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Oxygen uptake by roots of Rumex species at different temperatures: the relative importance of diffusive resistance and enzyme kinetics
Author(s) -
LAAN P.,
TOSSERAMS M.,
HUYS P.,
BIENFAIT H. F.
Publication year - 1991
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1991.tb01341.x
Subject(s) - rumex , oxygen , respiration , alternative oxidase , chemistry , respiration rate , botany , biology , organic chemistry
. Oxygen uptake characteristics of the roots of three Rumex species were compared, and related to kinetics of the respiratory system and to root anatomy. The observed differences could not be explained by differences in fundamental characteristics of the oxygen uptake system: with all three species, cytochrome‐mediated respiration contributed 70% and cyanide‐insensitive (alternative) respiration 30% of the total respiration rate, and apparent K m values of cytochrome oxidase were lower than those obtained for the alternative oxidase in all cases. However, differences in critical oxygen pressure for respiration (COPR) and in apparent K m for oxygen, were strongly correlated with differences in root porosity and root diameter. K m (O 2 ) values at high and low temperatures were determined, and from Arrhenius plots of oxygen uptake rates between 11 and 32°C, the role of diffusional impedance could be estimated. Root respiration of Rumex maritimus and R. crispus , both with high root porosity, but differing in root diameter, had a low K m for oxygen (3–7 mmol m −3 ). In contrast with this were the responses of R. thvrsiflorus , which has thin roots but low root porosity: a high K m (10‐20 mmol m −3 ) was found at all temperatures. The role of diffusional impedance as a function of temperature in oxygen uptake rate by the three species is discussed and related to the differential resistance of the species towards flooding.