Significant Rôles of Trace Elements in the Nutrition of Plants

Abstract

During the past quarter of a century much has been written concerning the place of the so-called trace elements in the economy of plant life. Most of this literature deals with the effects produced upon plants when these elements are absent from the growth substrate and is purely descriptive in nature, portraying the symptoms of deficiency. There is also, in the phvsiological literature of the past decade and a half, much descriptive material portraying the pathological symptoms which appear in plants when these elements oceur in the plant environment in concentrations in excess of those required for growth and development. Thus far these qualitative observations make up practically all of the great mass of the investigational literature upon this subject. So much of this foundation in natural fact has already beeni accomplished, that intensive activity along this line of categorical description can no longer be considered an adequate field of investigation in this particular phase of plant nutrition. It should be remembered, however, that the extension of our knowledge in this phase of nutrition cannot progress without at least some continued activity along these descriptive lines; but our chief interest is no longer in the qualitative pathological symptoms themselves, which develop as the result of trace element malnutrition, but in their relation to those more basic phenomena which can be evaluated only through careful quantitative experimental investigation. From almost the beginning of the present century studies have been directed toward aseertainiing, whether or not certain elements, which are found in trace quantities in both the plant and in its environment, might be included in the category of essential factors for growth and development. There is much contradictory, evidence, as might be expected, relative to this question, which 1 Journial

Distribution of Boron in Cells of Dicotyledonous Plants in Relation to Growth.

“…The physiological importance of the soluble boron fraction (cell sap obtained by mechanical pressure) in plants has been pointed out (4,5,7,8) but this fraction has generally not been further separated. Shive (8) has shown that monocotyledonous plants contain greater amounts of soluble boron than do dicotyledonous species which is perhaps the reason.…”

The Effect of Different Iron and Manganese Nutrient Levels on the Catalase and Cytochrome Oxidase Activities of Green and Albino Sunflower Leaf Tissues.

“…Seeds for the green stock plants were sown on September 30,1952, and seeds for the albino seedlings were sown 20 days later in white quartz sand. The normal seasonal daily sunlight period was extended to 16 hours with incandescent light. A minimum intensity of about 6 fc was provided.…”

Boron Stem Infusions Stimulate Soybean Yield by Increasing Pods on Lateral Branches

“…Interactions between Ca and B in the plant have long been recognized (19 (6) stated that high levels of Ca as well as high levels of K accentuate plant B-deficiency symptoms and decrease toxicity symptoms. These interactions may explain the trend toward lower yields observed in our Ca + B treatments when compared to soybeans injected with B alone.…”