Beziehungen zwischen Chlorosegrad, Eisengehalten und Blattwachstum von Weinreben auf verschiedenen Standorten

Abstract

Relationship between chlorosis, iron and leaf growth in grapevines growing at different locations

At different locations, samples from chlorotic and green leaves were taken periodically during the growing season. Leaf area, contents of chlorophyll, total iron and acid-soluble iron were determined in leaf samples from various positions within the shoots.
At locations where chlorosis became evident during the growth period, analysis showed that these leaves had lower levels of both total iron and acid-soluble iron compared with leaves of locations without chlorosis. At all locations, a close linear correlation was found between the contents of acid-soluble iron and chlorophyll. For total iron this positive correlation was confined to the lower concentration range (50-90 μg Feig dry weight). The highest and lowest contents of total iron and of acid-soluble iron were found in the youngest leaves and in the leaves with the largest growth rate, respectively. This demonstrates 'dilution' and 'concentration' effects of iron in the leaf dry matter. Therefore, particular care is necessary in leaf sampling as a basis for causal interpretations of iron chlorosis.
The results of the present study indicate that the lower uptake and translocation rates of iron rather than the 'inactivation' of iron within the shoots are responsible for chloros is at the various locations.