Quantification of air-filled root porosity: a comparison of two methods

Air-filled porosity of the root cortex is important for aeration of roots in situations where the external oxygen is insufficient. A quantitative theory predicting the depth a vertically growing root can penetrate into the soil is now available for simultaneous internal and external oxygen transport as a function of the air-filled porosities of soil and root (De Willigen and Van Noordwijk, 1987). Maximum depth of root penetration in the soil depends on root diameter, respiration rate, conductance of root epidermis-plus-exodermis for oxygen and air-filled porosity of both soil and root. Reliable methods for quantification of the air-filled porosity of roots or root segments are needed for practical applications of this theory. Two measurement techniques will be discussed here, direct measurements on microscopic sections and the pycnometer method as described by Jensen et al. (1969). To obtain root material with the significant variation in porosity, maize plants were grown with and without aeration, including some factors stimulating or reducing the normal formation of air spaces via ethylene (Konings, 1983).

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DOI:

https://doi.org/10.1007/BF02139949

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