Growth, survival, and physiology of Douglas-fir seedlings following root wrenching and fertilization

1983 ◽  
Vol 13 (2) ◽  
pp. 270-278 ◽  
Author(s):  
R. van den Driessche

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were subjected to wrenching treatments during their 2nd year of growth in two experiments at different nurseries on Vancouver Island. Seedlings were wrenched with a fixed blade at 20–25 cm below the bed surface. In experiment 1 wrenching reduced water potential of trees on unirrigated loam soil by an average of 300 kPa during August and September. Wrenched trees lifted in October, which were stored at 2 °C until May, showed 25% higher survival than unwrenched trees 1 year after planting. Trees lifted in December had uniformly high survival (98%) and showed no effect of wrenching. Wrenched trees from irrigated plots had lower shoot length relative growth rates (RGR) than unwrenched trees during the year after planting. In experiment 2 wrenching treatments were applied to seedlings, growing in a loamy sand, for different periods between 15 May and 11 September as follows: (i) unwrenched, (ii) early summer, (iii) midsummer, (iv) late summer, (v) all summer. Three different levels of fertilization were applied to each wrenching treatment, and seedlings were lifted for storage at 2 °C in October and December. Stored trees and freshly lifted trees were planted at 700 m elevation on 3 March. Wrenching increased root dry weight, particularly when additional fertilizer was applied, but had no measurable effect on cold hardiness or root growth capacity. Nevertheless, late summer wrenching increased survival 5 and 7% above control 1 and 2 years after planting, when average survival was 47% after 1 year. Wrenching had little subsequent effect on new shoot growth of planted trees during 2 years after planting. However, late summer wrenched trees showed significantly more new shoot growth than all summer wrenched trees. Increasing fertilization reduced cold hardiness and survival of cold-stored trees, but increased root growth capacity. Cold hardiness, measured by electrical impedance, was correlated with survival of cold-stored trees after planting (r2 = 0.82). Root growth capacity, averaged over all fertilizer levels, was closely correlated with survival of stored and freshly lifted trees (r2 = 0.93). Foliar nutrient concentrations were reduced by wrenching, but fertilization increased nutrient reserves within the seedling.

1992 ◽  
Vol 22 (5) ◽  
pp. 740-749 ◽  
Author(s):  
R. van den Driessche

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings, each represented by two seed lots, were grown in Styroblock containers in a greenhouse and plastic shelter house from February 1989 to January 1990. The seedlings were exposed to two nitrogen (N) treatments and three potassium (K) treatments arranged factorially within three drought treatments. After winter storage, seedlings from a complete set of treatments were planted into hygric, mesic, and xeric sand beds during 12–14 March. Increasing nursery drought stress increased survival of Douglas-fir and lodgepole pine after planting, and high N treatment level increased survival of lodgepole pine and white spruce. Under xeric conditions, combined nursery drought and high N treatments increased survival of lodgepole pine by 33%, indicating the importance of nursery cultural regime for stock quality. Increase in nursery drought decreased seedling size relatively little, but increase in N increased seedling size one season after planting. A positive relationship between shoot/root ratio and survival in lodgepole pine and white spruce indicated that increase in N increased both shoot growth and drought resistance over the N range investigated. Only Douglas-fir showed an interaction between drought and N treatment and a small response in both survival and dry weight to K. Root growth capacity, measured at the time of planting, showed an approximate doubling in all species due to high N treatment, and was also increased in white spruce by drought stress. Survival and root growth capacity were poorly correlated, but dry-weight growth in sand beds was well correlated with root growth capacity. Shoot dry weight and percent N in shoots measured after nursery growth were correlated with root growth capacity. Manipulation of root growth capacity by changing nursery treatment was apparently possible without altering resistance to drought stress after planting.


1984 ◽  
Vol 14 (5) ◽  
pp. 644-651 ◽  
Author(s):  
A. N. Burdett ◽  
L. J. Herring ◽  
C. F. Thompson

Observations were made on the growth of white spruce (Piceaglauca (Moench) Voss) and Engelmann spruce (P. engelmanni Parry), each planted at a single location in the interior of British Columbia. In both species bareroot stock (either 2 + 0 seedlings or 2 + 1 transplants) with a low root growth capacity made only limited height growth during the first two seasons after planting. In the first season, many short stem units were formed, whereas in the second season, stem units were much longer but many fewer. The length of needles formed after planting by the bareroot trees was, in the first season, only about half that of needles formed the previous year in the nursery. Needle length increased slightly in the 2nd year. Container-grown trees (1 + 0 seedlings from 336-mL containers), which had a high root growth capacity, made relatively good height growth in the first season when they formed long needles and stem units. Height growth by these seedlings was much less in the second season, however, as were needle length and stem unit number, but not stem unit length. Application of slow release N,P, and K fertilizer at planting improved shoot growth by bareroot trees more in the second season than the first. In contrast, the container-grown stock made a large shoot growth response to fertilization in both the first and the second seasons. The results are consistent with the hypothesis that, as root establishment proceeds, shoot growth tends to be limited by the supply, first of water, then of mineral nutrients. This implies that the early growth of planted spruce can be maximized by using stock with a high root growth capacity, or other adaptations to drought, and applying slow release fertilizer at planting. Observations on the white spruce revealed an acceleration in shoot growth by both stock types during the third season. This followed the establishment, by the end of the second season, of root systems several metres in diameter. A large difference in height: diameter ratio, observed at the time of planting, between the container-grown and bareroot white spruce disappeared entirely in the course of the first three growing seasons.


1987 ◽  
Vol 17 (8) ◽  
pp. 768-775 ◽  
Author(s):  
A. N. Burdett

Laboratory assays for measuring the root growth capacity (RGC) of forest tree seedlings were first developed in the belief that root extension immediately after planting is a major determinant of establishment success. An assumption underlying the development of these tests was that root growth under standardized conditions in the laboratory is indicative of root growth under the generally quite different and often highly variable conditions in the field. Evidence in support of this assumption is slight. Recently, it has been proposed that RGC affects seedling performance, not directly, but by virtue of a correlation with cold hardiness or other types of stress resistance that directly affect performance. For this hypothesis, also, the evidence is slight. There is a need for a clearer understanding of the relationship between RGC and seedling establishment to decide how best to measure and interpret RGC as a gauge of stock quality. This is illustrated by a discussion of the optimum conditions for measuring RGC and of the quantitative relationship between RGC and early performance of planted stock.


1990 ◽  
Vol 20 (5) ◽  
pp. 566-572 ◽  
Author(s):  
David G. Simpson

Interior spruce (Piceaglaucaengelmannii complex), lodgepole pine (Pinuscontorta Dougl.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and western hemlock (Tsugaheterophylla (Raf.) Sarg.) were grown from seed for 20 weeks in containers, with 18-h photoperiods. Fortnightly, over a 12-week acclimation period (September 7 – December 1) outdoors at Vernon, B.C., samples were taken for (i) foliage frost hardiness measurement, (ii) poststorage root growth capacity, and (iii) outplanting on forest sites. In all species, frost hardiness and root growth capacity increased with weeks of acclimation. Frost hardiness and root growth capacity were correlated with each other in western hemlock, lodgepole pine, and Douglas-fir, and with field performance (survival or growth) in interior spruce, lodgepole pine, and Douglas-fir.


1985 ◽  
Vol 15 (4) ◽  
pp. 625-630 ◽  
Author(s):  
Anne M. Johnson-Flanagan ◽  
John N. Owens

Root growth in the root systems of Styroplug-grown white spruce (Piceaglauca (Moench) Voss) seedlings increases in the spring before shoot elongation and again in the fall after bud development is complete. This is followed by root dormancy and quiescence, which are distinguished on the basis of ability to elongate under root growth capacity (RGC) conditions. The number of white long lateral roots produced during RGC tests correlated significantly with the number of white long lateral roots under lathhouse conditions. Increased mitotic activity is required for root elongation. However, mitotic frequencies could not be used to assess RGC because of the confounding effects of independent growth cycles in individual roots. Cell expansion and transformation of insoluble carbohydrates are important controls of root elongation. The relationship between root and shoot growth under RGC conditions may not support the role of shoot elongation in decreasing root elongation. Conversely, this may indicate that RGC tests alter the endogenous controls of root and shoot growth.


1984 ◽  
Vol 60 (6) ◽  
pp. 335-339 ◽  
Author(s):  
David G. Simpson

The antitranspirants, XEF-4-3561-A. Wilt Pruf, Plantgard, Folicote, Clear Spray, and Vapor Gard, were sprayed on container-grown lodgepole pine, white spruce, western hemlock, and Douglas-fir seedlings before or after a 12-week cold (+ 2 °C) storage period. The effects of the six antitranspirants on root growth capacity, storability, and field performance varied between species. XEF-4-3561-A. Wilt Pruf, Folicote, and Vapor Gard increased moisture stress avoidance of all species, while Plantgard and Clear Spray had no effect. None of the six antitranspirants are recommended for use on white spruce, western hemlock, or Douglas-fir planting stock because of the risk of reducing field performance. Further trials of XEF-4-3561-A and Wilt Pruf on lodgepolo pine seedlings seem War-ranted.


2009 ◽  
Vol 39 (10) ◽  
pp. 1821-1834 ◽  
Author(s):  
B. J. Hawkins ◽  
M. Stoehr

Thirty-two full-sib families of coastal Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii) with a range of predicted breeding values were monitored for growth rate, phenology, and cold hardiness over 2 years on two sites to investigate if other traits are being selected when family selection is based on height. Significant differences among families existed in most phenological, growth, and cold-hardiness traits. On average, taller families burst bud later but did not have significantly different growth rates or length of growing period than other families. We found no significant correlations between family date of bud burst and cold hardiness in late spring or between duration of shoot growth or height and autumn freezing damage. Family differences in freezing tolerance were greatest in September and October. In these months, family current-year leaf nitrogen was positively correlated with cold hardiness. Families that were most hardy in the autumn were not the most hardy families in spring. We conclude that, for the studied breeding series, selection based on height does not have a significant impact on cold hardiness. We found no consistent relationships between phenological, growth, or cold-hardiness parameters and final height that could explain family ranking by height. Relationships between grandparent elevation and dates of bud burst and cold hardiness were observed.


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