The role of sucrose and nitrogen in adventitious root formation on cultured rose shoots

Cultured shoots ofRosa ‘Improved Blaze’ were used to determine the effects of sucrose and inorganic nitrogen on adventitious root formation. Shoots grown in media containing high sucrose concentrations (146.07–262.93 mM) produced more and longer roots than those grown in media containing 0–87.64 mM sucrose. This response to sucrose was related to the metabolism of sucrose rather than its osmotic properties since the use of mannitol and 3-O-methyl-α-D-glucopyranoside as osmotic substitutes did not reproduce the effect on rooting. The number and length of roots increased when the shoots were grown in media with the nitrogen concentration of the Murashige-Skoog (MS) salt formulation reduced from 60 to 7.5 mM. Neither nitrate (NO ₃ ⁻ ) nor ammonium (NH ₄ ⁺ ) alone at any of the concentrations tested had the effect on rooting that both had together in the ratio of the MS salt formulation. When the sucrose and nitrogen concentrations were both varied, the greatest rate of root initiation occurred on shoots grown in media with a high sucrose to nitrogen concentration ratio.