Tratamiento con vapor altera bacterias rizoféricas asociadas a crisantemo
2008
Suárez, A., Institute of Biology, Universidad de Antioquia, Colombia | Ramírez, M., Institute of Biology, Universidad de Antioquia, Colombia | Pérez, J., Institute of Biology, Universidad de Antioquia, Colombia | Cardona, N., Institute of Biology, Universidad de Antioquia, Colombia | Calle, J., Institute of Biology, Universidad de Antioquia, Colombia | Ramírez, C., Institute of Biology, Universidad de Antioquia, Colombia
Steam treatment of soils is common in production of chrysanthemum in Colombia. Although highly effective, the beneficial effect shortly disappears, as plant growth and vigour are reduced after the first harvest, without disease symptoms or isolation of pathogens. As result, growers re-apply steam frequently, increasing production costs and potentially damaging soil health. It was hypothesized that reduced plant growth, following steam treatment, is associated with increases in deleterious bacteria. To test this hypothesis, populations of total culturable and aerobic endosporeforming (AEFB) bacteria and fluorescent pseudomonads were determined in rhizosphere soil during three different planting cycles after steam treatment and compared to populations in a control chrysanthemumcultivated soil supporting satisfactory plant growth and lacking any history of steam treatment. Significantly higher populations of all three groups were recorded in the third round of planting. However, for the second round, when the plant growth (high and fresh weight) was already significantly reduced, only increases in fluorescent pseudomonads were significant. For the first round after steam treatment, when plant growth was optimum, the populations of total bacteria and AEFB were higher in treated than in non-treated soil, whereas fluorescent pseudomonads were similar. Significant negative correlations were found between plant growth and the population of each of the bacterial groups evaluated, and the correlation coefficient was greatest for fluorescent pseudomonads. Tests for potential bacterial deleterious traits have revealed a higher proportion of indole-acetic acid-producing morphotypes of fluorescent pseudomonads in treated soils, whereas similar numbers were found for HCN production.
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