SOME OBSERVATION ON AIR-ION-ENHANCED IRON CHLOROSIS IN BARLEY (HORDEUM VULGARIS) SEEDLINGS

Abstract

The air ion effects on “active” and “residual” iron distribution in barley seedlings were studied in the course of the development of ironchlorosis in an iron-free culture medium. “Active” or “acid soluble” iron plays an important role for chlorophyll biosynthesis and is extractable with 1.0 N HCl from dried tissues, and “residual” or “acid insoluble” iron does not participate in this chlorophyll formation process and is not extracted with 1.0 N HCl. Ions of either charge induced a significant decrease in active iron content which was associated with a decrease in chlorophyll content. Concomitantly, there occurred an increase in both the residual iron and the cytochrome c fractions. The increase in residual iron content may involve not only cytochrome c but also other cytochromes and ironcontaining enzymes as well. The authors have proposed a hypothesis that the site of air ion action in the experiments reported may be the regulatory systems controlling iron metabolism in the seed and young seedling. Through this action air ions apparently divert more endogenous free-state iron to residual iron (consisting of cytochromes and Fe-containing enzymes) than to active iron. Tracer experiments showed that air ions enhanced the uptake of exogenous iron by early germinating barley seeds. The increased incorporation of iron was not influenced by light.