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STUDIES ON OXYGEN TRANSPORT THROUGH MUSTARD SEEDLINGS ( SINAPIS ALBA L.)
Author(s) -
GREENWOOD D. J.
Publication year - 1967
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1967.tb05431.x
Subject(s) - oxygen , sinapis , limiting oxygen concentration , oxygen transport , chemistry , botany , atmosphere (unit) , horticulture , biology , physics , organic chemistry , brassica , thermodynamics
S ummary The entry of oxygen into various organs and the transport of oxygen through plant tissues was studied. Seedlings had their roots embedded in agar‐gel to exclude oxygen. The gas atmosphere around a part of the plant was changed from nitrogen to oxygen and the subsequent increase in oxygen concentration at a point on the root surface was measured. Changing the atmosphere around the stems and leaves induced rises in oxygen concentrations throughout the length of the roots to the root tips. An equation derived by assuming that transport was by gaseous diffusion and was large in comparison with metabolic uptake, fitted the increases in oxygen concentration at points on the roots within 3 cm of the stems, but not at the root tips. The discrepancy was accounted for by the greater value of metabolic uptake relative to oxygen transport at the root tips than near the stems. Thus all the results were consistent with oxygen diffusing through gas spaces within the plants. Removing all the leaves restricted the entry of oxygen into the aerial portions of the plants, but the extent to which it did so was reduced by subjecting the seedlings to water stress and was less with old than with young seedlings. Excising the leaves was considered to release cell sap which blocked the gas channels. Exposure of either the stem or a segment of root to oxygen resulted in a small amount of oxygen being transported along the roots. Oxygen transport from the aerial portions of the plant to a point on the roots, 1–2 cm from the hase of the stems, was almost independent of (a) the aeration conditions of the growth media; (b) the mechanical impedence to root growth offered by the media; (c) root length; (d) shoot length; (e) age of plant.