ISHS Acta Horticulturae 364: V International Rhododendron Conference
INFLUENCE OF BICARBONATE ON IRON DEFICIENCY CHLOROSIS IN RHODODENDRON |
| Authors: | A. Chaanin, W. Preil |
| Keywords: | CaCO3, lime-induced chlorosis, pH, sand culture, in vitro culture |
| Abstract:
In order to study the influence of HCO3- on iron deficiency chlorosis and root growth in Rhododendron, greenhouse and in vitro experiments were carried out using cv. 'Cunningham's White' and two clones selected for Ca-tolerance (Preil and Ebbinghaus, 1994). In one experiment ('A') the plants were grown in 11 cm plastic pots in peat and conifer-needle compost (1:1, v/v) supplemented with different amounts of CaCO3 (1, 3.5 or 17 g/l CaCO3), resulting in pH 4.2, 6.4 and 7.0, resp.. In another experiment ('B') the plants were cultivated in quartz sand watered with solutions of Ca(HCO3)2 or CaSO4 (15 and 20 meq/l). In both experiments increasing concentrations of HCO3- induced typical iron deficiency chlorosis symptoms in young leaves. In experiment 'A' root formation was completely inhibited by high levels of CaCO3, and the plants died after 4 months. The total iron content in the young leaves was low (25 – 33 μg Fe g-1 dry weight), as well as the HCI-soluble ('active') Fe content (13 – 18 μg Fe g-1 dry weight). Uptake of Mn by young leaves was also reduced at high levels of CaCO3 (6.3 – 6.9 μg Mn g-1 dry weight). Ca++ supplied as CaSO4 (experiment 'B') did not cause any chlorotic symptoms. Investigating the effect of bicarbonate on in vitro root growth 2 meq/l NaHCO3 significantly reduced root length. 10 meq/l NaHCO3 completely inhibited root formation. | |
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