Effects of storage temperature on physiological characteristics of fall-lifted white spruce (Picea glauca) bareroot seedlings

Fall-lifted white spruce (Picea glauca (Moench) Voss) bareroot seedlings were winter stored at -2, -4, and -6°C. The electrolyte leakage and carbohydrate content were periodically measured in roots and shoots during storage. Water relations, gas exchange, bud flushing, and root growth potentials were measured after 4 and (or) 7 months of frozen storage. Shoots and roots of seedlings stored at -6°C had higher electrolyte leakage compared with those stored at -2 and -4°C. Sugar levels increased as a result of frozen storage and were higher in seedlings stored at -4 and -6°C compared with those at -2°C. Root total nonstructural carbohydrate (TNC) contents declined with storage duration in all storage temperatures. However, seedlings stored at -4 and -6°C maintained slightly higher root TNC than those stored at -2°C. Needle TNC in seedlings stored at -4 and -6°C did not change; however, it declined in seedlings stored at -2°C. Storage temperatures of -4 and -6°C also altered seedling water relations with seedlings stored at these temperatures having lower osmotic potentials at turgor loss point and at full hydration and less elastic cell walls compared with seedlings stored at -2°C. Lower storage temperatures decreased root growth potentials and delayed bud flushing following planting.