Growth and Nutrient Uptake by Barley (Hordeum vulgare L. cv Herta): Studies Using an N-(2-Hydroxyethyl)ethylenedinitrilotriacetic Acid-Buffered Nutrient Solution Technique (II. Role of Zinc in the Uptake and Root Leakage of Mineral Nutrients)

Abstract

adequately with Zn; they also leaked significant amounts of Zn even though the seedlings were not supplied Zn during growth.Calculated uptake rates of P, Mn, and Na were sharply reduced, but uptake rates of K and M g were stimulated by increasing the ZnZ+ activity in nutrient solutions. lntact roots of Zn-deficient seedlings contained lower concentrations of 5,5'-dithio-bis(2-nitrobenzoic acid) reactive sulfhydryl groups in comparison to Znadequate roots. Apparently, Zn is required for the uptake and retention of severa1 mineral nutrients by roots, possibly by playing a protective role in preventing the oxidation of sulfhydryl groups to disulfides in root-cell plasma membrane proteins involved in ion channel-gating phenomena.

Iron Deficiency-Induced Secretion of Phenolics Facilitates the Reutilization of Root Apoplastic Iron in Red Clover

“…The probable mechanism for this process might be as follows: the secreted phenolics react with Fe fixed in apoplast, making the Fe available for absorption by the root cells and translocation to the shoot. Fe deficiency usually can enhance the uptake of other metal elements (Welch and Norvell, 1993;Cohen et al, 1998;Chen et al, 2004). Here, we also found that the concentrations of Mn, Cu, and Zn in both shoots and roots were higher when phenolics were removed (with the exception of Mn in roots; Fig.…”

Effects of zinc activity in nutrient solution on uptake, translocation, and root export of cadmium and zinc in three wheat genotypes with different zinc efficiencies

“…Insufficient solution Zn 2þ activity may be an important factor in enhanced Cd accumulation by plants even when Zn is applied at sufficient levels to prevent Zn deficiency. Under insufficient Zn 2þ activity the ability to adequately regulate ion transport processes of plasma membranes is reduced Welch and Norvell 1993). Impaired integrity of root plasma membrane may be accompanied by an increase in Cd uptake.…”

Zinc Requirement for Stomatal Opening in Cauliflower

“…Increased plasma membrane permeability in the roots of Zn-deficient plants results in a decreased K+ content due to enhanced K+ efflux (Cakmak and Marschner, 1990;Welch and Norvell, 1993). However, no information is available on the effect of Zn deficiency on the flux of K+ across the guard cell membranes.…”

“…Deficiency of Zn affects the integrity of plasma membranes, which become low in phospholipids and sulfhydryl groups and show enhanced production of superoxide radicals (Cakmak and Marschner, 1988;Welch and Norvell, 1993;Pinton et al, 1994). Increased plasma membrane permeability in the roots of Zn-deficient plants results in a decreased K+ content due to enhanced K+ efflux (Cakmak and Marschner, 1990;Welch and Norvell, 1993).…”