Effects of Steroids on Water Relations and Ion Uptake of Wheat Plants

Abstract

Summary Effects of the steroids, norethindrone and mestranol, on stomatal resistance, leaf water potential, leaf osmotic potential, and uptake of potassium, calcium, and iron were determined. Leaves from 20-da.y-old winter wheat plants (Triticum aestivum L. em. Theil.), grown in nutrient solution for 30 days with the steroids, were used. Stomatal resistance increased with increasing concentration of steroids. Even though steroid-treated plants had lower water potentials and osmotic potentials, compared to controls, turdigity was maintained. The steroids stimulated rooting, but inhibited potassium uptake by roots and shoots. Calcium concentrations were high in roots grown with steroids. Treated plants were slightly chlorotic, but concentrations of iron were high in roots and shoots. The effects of the steroids on the plants were similar to those reported for animals. It is suggested that 1) stomatal closure caused by the steroids might have been due to inhibition of potassium uptake, necessary for stomatal opening, 2) high calcium concentrations in the roots might have promoted cell division whidl resulted in formation of new roots, and 3) the steroids could be used as antitranspirants.