“NEAR-LETHAL” STRESS EFFECTS ON ENDO DORMANCY, COLD ACCLIMATION, AND RECOVERY OF RED-OSIER DOGWOOD PLANTS.

Abstract

“Near-lethal” (NL) stresses from varied sources, e. g. NL-heat (47°C-lhr), NL-freeze (-7°C -lhr), and NL-hydrogen cyanamide (0.5-1 M), overcame endo-dormancy in red-osier dogwood (Cornus sericea L.) plants. Near-lethal heat stress applied at early rest (Oct.) had a slight effect on cold acclimation, whereas at late rest (Dec.), NL-stress resulted in the rapid loss of hardiness at warm or natural environment conditions. Recovery of plants from NL-stresses was dependent on the stage of development and temperature. Less dieback occurred with later stage of endo-dormancy, and at warmer temperatures. Dormant plants in October exposed to other NL-stresses, e. g., freezing temperature and hydrogen cyanamide, also caused plant dieback at 0°C and recovered at 23°C post-environment treatment. Conditions that favored recovery also favored production of glutathione.