STORAGE OF HARDWOOD PLANTING STOCK: EFFECTS OF VARIOUS STORAGE REGIMES AND PACKAGING METHODS ON ROOT GROWTH AND PHYSIOLOGICAL QUALITY

Abstract

Results of two experiments conducted between 1977 and 1979 on overwinter storage of seven temperate zone hardwood species commonly planted in southern Ontario indicate that temperature of storage and method of packaging can markedly affect physiological quality of planting stock. Root growth capacity and overall growth potential of cold-stored stock at 0.5 and 5°C were comparable with those of normal spring-lifted controls. Storage at temperatures of —5 and —10 °C resulted in low root growth capacity and was generally detrimental to seedling performance in comparison with spring-lifted nursery control stock that had been exposed to winter chilling out of doors. At 10°C there was considerable root and bud growth during the storage period from November to April. Of the five packaging methods examined, seedlings totally enclosed, or seedlings with only their roots enclosed within Kraft bags with a plastic liner, with moist peat surrounding the roots, showed the least shoot water stress and generally had the highest root growth capacity. Root growth capacity of stored seedlings of Acer saccharum Marsh., Acer saccharinum L., Fraxinus americana L., Quercus rubra L., Juglans nigra L., and Betula papyrifera Marsh, was significantly correlated with shoot xylem water potential at time of removal from storage. Shoot xylem water potential appears promising as a rapid measure of physiological quality. It is recommended that autumn-lifted nursery stock of Fraxinus americana, Acer saccharinum, Quercus rubra, Tilia americana L., Betula papyrifera, and Acar saccharum be stored at a temperature of 0.5°C and Juglans nigra at 5°C with a relative humidity of 70-85%. Roots should be surrounded by moist peat and the total seedling tightly enclosed within a Kraft bag with a polyethylene liner.