Iron, the Limiting Element in a Chlorosis: Part I. Availability and Utilization of Iron Dependent upon Nutrition and Plant Species

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Abstract
Four plant species which differed in their susceptibility to "lime-induced" chlorosis (Fe deficiency) and Cu deficiency were grown in soils of low available Fe supply (calcareous) and soils of low available Cu supply (organic). A continuous source of available Fe appeared necessary for the growth of all the plants studied, but the plant species differed in the concn. of available Fe required in the growth media to prevent chlorosis. One of the 4 species was unable to absorb sufficient Fe from calcareous soil for normal growth. Radioiron was supplied to chlorosis-susceptible soybeans through approach grafts and seed. In each case, insufficient Fe was absorbed from the soil to prevent chlorosis when the available source was stopped or depleted. The radioiron in the plant did not move appreciably under these conditions. The available Cu supply in the growth media seemed to have a marked effect upon the absorption and utilization of Fe by corn. Iron accumulated throughout the Cu-deficiency plant (especially in the nodes) and the addition of Cu to the soil decreased this absorption. Both vars. of soybeans and wheat differed from corn in this respect. Wheat developed severe Cu-deficiency symptoms, corn only moderate symptoms, and the soybeans did not respond to Cu. The physiology of the plant, as detd. by plant species or variety, and as influenced by the mineral nutrition of the soil, determines in a large measure the status of Fe in the plant.