Increasing the temperature of the water soak preceding moist-chilling promotes dormancy-termination of seeds of western white pine (Pinus monticola Dougl.)

Abstract

Seeds of western white pine (Pinus monticola Dougl.) exhibit a very pronounced and deep primary dormancy at maturity which often leads to erratic germination after the implementation of dormancy-breaking treatments. Toward increasing the efficiency of dormancy-breakage and improving the rate and synchronicity of germination, the effectiveness of various modified pre-chilling and chilling treatments were determined using five seedlots of western white pine. Treatments that combined chemicals (hormones or anaesthetics such as gibberellic acid and 1-propanol) with moist chilling were not effective in accelerating dormancy termination. Control of seed moisture content during chilling through the use of solid matrix priming was not effective in eliciting high germinability and proved more deleterious especially for longer chilling periods. The most effective treatment to terminate dormancy was an increased-temperature water soak prior to moist chilling. At an optimum temperature of 27°C, a 12-day water soak could effectively shorten the requirement for moist chilling by approximately 20-30 days (from 96 to 75 or 60 days).