Black Spruce Seedlings Research Articles

Acquired thermotolerance of jack pine, white spruce and black spruce seedlings.

The acquired thermotolerance of first-year seedlings of jack pine (Pinus banksiana Lamb.) hardened at 36, 38, 40 or 42 degrees C for 90, 180 or 360 minutes and of black spruce (Picea mariana (Mill.) B.S.P.) hardened at 34, 36, 38 or 40 degrees C for 30, 90, 180 or 360 minutes was determined by comparison of needle damage to that of non-hardened seedlings (25 degrees C) following exposure to temperatures of 49 and 47.5 degrees C, respectively. Compared to seedlings kept at 25 degrees C, heat injury sustained from exposure to high temperatures was markedly reduced following hardening for 180 minutes at 36 and 38 degrees C in jack pine and black spruce, respectively. Increasing the exposure time at 36 degrees C in jack pine, and at 36 to 40 degrees C in black spruce, also reduced needle damage. The duration of increased thermotolerance was investigated in jack pine, black spruce and white spruce (Picea glauca (Moench) Voss) by comparing heat injury from high temperatures in non-hardened seedlings and in seedlings hardened at 38 degrees C for 180 minutes a day for either 1, 3 or 6 days. In all three species, the duration of acquired thermotolerance increased with the number of days of heat hardening. For jack pine and white spruce seedlings hardened at 38 degrees C for 6 days, increased thermotolerance persisted for at least 14 and 10 days, respectively, after the end of the hardening treatment. In contrast, the thermotolerance of black spruce seedlings hardened at 38 degrees C for 6 days remained elevated for only 4 days.

Influence of near-ultraviolet light enhancement and photosynthetic photon flux density during photoperiod extension on the morphology and lignin content of black spruce seedlings

When containerized black spruce seedlings (Picea mariana (Mill.) B.S.P.) are grown rapidly in greenhouse culture, they sometimes bend over, grow horizontally and become deformed. This phenomenon has been known to affect between 5% and 10% of a winter greenhouse crop. In this study, near-ultraviolet lamps were used to supplement the artificial light received from high-pressure sodium lamps and the effects on seedling morphology and lignin contents were examined. Neither height to diameter ratios nor lignin concentrations were significantly affected by UV radiation flux density. However, seedling biomass, height, root collar diameter, lignin content, and lignin to cellulose ratios of stems were significantly correlated with total photosynthetic photon flux density (PPFD) received during photoperiod extension. Height to diameter ratios were negatively correlated with PPFD during photoperiod enhancement because of a greater relative increase in diameter growth compared with height growth. Neither UV nor PAR flux density affected the percentage of black spruce seedlings having stem deformations greater than 30 ° from the vertical.

Evaluation of morphological attributes as response variables to perennial competition for 4-year-old black spruce and jack pine seedlings

The sensitivity of seedling morphological attributes to changing competition levels was evaluated on 4-year-old black spruce (Piceamariana (Mill.) B.S.P.) and jack pine (Pinusbanksiana Lamb.) seedlings to determine the most appropriate response variables to be used in the assessment of early plantation performance. A total of 720 seedlings (360 per species) were sampled between 1987 and 1989, covering a range of stock types, soil textures, and competition levels. A competition index, derived from hemispherical photographs, provided an estimate of incident radiation received by each sampled seedling. Seedling stem volume at time of planting was used as a covariate in the regression analyses. Stratification by plantation was done to account for variations in site quality. The results from this study demonstrated that total height or current height increment were not reliable for quantifying individual seedling response to inter specific competition for 4-year-old black spruce or jack pine plantations. Overall, the most consistent response variable was total seedling dry weight. Coefficients of determination ranged from 0.116 to 0.534 for black spruce and from 0.601 to 0.810 for jack pine across the range of sites and stock types. If it is inappropriate to determine total seedling dry weight, root collar diameter would be the best substitute. Correlation coefficients between these two variables were 0.897 for black spruce and 0.912 for jack pine.

Accumulation of free amino acids in the shoots and roots of three northern conifers during drought.

The effects of drought on the free amino acid pools in 21- to 23-week-old seedlings of black spruce (Picea mariana (Mill.) Britt.), white spruce (Picea glauca (Moench.) Voss) and jack pine (Pinus banksiana Lamb.) were followed during soil drying. Although water and pressure potentials were sensitive to water deficits, large changes in osmotic potential were not recorded until after the development of severe drought. Total soluble amino nitrogen in the shoots and roots of the three species rose as turgor declined, with peak concentrations attained late in the drought period when the pressure potentials of the shoots approached zero. All white spruce seedlings were alive at zero turgor and showed large decrements in osmotic potential, but concentrations of free amino nitrogen in the roots and shoots showed only modest increases, reaching 125 to 150% of their control values. In contrast, large numbers of black spruce and jack pine were dead or severely damaged at zero turgor, and only small changes in osmotic potential were detected during soil drying. Nevertheless, concentrations of soluble amino nitrogen in both species reached 150 to 200% of control values a few days before the seedlings died. Alanine, arginine, aspartic acid/asparagine, glutamic acid/glutamine, glycine, hydroxyproline and proline were the major components of the free amino acid pools under both water-stressed and non-stressed conditions, with the largest and most consistent increases observed in the roots of all three conifers. Although proline was an important and dynamic component of the free pools, absolute concentrations were commony equalled or exceeded by other free amino acids in the roots and shoots and nearly always exceeded by the concentration of aspartic acid/asparagine in both tissues. Differences in drought resistance among the three conifers were not reflected by unique patterns of amino acid accumulation or by large differences in absolute concentrations of the free amino acid pools.

Atmospheric CO2 enrichment and the development of frost hardiness in containerized black spruce seedlings

The hypothesis that a relatively brief exposure to elevated atmospheric CO2 could increase the frost resistance of shoots was tested on containerized black spruce seedlings (Piceamariana (Mill.) B.S.P.). Seedlings were exposed to 1000 ppm CO2 toward the end of their second growing season in an unheated production tunnel and in a heated greenhouse. In 1987, continuous 10-week CO2 exposures were applied in conjunction with mineral nutrient fertilization, and freezing tests were conducted each week. In 1988, a series of shorter 2-week CO2 exposures was applied to different groups of seedlings and no mineral nutrients were added. Controlled freezing tests were conducted at −10 °C and were followed by electrolytic conductivity measurements to assess frost injury. Under all experimental conditions, freezing tests on seedlings from both the production tunnel and the greenhouse indicated significantly greater frost damage for the CO2-enriched seedlings than for the controls. Late-growing season CO2 enrichment negatively affected the bud initiation – bud development stage of frost-hardiness development.

Costs of Growing Containerized Seedlings Using Different Schedules at Kingsclear, New Brunswick

Abstract This study examines the relative costs of producing containerized black spruce seedlings under four production schedules, two of which are hypothetical. Using actual expenditure data for a three-crop per year schedule, the production costs for three, two-crop schedules (winter sowing dates of January 1, February 1, and March 1), were derived to examine the cost differences of postponing the sowing date of the winter crop. Average annual costs per thousand seedlings were at least $22 higher under a two-crop compared to a three-crop schedule. Among the two-crop schedules, a winter crop sowing on March 1st yielded the lowest overall cost, although annual savings were no more than $1 per thousand. This minimal difference reflects the high cost of heating greenhouses in the winter, even when empty. North. J. Appl. For. 7:73-76, June 1990.

Survey and ecological aspects of presumed ectomycorrhizal fungi associated with black spruce in northern Minnesota

Twenty-two stands of black spruce, Picea mariana (Mill.) B.S.P., in northern Minnesota were surveyed for ectomycorrhizal fungi. Site selection criteria in black spruce stands included geologic history, soil type, stand origin, age, and productivity. Site preference relationships were noted for several of the 46 species of fungi collected during the 2-year study. Twenty-five isolates were tested in aseptic culture for their ability to form ectomycorrhizae with black spruce seedlings. Ectomycorrhizae were produced by Cenococcum sp., Laccaria bicolor (Maire) Orton, Laccaria laccata var. moelleri Singer, Rhizopogon sp., and Suillus cavipes (Opat.) Smith & Thiers.

White and black spruce seedling development using the concept of relative addition rate

Ingestad's concept of relative addition rate was used to grow a range of seedling types, of both black (Picea mariana) (Mill.) B.S.P.), and white spruce (Picea glauca (Moench) Voss). Seedlings were grown for about 18 weeks in styrofoam containers under greenhouse conditions, and fertilized at exponentially increasing rates of either one, two, four or six per cent per day, following a one month pretreatment period. Pretreatment consisted of applying a nutrient solution proportionally low in nitrogen, but that had a relatively high conductivity compared to the initial solutions used in the exponentially increasing fertilizer treatments. Black spruce seedlings grew fastest, had significantly more root development or had a higher efficiency of nitrogen uptake when nutrients were applied at exponentially increasing amounts. In contrast, white spruce grew more rapidly when fertilized with a constant level of fertilizer (control treatment). Biomass allocation and nitrogen concentrations in seedlings of both spec...

Somatic embryogenesis and plantlet regeneration from cultured shoots and cotyledons of seedlings from stored seeds of black and white sprees (Picea Mariana and Picea glauca)

Embryogenic callus was induced from cultured explants of 12- to 30-day seedlings germinated from 10- and 4-year stored seeds of black and white spruce, respectively. Plantlets were regenerated from a 12-day black spruce seedling derived embryogenic callus. This is the oldest conifer seedling material shown to give rise to embryogenic callus, and the first demonstration in spruce that seedling-derived embryogenic calli are competent of plantlet regeneration. The effect of a cytokinin pretreatment on embryogenic callus induction from 12-day black spruce seedling shoot explants was investigated. Although an induction frequency of 18% occurred after 2 weeks preculture of shoot explants on medium containing 4.5 μM benzyladenine, the cytokinin pretreatment was not significantly superior to controls given no pretreatment (12%). Age of explant influenced embryogenic induction frequencies from black and white spruce. Explants from 21-day black spruce seedlings produced embryogenic calli at a frequency of 5%. In comparison, shoot explants from 12- and 30-day white spruce seedlings given no benzyladenine pretreatment displayed induction frequencies of 38 and 18%, respectively.

Postfire black spruce establishment in subarctic and boreal Quebec

Forest regeneration in areas burned during the 1950s in northern Quebec was studied along topographic and climatic gradients, from the northern Boreal Forest to the northern Forest–Tundra. Regenerated plant communities are mostly dominated by Cladinamitis in well-drained uplands and by hygrophilous shrub species in moister lowlands. The age structure of 23 stands, as they were immediately before and about 30 years after the 1950s fires, was used to analyze the patterns of establishment and development of black spruce (Piceamariana (Mill.) B.S.P.) populations associated with fire disturbance. Postfire black spruce establishment was active during the first 20 years of vegetation recovery, then it decreased rapidly. Three older populations originating from 1936 and 1922 fires showed a rapid postfire tree establishment, whereas a long delay of recolonization was observed in the 1906 fire. Along the topographical gradient, postfire regeneration was more rapid in hill sites, whereas spruce recruitment was more abundant in lowland sites. Along a northward latitudinal gradient, prefire populations showed an increasing trend in age range, mean age, and mean age of youngest individuals. This gradient coincided also with an increasing fire rotation period from south to north. The proportion of stunted individuals in postfire populations was often more important than in prefire populations on the same sites, suggesting more rigorous growth conditions associated with forest removal. Because most black spruce seedling establishment is occurring during a short period in this area, it is suggested that stand density is determined by regeneration conditions, including seed input and seedbed quality, soon after the fire. Therefore, comparisons between prefire and 30-year-old postfire populations can be used as an index to evaluate fire impact on stand density.

Effect of straw residues on black spruce seedling growth and mineral nutrition, under greenhouse conditions

The potential allelopathic (phytotoxic or beneficial) effect of barley, oat, and wheat straw mulches was evaluated on growth, mineral nutrition, and mycorrhizal status of black spruce seedlings, under greenhouse conditions. The various straws did not affect spruce seedling height growth over a 2-month growth period. The newly formed fine roots of treated and control seedlings were mycorrhizal. Oat and wheat straw significantly enhanced foliar phosphorus content, as compared with the control. All treatments significantly depressed foliar manganese content, indicating that the straws could exert a detrimental effect on manganese uptake. Therefore, it is suggested that monitoring the status of manganese in planted spruce seedlings when using allelopathic cover straw mulches be used as a method for preventing the establishment of weed species.

Pathogenicity and attraction to host extracts of Canadian pinewood nematodes: studies with Scots pine, western larch, and black spruce seedlings

Two isolates of the pinewood nematode, Bursaphelenchusxylophilus (Steiner and Buhrer), from Canada (an r form from Ontario and an m form from Quebec) and one from Japan (an r form) were inoculated into Scots pine, Pinussylvestris L., western larch, Larixoccidentalis Nutt., and black spruce, Piceamariana (Mill.) B.S.P. to determine the pathogenicity of this nematode and to observe changes in its numbers as well as the effect it had on seedling water and tannin content. Attractiveness of water, ethyl ether, and ethyl acetate stem extracts of these conifers to the pinewood nematode was also determined. The r form of the pinewood nematode was pathogenic on all three conifers: the Japanese isolate killed more Scots pine and the Ontario isolate, more black spruce. The Quebec isolate was as pathogenic as the other two isolates to western larch, weakly pathogenic to black spruce, and nonpathogenic to Scots pine. In general, there was a positive relationship between nematode population buildup and seedling mortality. No clear relationship was found between the water content of seedling stems and changes in nematode populations. Tannin content of stems increased following inoculation with pinewood nematode, but whereas correlation values between tannin content and nematode numbers were positive and significant, they were small. Although all three isolates were attracted to all host extracts, regardless of solvent used, ethyl acetate extracts were generally more attractive. The Japanese and Ontario isolates, which originated from pines, showed no particular affinity for Scots pine extracts; however, the Ontario isolate, which was especially attracted to black spruce extracts, was also most pathogenic to black spruce.

Influence of short-term atmospheric CO2 enrichment on growth, allocation patterns, and biochemistry of black spruce seedlings at different stages of development

Black spruce seedlings (Piceamariana Mill.) were exposed to either elevated (1000 ppm) or ambient (340 ppm) atmospheric CO2 levels at different stages of seedling development over a winter greenhouse production cycle. Seedlings germinated in early February and were placed in CO2 chambers for either 3 or 6 weeks during March, April, May, or August. Total seedling biomass increased under high CO2 conditions for the March, April, and May stages of development, but showed no significant response in August. The greater part of the CO2 response occurred during the second 3 weeks of exposure in March and April but during the first 3 weeks of exposure in May. In September, those seedlings exposed to CO2 in April and May had 30 and 14%, respectively, greater biomass than control seedlings, but seedlings from the other stages of development no longer had significant differences remaining from the CO2 treatment. This suggests that it could be very efficient to give a short well-timed CO2 pulse at the beginning of the production cycle in hopes of producing a size difference that is maintained throughout the remainder of the greenhouse production cycle under ambient levels of CO2. Short-term exposure to elevated CO2 also increased the ratio of shoot dry weight to total height for the March, April, and May stages of development. The ratio of total nonstructural carbohydrates to free amino acids was negatively correlated (r2 = 0.98) with the allocation of new growth between shoots and roots as measured by the allocation coefficient, k (milligrams shoot growth per milligrams root growth). As seedlings developed along their seasonal growth cycle, ratios of total nonstructural carbohydrates to free amino acids increased and the values for k decreased. The effect of CO2 enrichment on these two factors is discussed. Monitoring total nonstructural carbohydrate and free amino acid concentrations in foliage could have potential as a method to predict the percentage of carbon allocated to root systems of entire forest stands as well as of individual tree seedlings.

Ectomycorrhizal colonization on black spruce and jack pine seedlings outplanted in reforestation sites

Six-week-old, mycorrhiza-free, bareroot jack pine and black spruce seedlings were outplanted in ten reforestation sites, situated between 45–48° latitude N and 69–74° longitude W, within the province of Quebec, representing diverse operational forestry disturbances and ecological conditions.

Water uptake by black spruce seedlings from rooting media (solution, sand, peat) treated with inorganic and oxalated aluminum

Experiments with solution cultures revealed that 1-yr-old black spruce (Picea mariana [Mill.]) seedlings growing in nutrient solutions experienced reductions in water uptake and moist plant weight when treated with water-soluble inorganic Al at the time of rapid shoot elongation. These reductions occurred with solution concentrations for Al at ≥ 16 mg L−1. Wilting was noticed with Al ≥ 8 mg L−1. In contrast, oxalated Al treatments had no visible effects on either water uptake or moist plant weight during shoot elongation. Later, near the time of budset, neither inorganic nor oxalated Al had an effect on moist plant weight or water uptake. This suggests that black spruce seedlings may or may not be susceptible to water-soluble inorganic Al depending on the degree of Al complexation afforded by the rooting medium, and by the plant roots at different times of the growing season. Water uptake was affected by the type of rooting medium in which the seedlings grew. For example, water uptake from peat was greater than water uptake from solution. Water uptake from sand was intermediate. Water uptake from solution-only cultures was probably affected by restricted O2 supply.

Root hydraulic conductivity and root growth capacity of black spruce (Picea mariana) seedlings.

The relationship between root elongation and root hydraulic conductivity was investigated in 1-year-old, overwintered black spruce (Picea mariana (Mill.) seedlings. Hydraulic conductivity was estimated by observing water flux through decapitated roots under positive pressure. Five hydraulic conductivity parameters were estimated: (1) water flux under a minimal pressure of 0.2 MPa (J(v, min)); (2) pressure at which a linear relationship between water flux and pressure began (P(min)); (3) slope of the linear water flux-pressure relationship (L(v)); (4) pressure at which the linear relationship between water flux and pressure ended (P(max)); and (5) maximum water flux (J(v, max)). Between day 1 and day 2 after thawing of the growing medium, there were significant increases in L(v) and J(v, max) but there was little, if any, root elongation. Root elongation averaged 5.4 cm seedling(-1) 5 days after thawing and 88.2 cm seedling(-1) 20 days after thawing. Root hydraulic conductivity increased with new root length initially. But between days 20 and 30, when new root length nearly doubled, P(min) was the only measure of hydraulic conductivity that increased significantly. There were significant correlations (P < 0.05) between white root length and both J(v, min) (r(2) = 0.90) and J(v, max) (r(2) = 0.91).

AL uptake by black spruce seedlings: Persistence of organic acids in al treated rooting cultures

Experiments were conducted to monitor the pH and the persistence of simple organic acids (oxalic, citric, malic, glycolic acid) with and without Al complexation in rooting cultures (sand, peat, solution-only) under non-sterile conditions, and to characterize pertinent short-term responses of black spruce seedlings (Picea mariana [Mill.]) to subsequent changes in the rooting solutions. It was shown that the organic acids decayed within about five days unless the cultures were treated with a decay-controlling fungicide such as Captan, an antoxidant containing N-(trichloromethylthio)-4-cyclohexene-12-dicarboximide. Aluminum complexation did not increase the persistence of the organic acids except for oxalic acid. In all cases, the decay of the organic acids (or of the equivalent carboxylates) led to a simultaneous increase of solution pH which was most pronounced in the non-buffered solution cultures without Al. Captan did not affect the growth of black spruce seedlings, but was lethal to yellow birch (Betula alleghaniensis Britton) seedlings. The pH of tissuemized roots taken from the black spruce seedlings following treatments with oxalate and citrate (within and without Al) reflected the change of pH within the culture solutions.

The influence of night temperature under declining photoperiod on bud initiation in black spruce seedlings

The effect of night temperature on the speed of bud initiation in black spruce (Piceamariana (Mill.) B.S.P.) container seedlings was studied. Day lengths were progressively shortened in plant growth chambers to simulate the natural day-length decline that occurs in the fall at latitude 48°N. During the period of day-length decline a constant 26 °C day temperature was maintained, while night temperatures of 5, 7.5, 10, 14, 18, 22, 24, or 26 °C were imposed. When the night temperature was 10–24 °C, first signs of bud initiation were observed in 12–15 days, while 100% bud initiation was attained in 15–22 days. When the night temperature was 5, 7.5, or 26 °C, first bud initiation was observed in 15–22 days, while 100% bud initiation was not attained until 40 days.

Container Volume Affects Survival and Growth of White Spruce, Black Spruce, and Jack Pine Seedlings: A Literature Review

Abstract This paper is the first general review of the affects of container volume on the survival and growth of containerized white spruce, black spruce, and jack pine seedlings. The review shows that the literature on this topic is fragmentary and inconsistent. Seedling growth in the greenhouse production phase has been more completely quantified than subsequent establishment and growth after out-planting in the field. In the greenhouse production phase, seedling growth increased from 72 to 360% when the container volume was tripled in size. After outplanting in the field, seedling growth trends were more variable. Seedling height growth increased from 34 to 84% when container volume was tripled in size. Seedling survival was more difficult to assess because of limited data. Only white spruce showed a 10% increase in survival with an increase in container volume. The indications from this literature review suggest that nursery managers and practicing foresters should become more aware of the limitations imposed on seedling survival and growth due to container volume. To maintain optional survival and growth for white spruce, black spruce and jack pine, the container volume should range from 90 to 120 cm3. North. J. Appl. For. 5:185-189, Sept. 1988.

Heat tolerance of actively growing, bud-initiated, and dormant black spruce seedlings

To determine the effect of stage of bud development on heat tolerance, overwintered black spruce seedlings (Piceamariana (Mill.) B.S.P.) were (i) maintained in a dormant state, (ii) allowed to grow new shoots under favorable greenhouse conditions, or (iii) induced to initiate bud scales using short-photoperiod treatment following a period of new shoot elongation. Seedlings of the three shoot types were then exposed for 10 min to temperatures of 25, 42, 45, 50, or 55 °C in an environmental test chamber. Damage to the current-year shoot was lower in bud-initiated seedlings than in active seedlings, particularly at 42 °C, when 0 and 46%, respectively, of the length of the main shoot was damaged. The current-year shoot growth was much more sensitive to heat stress than the lignified first-year shoot, and therefore dormant seedlings, which had only first-year shoot growth, were most heat tolerant, showing damage only at 50 and 55 °C.