The effect of stage of growth on the copper, zinc, manganese, and molybdenum contents of Algerian oats grown of thirteen soils

Abstract

Algerian oats were grown on 13 soils in the glass-house. Plants were harvested at intervals throughout the growing period, and when large enough were divided into leaf, stem, and (in later harvests) flowers or fruits. Copper, zinc, manganese, and molybdenum were determined on the separate plant fractions. Characteristic changes in the trace metal contents of the plant with growth were found for each element. These changes were generally similar irrespective of the soil on which the plants were grown. With the exception of manganese, the availability of the element in the soil did not affect the trend of the changes as the plant matured, but only the amount present. The uptake of each of the four elements continued through the whole period of growth. The total amounts of copper and zinc in both the leaf and the stem decreased after flowering as translocation to the grain proceeded. The amount of manganese in the leaf increased throughout the period of growth, although the rate of increase was less after flowering. The amount of molybdenum in the leaf increased until flowering, after which there was little further change. The rate of uptake of manganese was approximately equal to the rate of production of dry matter, whereas that of molybdenum, copper, and zinc was relatively greater in the early stages of growth. There was no observable influence of soil pH on the availability of copper and zinc, but that of manganese decreased with increasing pH. The availability of molybdenum was affected by the combined influences of soil pH and soil iron.