Improving Seed Longevity

Vegetation reclamation in oil sands requires a consistent and adequate supply of native shrub seeds. However, annual seed production is erratic and seeds are usually short lived and insufficiently abundant for reclamation projects. This project hypothesized that shrub seeds rapidly lose their viability due to respiration-related deterioration, and treatments that can reduce respiration and/or induce Late Embryogenesis Abundant (LEA) proteins and heat shock proteins prolong seed viability. To investigate pre-storage treatments and storage conditions for improving seed longevity of native shrubs for reclamation of oil sands mines, seeds of 11 native shrub species were used to analyze physiological changes during storage and artificial aging processes. They were stored for up to four years during storage under eight combinations of temperature (-20, 4, 22.5 °C), atmosphere (Air/N2) and relative humidity (seed moisture content; 7-8%/3-4%).

Room temperature with low seed moisture content and ambient conditions is recommended as optimal to store bearberry, bog cranberry, choke cherry, low bush cranberry, and pin cherry. Low storage temperature with low seed moisture content was best for blueberry, buffalo berry, dogwood, green alder and Saskatoon berry. N2 has limited effects and high costs, so is not recommended. Non-aged and aged seeds showed significantly different seedling lengths, indicating a negative effect of accelerated aging process on the seedling vigor. Electrolyte conductivity and seed dehydrin protein expression is strongly correlated with seed vigour, which can be used to predict seed longevity. The storage protocol developed in this study will help ensure adequate supply of viable shrub seeds for reclamation and the artificial aging method to predict longevity can be extended to other non-crop species used in oil sands reclamation. Further research on effective dormancy-breaking methods, reliable techniques for seed viability determination and species-specific thermal time requirements is needed.