AGAR AND AMMONIUM-NITRATE INFLUENCE HYPERHYDRICITY, TISSUE NITRATE AND TOTAL NITROGEN-CONTENT OF SERVICEBERRY (AMELANCHIER ARBOREA) SHOOTS IN-VITRO

Shoot tip cultures of Amelanchier arborea Michx.f. were grown on Muras hige & Skoog or Woody Plant (WP) medium containing 4.4 mu M benzyladen ine and various concentrations of agar. Increases in agar concentratio n affected various culture growth variables, decreased culture hyperhy dricity and increased tissue nitrate concentration. Additions of ammon ium nitrate to cultures grown on WP medium containing 0.4% agar increa sed all growth variables measured except percent dry weight. Hyperhydr icity and tissue nitrate concentration also increase in response to in creasing ammonium nitrate in the medium. Since hyperhydricity was show n to be both positively and negatively correlated with increases in ti ssue nitrate content, it is unlikely that tissue nitrate level alone d irectly affects hyperhydricity.