Abstract
Sugarcane has a high demand in nitrogen, increasing costs and causing damages to the environment. It is necessary to find alternatives to reduce nitrogen fertilizers use. Diazotrophic bacteria have capacity to promote growth in grass with potential to fix N2 and solubilize inorganic phosphate. This study aimed to evaluate bacterial community associated with different sugarcane varieties in Northeastern Brazil, select bacteria with plant growth-promoting characteristics, and identify endophytic and epiphytic bacterial lineages in sugarcane. Endophytic bacteria of leaves and roots and epiphytic bacteria of rhizoplane were isolated from three sugarcane commercial varieties and selected for their capacity to fix N2 and solubilize inorganic phosphate. Bacterial strains from different morphological groups were isolated and a sample of 27 strains with potential for the simultaneous development of these characteristics were selected and identified. The bacterial community that interacted with sugarcane was more associated with rhizoplane and roots regions than with leaves, and had a high potential to fix N2 and solubilize inorganic phosphate. Bacterial lineages were mainly from genera Pantoea sp. and Burkholderia sp., but there were also genera Enterobacter sp., Klebsiella sp. and Pseudomonas sp. and two lineages at the species level: Pantoea stewartii and Burkholderia cenocepacia. Key words: Plant/bacteria interaction, plant growth-promoting bacteria, N2 fixing bacteria, bacteria identification.
Highlights
This study aimed to evaluate bacterial community associated with different sugarcane varieties in Northeastern Brazil, select bacteria with plant growth-promoting characteristics, and identify endophytic and epiphytic bacterial lineages in sugarcane
Total population densities of the bacterial community associated with the sugarcane varieties RB 92579 and RB 863129 were similar, and higher compared with RB 867515 (Table 1)
Herbicide application was necessary in the area cultivated with RB 867515, which may have compromised the bacterial colonization in this variety
Summary
Resende et al (2006) reported that biological N2 fixation (BNF) performed by bacteria associated with sugarcane can be responsible for up to 60% of the total N accumulated in the plants. This means that BNF can contribute to reducing the use of N fertilizers, especially for the production of sugarcane in the first crop cycle (Polidoro et al, 2006; Resende et al, 2006)
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