IRON METABOLISM OF GRASSES .I. EFFECT OF IRON SUPPLY ON SOME INORGANIC AND ORGANIC CONSTITUENTS

1. The relationship of iron supply to the tissue concentration of total iron, N, HCl soluble iron, Cu, Mn, P, Ca, K, N, chlorophyll, catalase and peroxidase have been studied in two grass species raised at graded levels of iron supply ranging from 0.04-10.24 ppm in purified sand culture. 2. An increase in the iron supply caused an increase in the content of both total and acid soluble iron in Yorkshire fog up to a level of 2.56 ppm iron supply, after which no further increase took place. In timothy, low levels of iron supply caused an accumulation of both total and acid soluble iron within the tissue. 3. Increasing iron supply caused an increase in the content of chlorophyll, catalase and peroxidase. Both catalase and peroxidase were in greater concentration in Yorkshire fog than in timothy. 4. In the leaves of both species there was a marked correlation between chlorophyll and both catalase and peroxidase at all levels of iron supply. 5. Iron deficiency produced a high concentration of Cu, Mn, Ca, P, K and N in both grasses. At low levels of iron supply there was a greater accumulation of these elements in timothy than in Yorkshire fog. 6. The most reliable chemical method of identifying iron deficiency in both grasses appeared to be the value of the Ca/K, and Fe/Mn ratios. 7. A significant correlation existed between the Cu and Mn content of both grasses and suggestions are advanced to explain the susceptibility of timothy, and the resistance of Yorkshire fog to iron chlorosis with respect to the Cu and Mn contents of both grasses. © 1969 Martinus Nijhoff.