Storage duration and temperature effect on the functional integrity of container and bare-root Pinus radiata D. Don stock-types

We have investigated the effect of storage conditions (duration: 1, 8 or 15 days; temperature: 4°C or 10°C) and root coverage [bare root (BR) or soil-plugged root (PR)] on the water status, electrolyte leakage and root growth potential (number of new roots and new root length) of radiata pine (Pinus radiata D. Don) seedlings. We have also examined the effects that storage causes on plant quality and initial survival potential and their usefulness for detecting physiological damage to seedlings. We observed a gradual decrease of seedling water status and an increase in electrolyte leakage, both in root and shoot, with duration of storage, the latter indicating damage to membranes. Both storage temperature and duration influenced the ability of radiata pine seedlings to initiate and elongate new roots. The effect was more pronounced in BR than in container seedlings, suggesting that the rooting-plug medium provides protection against desiccation. The close relationship (r=0.923, P<0.05) between root growth potential and predawn xylem water potential before transplanting shows that water potential at the time of transplanting is a reliable predictor of the ability to generate new roots. Finally, we have observed a close relationship between survival and parameters such as electrolyte conductivity, post-storage water potential, new root length and root growth potential.