INFLUENCE OF BICARBONATE ON IRON DEFICIENCY CHLOROSIS IN RHODODENDRON
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.