ROLE OF RYE CHROMOSOMES IN IMPROVEMENT OF ZINC EFFICIENCY IN WHEAT AND TRITICALE

Using the disomic wheat-rye addition lines (Triticum aestivum L., cv. Holdfast-Secale cereale L., cv. King-II) and an octoploid triticale li ne (xTriticosecale Wittmark L. ''PlutoxFakon'') as well as the respect ive wheat and rye parents, greenhouse experiments were carried out to study the role of rye chromosomes on the severity of Zn deficiency sym ptoms, shoot dry matter production, Zn efficiency, shoot Zn concentrat ion and Zn content. Plants were grown in a Zn-deficient calcareous soi l with (10 mg Zn kg(-1) soil) and without Zn supply. Zinc efficiency w as calculated as the ratio of dry weight produced under Zn deficiency to the dry weight produced under Zn fertilization. In the experiments with addition lines, visual Zn deficiency symptoms were slight in the rye cultivar King-II, but were severe in the wheat cultivar Holdfast. The addition of rye chromosomes, particularly 1R, 2R and 7R, into Hold fast reduced the severity of deficiency symptoms. Holdfast showed high er decreases in shoot dry matter production by Zn deficiency and thus had a low Zn efficiency (53 %), while King-II was less affected by Zn deficiency and had a higher Zn efficiency (89 %). With the exception o f the 3R line, all addition lines had higher Zn efficiency than their wheat parent: the IR line had the highest Zn efficiency (80 %). In the experiment with the triticale cultivar and its parents, rye cv. Pluto and wheat cv. Fakon, Zn deficiency symptoms were absent in Pluto, sli ght in triticale and very severe in Fakon. Zinc efficiency was 88 % fo r Pluto, 73 % for triticale and 64 % for Fakon. Such differences in Zn efficiency were better related to the total amount of Zn per shoot th an to the amount of Zn per unit dry weight of shoot. Only in the rye c ultivars, Zn efficiency was closely related with Zn concentration. Tri ticale was more similar to rye than wheat regarding Zn concentration a nd Zn accumulation per shoot under both Zn-deficient and Zn-sufficient conditions. The results presented in this study show that rye has an exceptionally high Zn efficiency, and the rye chromosomes, particularl y 1R and 7R carry the genes controlling Zn efficiency. To our knowledg e, the result with triticale and its rye parents is the first report s howing that the genes controlling Zn efficiency in rye are transferabl e into wheat and can be used for development of new wheat varieties wi th high Zn efficiency for severely Zn-deficient conditions.