Overcoming rest at different growth stages with hydrogen cyanamide

Abstract

Hydrogen cyanamide was effective in overcoming rest in red-osier dogwood ( Cornus sericea L.) at specific growth stages. The concentration of hydrogen cyanamide needed to overcome rest was dependent on the growth stage. From the onset of rest to maximum rest 1.0–2.0 M hydrogen cyanamide favored earlier and larger numbers of bud break. During the post-rest period 1.0 M hydrogen cyanamide was the best concentration to enhance faster and greater bud break. During the quiescent period, hydrogen cyanamide delayed the time and reduced the number of bud break. Hydrogen cyanamide had no effect on stem elongation. The growth that occurred when hydrogen cyanamide was applied at the onset of rest to maximum rest was short (rosette-like). Applications of hydrogen cyanamide after this stage of development produced elongated shoots similar to the growth of controls during normal spring growth. These studies suggest that the role of hydrogen cyanamide in breaking rest is to enhance early bud break and not shoot elongation.