STUDIES IN PLANT MINERAL NUTRITION: III. THE EFFECTS OF CALCIUM CONCENTRATION IN CULTURE SOLUTIONS UPON THE ABSORPTION OF IRON AND MANGANESE BY DWARF KIDNEY BEAN

摘要

Definite relationships between the absorption of iron, manganese, and calcium were revealed in experiments with dwarf kidney beans grown in complete nutrient solutions containing various concentrations of iron and manganese, and two concentrations of calcium. The effects of these treatments upon the leaf contents of iron and manganese were determined by spectrophotometric analysis.It was found that increase in the concentration of either one of the metals, iron or manganese, relative to the concentration of the other, in the culture solution, appeared to depress the concentration of the other in the leaves, regardless of calcium level in the solution. Further, increase in the calcium level appeared to depress the accumulation by the leaves of both iron and manganese, regardless of their concentrations in the culture solution and the ratio between them.The iron to manganese concentration ratio in the culture solution was a factor in determining the presence or absence of deficiency symptoms. With 42ensp;p.p.m. of calcium in the culture solution, healthy plants resulted within an optimum iron: manganese ratio range of approximately 0.5 to 5.0, whereas, in the case of 143ensp;p.p.m. of calcium, healthy plants resulted only when the ratio was 2, indicating a narrower optimum range for the higher calcium level. Iron: manganese ratios below the optimum range resulted in iron deficiency symptoms, and above this range, in manganese deficiency symptoms.The data suggest that a minimum content of each of the metals, iron and manganese, must be present in the leaf tissues in order that healthy plants may result.