetação, no delineamento inteiramente casualizado, utilizando-se quatro tratamentos, consistindo de controle (sem biochar), BLE10 (10 t ha-1 de BLE), BLE20 (20 t ha-1 de BLE), BLE30 (30 t ha-1 de BLE), com três repetições. Foram avaliadas a biomassa, a evapotranspiração (ET) e a eficiência no uso de água (EUA) da alface. Não foram observadas diferenças significativas na ET da alface com a adição de BLE ao solo. Contudo, verificou-se que houve um aumento crescente da produção da alface e da EUA com o aumento das doses de BLE. Assim, o BLE mostrou-se uma interessante alternativa para uma destinação adequada do lodo de esgoto gerado nas ETE. Sewage Sludge Biochar Increases Yield and Water Use Efficiency in Lettuce A B S T R A C TSewage sludge (SS) is a solid residue, originating from Sewage Treatment Plants (STP), rich in organic matter, being able to improve the physical, chemical and biological properties of the soil. However, SS can present in its composition toxic elements and pathogenic agents that bring harm to human health and the environment. The transformation of SS, through the pyrolysis process, into biochar can be a good alternative both from an agricultural and environmental point of view. Thus, the present study aimed to evaluate the effect of sewage sludge biochar (SSB) on the water use efficiency (WUE) on evapotranspiration (ET) and on the yield of lettuce. The experiment was carried out in a greenhouse, in a completely randomized design, using four treatments, consisting of control (without SSB), SSB10 (10 t ha-1 of SSB), SSB20 (20 t ha-1 of SSB), SSB30 (30 t ha-1 SSB), with three repetitions. Fresh biomass, evapotranspiration (ET) and water use efficiency (WUE) of lettuce were evaluated. No significant differences were observed in the lettuce ET with the addition of SSB to the soil. However, it was found that there was an increase in the yield of lettuce and the WUE with increasing doses of SSB. Thus, the SSB proved to be an interesting alternative for an adequate destination of the sewage sludge generated in the STPs.Key words: Waste; evapotranspiration; carbon.
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