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| Authors: | P. Henrich, V. Romheld, H. Marschner |
Abstract:
Growth experiments were performed under controlled conditions in a climate chamber in order to identify the primary causes for iron (Fe) chlorosis in grape-vine.
In solution culture experiments, root temperature, bicarbonate concentration and content of CO2 in the air for aeration and in soil experiments temperature, water content, and bulk density of the soil were varied.
The following results were obtained: a) The chlorosis in grape-vine is primarily caused by an inhibition of uptake and translocation of Fe and not by an inactivation of Fe in the leaves. b) The decrease of Fe uptake is a result of an inhibition of root growth and root activity, particularly Fe reduction at the plasma membrane and proton release. c) The lower content of HCI-extractable Fe in chlorotic leaves is not the cause but presumably the consequence of the chlorosis. d) Precondition for chlorosis is a low Fe availability in the soil A high pH buffering capacity of the soil solution (e.g. due to bicarbonate) enhances the chlorosis.
In conclusion, the so-called bad-weather chlorosis in vine-yards is the consequence of soil compaction and high rain fall early in the growing season which lead to a delay in soil warming and elevated bicarbonate concentrations.
Both result in an inhibition of growth and activity of the roots which are important for the Fe acquisition.
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