CHEMICAL COMPOSITION OF ALFALFA AS RELATED TO DEGREE OF TOLERANCE TO MANGANESE AND ALUMINIUM

Abstract

In an attempt to study the nature of plant tolerance to soil acidity and related factors, a series of investigations was conducted with sand cultures to determine the chemical composition of alfalfa as related to its response to various concentrations of manganese, aluminium and calcium. All clones studied were affected, but to a variable degree, by an excess of manganese and aluminium. They absorbed approximately the same amounts of these elements but considerable differences were noted in their rate of translocation from the roots to the aerial organs. As a result, plants which were the least affected by manganese and aluminium contained smaller amounts of those two elements in their stems and leaves and larger amounts in their roots. Moreover, for a given content of manganese and aluminium in aerial organs, the degree of injury was approximately the same for all clones. More total and water-soluble calcium was found in so-called tolerant than non-tolerant plants. Also, an increase in the calcium concentration of the nutrient culture was effective in reducing manganese toxicity. These results suggest the theory that the rate of uptake of calcium by the plant is one of the factors determining its degree of tolerance to manganese and aluminium.