The Absorption and Translocation of Iron.

Iron has been recognized as an essential element for quite some time, yet much of the data concerning the uptake and translocation of this element by plants is conflicting or incomplete. Three factors have emerged, however, as being highly influential in the process of iron absorption. These factors are pH, phosphorus concentration, and the chemical form of the iron. OLSEN (7) has indicated that high pH and high phosphorus concentration of the nutrient solution induce iron deficiency chlorosis. He also suggested that too high a phosphorus concentration could cause a precipitation of iron along the veins of the leaf. FRANCO and LooMIs (2) somewhat more recently have shown that iron absorption from cultures is reduced by phosphorus, especially at pH 6 or higher. The effect of various forms of iron on iron uptake has been investigated in a relative sense, the data being concerned primarily with those forms of iron giving the best growth under a given set of conditions. Iron has long been commonly referred to as a non-mobile element. Indeed, GILE and CARRERO (4) at a very early date conducted an experiment with rice which demonstrated this immobility. However, since that time, the work on iron translocation has been sparse and incomplete. The present paper is concerned with those factors which have been shown to effect the absorption and translocation of iron, namely, pH, phosphorus concentration and the amount and chemical form of the iron used. An attempt has been made to define the effects of these factors in a quantitative sense and to determine interrelations between them.