Atividades enzimáticas na rizosfera de espécies leguminosas nativas mediadas por rizobactérias e micorrizas arbusculares

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Early soil-quality indicators may be useful when monitoring plant reestablishment, especially in degraded environments. Among soil-quality indicators, soil enzymes may reflect the potential in turning some nutrients available for plants, since most of them are related to nutrients transformation in soil. Besides the intrinsic effects of vegetation on soil enzymes, microbial associations may also change their activities, either directly or indirectly due to changes on plant physiology. The objective of this work was to assess the activity of eight enzymes (acid phosphatase, alkaline phosphatase, dehydrogenase, asparaginase, urease, glutaminase, cellulase and amylase) in addition to the hot water soluble carbohydrates (HWCH) in the rhizosphere of four native woody leguminous species when associated to arbuscular mycorrhizal fungi (AMF) and rhizobacteria. The experimental design was entirely randomized in a 4x5x2 factorial arrangement: four leguminous species (Anadenanthera colubrina, Enterolobium contortisiliquum, Parapiptadenia rigida and Peltophorum dubium, a non-noduliferous species), used in reforestation programs in southern Brazil; five mycorrhizal status (Glomus clarum, G. etunicatum, G. intraradices, Gigaspora margarita and a non-mycorrhizal control); with or without rhizobacteria (Rhizobium sp. or Burkholderia sp. in the non-noduliferous species), in four replications in a greenhouse experiment using 2-kg pots containing low-fertility sandy soil. The best plant growth was found in the associations with G. clarum and G. margarita, while the rhizobacteria effects were less pronounced. Plant species was the factor that most affected the enzyme activity, but the microbial inoculation (AMF or rhizobacteria) also caused some effects, stimulating or decreasing enzyme activity, depending on the plant species. Among the four plant species, the nonnoduliferous P. dubium showed a more active rhizosphere when associated to AMF and rhizobacteria. A more biochemically active rhizosphere may confer to this plant an ecophysiological advantage when used in reclamations of degraded and lowfertility environments. A principal component analysis (PCA) showed that P. dubium and P. rigida had similar enzymatic activities in their rhizospheres, while E. contortisiliquum and A. colubrina showed dissimilar patterns of enzymatic activities, independently of microbial inoculation.

ASSUNTO(S)

soil microorganism vesicular-arbuscular mycorrhiza leguminosae rhizosphere solo - microbiologia micorriza vesículo-arbuscular microorganismos do solo rizosfera leguminosa

ACESSO AO ARTIGO

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