Mechanism of Physiological Effects of Titanium Leaf Sprays on Plants Grown on Soil STANISLAV KUZ ˇEL,* ,1 MARTIN HRUBY, 2 PETR CÍGLER, 3 PAVEL TLUSTOS ˇ, 4 AND PHU NGUYEN VAN 4 1 Faculty of Agriculture, South Bohemian University, Department of General Plant Production, C ˇ eské Bude ˇjovice, Czech Republic; 2 Institute of Macromolecular Chemistry, Prague, Czech Republic; 3 Department of Analytical Chemistry, Institute of Chemical Technology, Prague, Czech Republic; and 4 Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture, Prague, Czech Republic Received April 25, 2002; Accepted June 6, 2002 ABSTRACT Titanium (Ti) has significant biological effects on plants, being bene- ficial at low and toxic at higher concentrations. From results of our hydro- ponical experiment with oats, we have recently proposed that the effect called hormesis is the mechanism of Ti action in plants. Here, we present the experiment with oats (Avena sativa L. cv. Zlat’ák) grown on soil where Ti was applied using leaf sprays. Two different soils, three different concen- trations of Ti(IV) citrate spray solution (0, 20, and 50 mg Ti/kg), and three different Mg concentrations in each soil were tested. Some physiological parameters (dry and raw weights, top heights, chlorophyll content) and element contents (Mg, Fe, Zn, Mn) were determined. Ti showed consider- able effects on all physiological parameters and the element’s contents were determined. Differences between the two different soil types used was only in the strength of the effect of Ti; the trends remained unchanged. Generally, the effect of Ti is considerably weaker if Ti is applied on leaves than if being added to the nutrient solution. Thus, we confirm here that the action of Ti on plants could be explained by the hormesis effect. Index Entries: Titanium; oats; plant; magnesium; manganese; zinc; iron; chlorophyll; leaf, spray. Biological Trace Element Research 179 Vol. 91, 2003 © Copyright 2003 by Humana Press Inc. All rights of any nature, whatsoever, reserved. 0163-4984/03/9102–0179 $20.00 *Author to whom all correspondence and reprint requests should be addressed.