Effects of early spring photosynthesis on carbohydrate content, bud flushing and root and shoot growth of Picea glauca bareroot seedlings

摘要

The effects of early spring photosynthesis were studied in 2-yr-old white spruce (Picea glauca) bare rooted seedlings (about 30 cm tall) growing in nursery beds at the Pine Ridge Forest Nursery at Smoky Lake in Alberta, Canada. Before spring lifting, one group of seedlings was covered in nursery beds from 25 March to 18 April, 1994. The second group, used as the control, was left uncovered. The third experimental group consisted of autumn-lifted seedlings that were removed from frozen storage on March 25, 1994 and placed in nursery beds. The fourth group were autumn-lifted seedlings that remained in frozen storage. Carbohydrate analyses were made on all groups of seedlings on 7 and 18 April 1994. Seedlings from the first 2 groups (covered and uncovered) were also studied for root growth potential just before planting out in the forest (on 10 May 1994); bud flushing and field growth of these seedlings was recorded in 1994 and 1995. On 18 April, 1994, uncovered seedlings had higher levels of nonstructural carbohydrates in needles and roots than covered seedlings. Autumn-lifted seedlings placed outside in spring also had higher total nonstructural carbohydrates in needles and roots than seedlings that remained in frozen storage. Covered and uncovered seedlings had similar root growth potentials before planting, but after planting in the forest uncovered seedlings showed higher root growth rates and terminal shoot growth in the second year following planting than covered seedlings. Terminal buds flushed earlier in field planted covered than uncovered seedlings in 1994, but flushing behaviour was similar in the 2 groups in 1995.