Inhibition of iron-stress reactions in sunflower [Helianthus annuus] by bicarbonate
1981
Venkatraju, K. | Marschner, H. (Hohenheim Univ., Stuttgart (Germany, F.R.). Inst. fuer Pflanzenernaehrung)
In a calcareous soil the growth rate of sunflowers was depressed by latent iron deficiency. These reactions were delayed and much less distinct than those observed under latent iron deficiency in water culture experiments. Addition of magnesium bicarbonate to this soil increased the iron deficiency of the plants and caused chlorosis, but prevented these iron-stress reactions. Distinct iron-stress reactions could be observed with latent iron-deficiency in sand culture in which varied amounts of inorganic iron (3+) were supplied. These reactions were only observed, however, in absence of bicarbonate. Bicarbonate depressed both short-term uptake of 59(Fe) as well as total iron content of the leaves. No evidence for an additional "inactivation" of iron within the leaves due to bicarbonate treatment. Bicarbonate also strongly depressed the manganese content of the young leaves. Sunflower under iron-stress-increase hydrogen efflux and reducing capacity of the roots and thus enhanced uptake of iron (and manganese) - is severely inhibited or even blocked by high bicarbonate concentrations.
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