Establishment and early growth of black spruce (Picea mariana [Mill.] B.S.P.) in relation to selected nursery lifting and storage practices

Abstract

Problems associated with the establishment and early growth of overwinter frozen stored black spruce {Picea mariana [Mill.] B.S.P.) seedlings led to research on the effects of selected nursery lifting and storage practices on post-planting performance. The broad objective was to evaluate important physiological and morphological response attributes of fall lifted, overwinter frozen stored, spring lifted, cool stored, and freshly lifted 1V2 + 1 V2black spruce transplants during concurrent potting and field trials established in May and June, 1987. The potting trials were conducted in a controlled environment chamber under two soil water regimes (well-watered vs. water stressed). The outplanting trials were conducted on a cultivated nursery soil and the scarified soil of a regional outplanting site. The nursery trial included undisturbed (i.e. not planted, thinned in situ), control seedlings as an additional treatment. The research conducted under controlled environment conditions indicated that the selected liftingstorage treatments affect early plant water relations through interactions with both root growth capacity and stomatal function. Most importantly, the fall lifted seedlings exhibited prolific root growth but showed poor stomatal control over transpirational losses. In contrast, the spring lifted seedlings showed poorer root growth but maintained better stomatal control over transpirational losses. Shoot-tissue water relations determined using the pressure-volume technique varied between lifting-storage treatments, water regimes, and potting times and often showed a lack of agreement between the selected parameters. Pre-potting osmotic potentials at full turgor and the turgor loss point increased between potting times for all seedlings. In general, post-planting osmotic potentials were lower for the water stressed than well-watered seedlings and increased with renewed bud and shoot activity. Physiological response differed between the fall and spring lifted seedlings under field conditions and generally compared with the results of the potting trials. After one growing season, the undisturbed seedlings were clearly larger than any of the outplants, particularly the spring lifted, stored seedlings. Regardless of variations in physiological and morphological response, all seedlings showed acceptable growth and survival after one growing season.