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Iron deficiency studies of sugar beet using an improved sodium bicarbonate-buffered hydroponic growth system

Campbell, S.A., Nishio, J.N.
Journal of plant nutrition 2000 v.23 no.6 pp. 741-757
Beta vulgaris, iron, hydroponics, buffers, screening, pH, hydrogen ions, chelating agents, oxidoreductases, roots, sodium bicarbonate, nutrient deficiencies, genotype
A sodium bicarbonate (NaHCO3)-buffered hydroponic growth system was developed that simulates alkaline soil growth conditions necessary to screen sugar beet genotypes for iron (Fe) efficiency character. Three genotypes (NB1, NB4, and F1 hybrid, NB1 x NB4) with differing capacities for Strategy I Fe responses were phenotyped successfully using this system. Genotypes NB1 and NB1 x NB4 are Fe efficient, while NB4 is Fe inefficient. It was demonstrated that 5 mM NaHCO3 provided buffering within an optimal range (pH 7.3-pH 6.3) for the duration of -Fe treatments, promoted enhanced H+ extrusion, and increased the in vivo capacity for Fe3+ -chelate reduction (Fe3+ -chelate reductase [FCR]activity], especially in the roots of the Fe efficient genotypes. The same concentrations of NaHCO3 did not interfere with Fe supply to +Fe control plants of any genotype. The in vivo capacity for Fe3+ -chelate reduction increased over fivefold in both Fe efficient genotypes (NB1 and NB1 x NB4), but just under twofold in the Fe inefficient genotype (NB4). Localization and duration of enhanced Fe3+ -chelate reduction capacity were dependent upon the Fe efficiency character of each genotype.