Biology and Fertility of Soils

, Volume 29, Issue 4, pp 379–385

Microsensor analysis of oxygen and pH in the rice rhizosphere under field and laboratory conditions

  • N. P. Revsbech
  • O. Pedersen
  • W. Reichardt
  • A. Briones
ORIGINAL PAPER

DOI: 10.1007/s003740050568

Cite this article as:
Revsbech, N., Pedersen, O., Reichardt, W. et al. Biol Fertil Soils (1999) 29: 379. doi:10.1007/s003740050568

Abstract

 O2 and pH microsensors were used to analyse the microdistribution of O2 and pH inside and outside roots of lowland rice (Oryza sativa L.). The roots of 3-week-old transplants had O2 concentrations of about 20% air saturation at the surface, but due to a high rate of O2 consumption in the rhizosphere, the oxic region only extended about 0.4 mm into the surrounding soil. Also the fine lateral roots created an oxic zone extending about 0.15 mm into the soil. The O2 concentration within the roots approached air saturation close to the base, but only about 40–60% of air saturation in a region about 8 cm below the base where lateral rootlets were present. A shift from air to N2 around the leaves led to a drop of 50% in the O2 concentration after 12 min at a distance of 8.5 cm from the base. Flowering plants did not export O2 to the soil from the majority of their roots, but high microbial activity was present in a very thin biofilm covering the root surface. A brown colour around the thin lateral roots indicated some O2 export from these also during flowering. No oxidized zone was present around the roots at later stages of crop growth. The roots caused only minor minima in pH (<0.2 pH units) in the rhizosphere as compared to the bulk soil. Illumination of the plants had no effect on rhizosphere pH.

Key words Oxygen pH Rhizosphere Microsensor Rice 

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • N. P. Revsbech
    • 1
  • O. Pedersen
    • 2
  • W. Reichardt
    • 3
  • A. Briones
    • 3
  1. 1.Department of Microbial Ecology, Institute of Biological Sciences, University of Aarhus, Building 540, DK-8000 Aarhus C, DenmarkDK
  2. 2.Freshwater Biology Laboratory, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, DenmarkDK
  3. 3.International Rice Research Institute, P. O. Box 933, 1099 Manila, The PhilippinesXX

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