root pruning, wrenching and overwinter cold storage : effects on the morphological and physiological condition of transplant picea glauca [moench] voss nursery stock
abstract
the objectives of this thesis were to; 1) evaluate the
effect of a single early spring root pruning followed by a
series of five root wrenching treatments at three week
intervals on the morphological condition of rising 2+2
white spruce nursery stock, 2) to determine the effect of
wrenching and several overwinter cold storage environments
on bud dormancy progression, root regenerating potential
and planting stock performance, 3) to assess wrenching as
a method of conditioning bare root nursery stock for fall
lifting and overwinter cold storage.
root pruning and wrenching was applied to rising 2+2
white spruce in nursery trials one in 1982 and another in
1983 at the ontario ministry of natural resources forest
station, thunder bay ontario. the root pruning and
wrenching treatment reduced current height increment,
reduced the number of primordia in the winter buds, and in
1983 significantly increased root area index. root
pruning and wrenching increased the overall root
regenerating potential of stock during overwinter cold
storage. wrenching and root pruning did not significantly
alter bud dormancy progression or patterns of root
regeneration during the winter.
both the control and the root pruned and wrenched
stock was overwinter cold stored in 3 storage
environments. the progression of bud dormancy and root
regeneration potential of this stock was monitored monthly
for a seven month period during the winter. stock that
was fall lifted and overwinter stored had the same winter
bud dormancy pattern as stock overwintered in the nursery
bed but a different pattern of root regenerating
potential. cold storage delayed bud flushing in the
spring and prevented frost damage from occuring after
spring outplanting. a six week spring warm up
conditioning treatment at +2 c in cold storage increased
root regenerating potential. the exposure of fall lifted
stock to natural photoperiods while overwintering in an
unheated polyhouse did not appear to improve planting
stock quality over that of the same stock overwintered at
-2 c in complete darkness.
collections
- retrospective theses [1604]