STUDIES IN PLANT MINERAL NUTRITION: II. THE ABSORPTION OF IRON AND MANGANESE BY DWARF KIDNEY BEAN, TOMATO, AND ONION FROM CULTURE SOLUTIONS

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Abstract
Dwarf kidney beans and tomatoes were grown in complete nutrient solutions containing various concentrations of iron and manganese. It was found that the iron to manganese ratio in the culture solutions must be within a definite range in order to avoid deficiency symptoms in the experimental plants. For the dwarf bean this range was 1.5 to 3.0, and for the tomato it was 0.5 to 5.0. Concentration ratios outside the optimum range produced either iron or manganese deficiency symptoms. Concentrations below minimum values of both iron and manganese always produced deficiency symptoms irrespective of the ratio of iron to manganese in the culture solutions. An apparent antagonism between the absorption of iron and of manganese was observed with both beans and tomatoes grown in nutrient solutions. This antagonism was also found to occur with onions grown in solutions containing only the sulphates of the two metals. It was further found that with onions growing in single salt solutions of the sulphates of iron and manganese, the concentration of iron or manganese in the solutions did not affect the amounts of the metals absorbed by the plants from the solutions. The combined amount of iron plus manganese absorbed appeared to remain constant irrespective of the iron to manganese ratio in the culture solution.