BICARBONATE ION AND OXYGEN LEVEL AS RELATED TO CHLOROSIS

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Abstract
Soil solns. from chlorotic areas had a higher concn. of HCO3 and Ca ions than did those from green areas. Great Northern beans were grown in soln. cultures containing combinations of NaCl or NaHCO3 at 10 me./l.; ion phosphate or iron sequestrene; and aerated with 2 1/2, 5, and 20% O2 mixtures. The HCO3 ion reduced the movement of radio-iron into the leaves and stems and accentuated its accumulation in the roots. Chlorosis in HCO3-treated cultures increased at the high O2, levels. This condition was accompanied by reduced movement of Fe to the leaves, lower chlorophyll, and reduced growth. Fe sequestrene was only a slightly more efficient source of Fe to bean plants in soln. cultures at pH 7.8 than was soluble iron phosphate. The increase of plant chlorosis frequently associated with poorly aerated conditions cannot be primarily attributed to a reduced O2 level at the roots.