© 1995 Heron Publishing—Victoria, Canada
Effects of cold storage and water stress on water relations and gas exchange of white spruce (Picea glauca) seedlings
Yong Jiang (1), S. Ellen MacDonald (2) and Janusz J. Zwiazek (2)
1. School of Forest Resources, University of Georgia, Athens, GA 30602, USA / 2. Department of Forest Science, University of Alberta, Edmonton, Alberta T6G 2H1, Canada / Received March 16, 1994
Summary
To determine the effects of lifting time and storage on water-stress resistance of nursery-grown white spruce (Picea glauca (Moench) Voss) seedlings, we compared gas exchange, water relations and mortality of 3-year-old seedlings lifted in October
1991 and stored at –2 °C for 3 months with seedlings lifted in January 1992. The seedlings were placed in nutrient solution
and subjected to –1.1 or –2.7 MPa water stress induced by polyethylene glycol 3350 for 9 days. Water stress, but not lifting
time, had a significant effect on seedling net assimilation, symplastic volume and turgor loss point. In a second experiment,
seedlings lifted in October 1991 were stored at –2 °C for 7 months and compared with seedlings lifted in May 1992. The seedlings
were planted in pots, and their gas exchange and water relation parameters measured in response to gradual water stress. The
results suggest that prolonged cold storage retards photosynthetic recovery of seedlings after planting. Higher rates of net
assimilation in seedlings lifted in May were not directly related to their water status. Nonstomatal limitations were the
primary factor influencing photosynthetic rate. We conclude that the inferior ability of cold-stored seedlings to tolerate
water stress was due to poor osmotic adjustment and a lag in recovery of photosynthesis.
Keywords:
net assimilation, mesophyll conductance, stomatal conductance, water use efficiency.
