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1.
Damage to containerized forest seedlings due to freezing can occur in the fall or early winter in Canadian forest nurseries. The following spring, damage to shoots and impairment of growth is observed. The objectives of this experiment were to measure the impact of late fall low temperatures (0° to --30°C) on whole seedlings of the three most common species used for reforestation in Quebec: black spruce (BS), white spruce (WS) and jack pine (JP). Impacts of freezing temperatures on (i) whole seedling and apical bud mortality, (ii) shoot growth and root mortality, (iii) stem electrical resistance, (iv) shoot and root water relations, (v) concentrations of N, P, K, Ca, Mg, and total sugars in shoots were assessed. JP showed the highest rate of whole seedling mortality while WS showed the highest rate of apical bud mortality. JP was the most severely affected: destruction of the root system at low temperatures as well as a reduction of shoot growth and stem diameter and a decrease (more negative) in shoot and root water potential. WS showed a reduction of shoot growth despite no apparent damage to the root system at low temperatures. BS was not affected by temperatures as low as --30°C. Nutrient and sugar concentrations were not affected by low temperature treatments. 相似文献
2.
Roots of 2-year-old black spruce seedlings (Picea mariana [Mill.] B.S.P.) were exposed to freezing temperatures to destroy 20, 40, 60, and 80% of the root systems. For comparison, other root systems were pruned to eliminate the same proportions of roots. Treated and control seedlings were planted in spring 1992 at Forêt Montmorency (the Université Laval forest research station, 50 km north of Quebec City). From 1992 to 1995, survival, shoot height and stem diameter were measured. Mortality mainly occurred in 1993, the year after planting; pruned seedlings showed practically no mortality while seedlings with 20, 40, 60, and 80% of their root systems affected by frost showed mortality rates of 0, 6, 17, and 24%, respectively. Shoot height and stem diameter decreased with increasing root damage when compared to controls. After three years on the planting site, shoot height was reduced by 2, 8, 11, and 18% while stem diameter was reduced by 4, 21, 25, and 24% for 20, 40, 60, and 80% frost damage, respectively. For pruned seedlings, shoot height was increased by 3% at 20% damage and was decreased by 1, 3, and 13% for 40, 60, and 80% root damage while stem diameter was reduced by 1, 4, 8, 19% for 20, 40, 60, and 80% respectively. Use of damaged seedlings on the planting sites should be limited in order to reduce the cost of replacement planting. 相似文献
3.
When spring frosts occur on recently planted forest sites, severe damage may occur to the seedlings. The aim of the present study was to test how different low levels of nutrient concentrations in Norway spruce (Picea abies (L.) Karst.) seedlings affected spring frost hardiness and time of bud break. Seedlings were grown in a greenhouse for one season and supplied with fertiliser containing 22, 43 and 72 mg N l–1, respectively. The treatments resulted in needle nitrogen concentrations ranging from 0.9 to 1.8% in autumn. After winter storage at 0 °C, bud break was recorded on seedlings growing in the greenhouse, outdoors and in growth chambers at 12 °C and at 17 °C. Freezing tests were performed on seedlings directly removed from winter storage and following one week growth in the greenhouse. Seedlings receiving fertiliser with 43 mg N l–1 had less freezing injury than the two other fertilisation treatments in the present study. The earliest bud break occurred in seedlings receiving 72 mg N l–1. 相似文献
4.
Cold hardened, dehardened, and newly flushed foliage of one year old white spruce (Picea glauca [Moench.] Voss) seedlings were exposed to various sub-zero temperatures (--2 to --22.5°C) either in the dark or light. The freezing treatment had no significant effect on the variable fluorescence to maximal fluorescence ratio (Fv/Fm) of hardened seedlings, either in the light or dark. Also, no visible damage or increase in electrolyte leakage were evident in either the light or the dark treated seedlings. Both dehardened and newly flushed foliage were significantly affected by the freezing treatment, and light enhanced the effect. A decline in Fv/Fmincreased electrolyte leakage and visible damage were observed at warmer temperatures in newly flushed needles than in dehardened needles. Seedlings exposed to sub-zero treatments in the light also had lower Fv/Fm, increased electrolyte leakage and showed more visible damage than seedlings exposed to the same sub-zero treatments in the dark. The temperature where 50% of the needles were damaged (LT50) as estimated from visible damage data was --10.8°C in the light and --12.1°C in the dark for dehardened, one year old needles. The LT50in newly flushed needles was --4.8°C in the light and --6.2°C in the dark. Recovery of Fv/Fmvalues 3 days after freezing exposure was only evident in treatments where little visible damage was present. Both Fv/Fmand electrolyte leakage were strongly correlated with visible damage. 相似文献
5.
Ethane production was evaluated as a method for assessing freeze damage to loblolly pine (Pinus taeda L.) seedlings by comparing it to the widely used electrolyte leakage method. Paired measurements, first ethane production and then electrolyte leakage, were conducted on the pooled needle samples at temperatures between 0° and –12°C. Ethane production rates increased in a linear fashion with decreasing temperatures between 0° and –12°C for both Virginia Coastal Plain (R2=0.80) and Marion County, Florida (R2=0.87) seed sources. The Florida seedlings were consistently 2° to 4°C higher than the Virginia seedlings at a given ethane level. Electrolyte leakage expressed as Index of Injury initially increased with decreasing temperatures, but then leveled off at or decreased below –8°C. The log-log linear regression of ethane production against Index of Injury indicated good correspondence for both seed sources (Virginia – R2=0.81; Florida – R2=0.91). Ethane production appears more rapid and to require less sampling than does electrolyte leakage while producing comparable results to the electrolyte leakage method. 相似文献
6.
《Scandinavian Journal of Forest Research》2012,27(2):137-147
Abstract This study examined the impact of increased irrigation efficiency on the hardening and frost tolerance of 2-year-old containerized white spruce seedlings in the context of groundwater protection, irrigation management and the maintenance of seedling quality in northern climates. The seedlings were grown under three different irrigation regimes (IR =30%, 40% and 55% v/v; cm3 H2O/cm3 substrate) and were hardened under conditions of natural photoperiod and temperature. After being subjected to artificial frost tests on four sampling dates during autumn, the seedlings were compared for bud development and frost tolerance. IR had no influence on frost tolerance as determined by measurements of physiological (electrolyte leakage, root water loss) and morphological (shoot damage, root initiation) variables. At the end of the second growing season, there was no significant difference between IRs in seedling height, root collar diameter, shoot dry mass and root dry mass. The results indicate that the amount of water applied to large-dimension 2-year-old white spruce seedlings during the growing season can be significantly decreased without prematurely impeding their growth or hindering their acquisition of frost tolerance. 相似文献
7.
Five week old white spruce [Picea glauca (Moench) Voss] seedlings were placed within controlled-temperature growth chambers, and subjected to one of four periodic, chilling treatments for approximately 16 weeks. The treatments differed in the frequency of 24 hour exposure to 5 °C the seedlings received, and ranged from no chilling (control), to once every two, three or four days. After 25 weeks of growth, the control seedlings were significantly taller than all chilling-exposed seedlings, but stem diameters were similar. Chilling did not affect either needle length or needle density compared to control seedlings. During a water deficit test, frequently chilling-exposed seedlings maintained significantly higher mid-day shoot water potentials under extreme water stress. Re-watering after the drought resulted in all chilling-treated seedlings recovering faster to pre-stress shoot water potential levels than the control seedlings. Measurements of new root growth after 21 days at 10 °C indicated that previous chilling exposure delayed or inhibited new root production. 相似文献
8.
Fine root electrolyte leakage and moisture content: indices of Sitka spruce and Douglas-fir seedling performance after desiccation 总被引：1，自引：0，他引：1
In spring 1992, 2-year-old bare-rooted seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were exposed for 0, 0.5, 1.0, 1.5, or 3 h in a controlled environment room at 20°C. Plants were desiccated in batches during February and March; 100 seedlings of each species were planted in 5 20-plant plots at each of 6 planting sites using the normal planting times and methods of each area. The effect of exposure was assessed within 24 h of desiccation on a subsample of plants by measuring fine root moisture content and electrolyte leakage and, in a limited number of cases, needle water potential. These measures were related to survival and growth after the first and second growing seasons.There were significant interactions between the effect of desiccation and site. The measurements following desiccation were significantly related to survival and growth on some but not all sites; in general, the effect of condition was more pronounced on sites with low spring rainfall than on sites with greater than 100 mm rainfall per month during the spring of planting. Root electrolyte leakage was significantly related to performance in slightly more cases than needle water potential or root moisture content. 相似文献
9.
Chlorophyll fluorescence as an indicator of frost hardiness in white spruce seedlings from different latitudes 总被引：3，自引：0，他引：3
This study examined the utility of variable chlorophyll fluorescence (Fvar) to detect freezing damage in white spruce seedlings of four seedlots. Logistic regression analysis done for freezing tests in September showed that visible needle damage from freezing could be estimated by the Fvar attributes Fo/IABS(r2=0.94), Fp(r2=0.98), Fv/Fm (r2=0.99), and F1(r2=0.86). The regression curves indicated that for all four fluorescence attributes, inflection points occurred between 10 and 20% visible needle damage. The lack of a relationship between fluorescence attributes and visible seedling needle damage in October through December is because the minimum temperature (–18 and –24°C respectively) applied was insufficient to cause needle damage. Freezing-induced changes to Fvar attributes can be detected which also result in photosynthetic rate decreases when no visible needle damage, and even electrolyte conductivity changes are evident. Fvar attribute differences due to freezing can be resolved to the seedlot level. The Fvar curve feature manifested 5 seconds after dark-adapted seedlings have been exposed to light (F5s) will estimate (r2=0.76) photosynthetic rate after freezing. 相似文献
10.
Assessment of Root Freezing Damage of Two-year-old White Spruce,Black Spruce and Jack Pine Seedlings
《Scandinavian Journal of Forest Research》2012,27(3):343-353
Whole root systems of 2-yr-old containerized white spruce [Picea glauca (Moench) Voss], black spruce [Picea mariana (Mill.) B.S.P.] and jack pine (Pinus banksiana Lamb.) seedlings, with intact root plugs, were exposed to various frost temperatures, which a preliminary test indicated would induce approximately 0 (control), 20, 40, 60, 80 and nearly 100% frost damage. Damage to root systems was evaluated using: (1) two measures of electrolyte leakage (relative conductivity and total tissue leakage after autoclaving); (2) water loss after pressurization; (3) chlorophyll fluorescence (Fv/Fm, maximal PSII photochemical efficiency) measured 4, 21 and 30 days after the beginning of seedling regrowth and (4) live root dry mass measured 21 days after the artificial frost and 60 days after the beginning of regrowth. Seedling survival and growth after the artificial frost were evaluated using live root dry mass measured after 60 days of regrowth and new shoot length, stem diameter, and root and shoot dry mass. Live root dry mass, dead tissue leakage, jack pine root water loss and fluorescence measurements were all significantly correlated with one or more of the growth variables and the number of significant correlations varied with species. Dead tissue leakage measurements appear to be the most promising method for evaluating root damage to 2-yr-old well-developed root systems of these species. 相似文献
11.
Current-year needles of Sitka spruce (Picea sitchensis) can be injured by frost after hardening of stem and buds in the autumn, and in Scotland trees of southern provenances are most susceptible to damage. In October 1993 a frost of −5°C caused needle damage to clonal plants of Alaskan, Queen Charlotte Islands, and Washington provenances of Sitka spruce that had been selected for variation in the onset of root dormancy. Visual damage assessment revealed significant differences among clones in the severity of damage, and this damage was positively correlated with the lateness of root dormancy. Measurement of electrolyte leakage from shoot samples confirmed the observed differences between clones. The large clonal differences in frost hardiness found in this study demonstrate a potential for selecting frost tolerant trees from within southern provenances of Sitka spruce. 相似文献
12.
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. 相似文献
13.
Gary A. Ritchie 《New Forests》1986,1(1):29-42
An experiment was conducted to ascertain what relationships might exist among dormancy status, cold hardiness and stress resistance in 2+0 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), seedlings. Seedlings were lifted from a western Washington nursery on six dates spanning the 1980–81 lifting season. On each date samples of seedlings were subjected to the following treatment: (1) tumbling for 5 minutes, (2) desiccation of roots for 30 minutes at 30°C and 2.1 kPa vapor pressure deficit, (3) exposure of shoots to temperatures of –10°C, –15°C or –20°C for two hours and (4) unstressed control. On two lift dates sub-samples of seedlings were placed into –1°C storage and held for two months before the above stress treatments were administered. Bud dormancy status was determined, using a bud break test, on seedlings from each lift date before and after storage.After one growing season in the field percent survival, vigor, height growth and shoot and root weight were determined on stressed and unstressed seedlings. Survival and vigor were less affected by the stress treatments than were height and weight. Severity of stress was in the order –20°C > –15°C > desiccation > handling > –10°C. Degree of cold injury was directly related to seedling dormancy status whether dormancy status had been attained in the nursery from natural chilling or in frozen storage. Seedlings in a mid-range of dormancy release (between deep rest and quiescence) were most resistant to all imposed stresses. 相似文献
14.
《Forest Ecology and Management》1987,18(4):299-318
Bare-root jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) seedlings were planted on a boreal cut-over site and subsequent growth and seedling water relation patterns were monitored over the first growing season. Comparison of morphological development between white spruce and jack pine showed jack pine seedlings had greater new root development and a lower new shoot/new root ratio, while white spruce seedlings had greater new shoot development. Seasonal water relation patterns showed white spruce seedlings to have a greater decrease in xylem pressure potential (x) per unit increase in transpirational flux density in comparison to jack pine seedlings. These results suggest that the greater resistance to water flow through the soil-plant-atmosphere continuum in white spruce seedlings compared to jack pine seedlings may be due to the relative lack of new root development in white spruce. Stomatal response of the seedlings showed that as absolute humidity deficit between the needles and air (AHD) increased, needle conductance (gwv) decreased in both species, but at low AHD levels white spruce had gwv approximately 35% higher than jack pine. For white spruce seedlings, gwv decreased as x became more negative in a predictable curvilinear manner, while gwv of jack pine seedlings responded to x with a threshold closure phenomenon at approximately - 1.75 MPa. Tissue water potential components for jack pine and white spruce seedlings at the beginning and end of the growing season showed jack pine to reach turgor loss at 76% relative water content while white spruce reached turgor loss at 88% relative water content. White spruce seedlings showed osmotic adjustment over the growing season, with an osmotic potential at turgor loss of - 1.27 MPa and - 1.92 MPa at the beginning and end of the growing season, respectively. Jack pine did not show any osmotic adjustment over the growing season. The implication of morphological development on water relation patterns are discussed with reference to successful seedling establishment. 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(1-4):32-36
Frost hardiness of tissues along the length of the stem and the root was investigated in first‐year black spruce (Picea mariana (Mill.) B.S.P.) seedlings. Frost hardiness of 1 cm long stem and root segments was evaluated based on Index of Injury, calculated from post‐freezing electrolyte leakage. Frost hardiness was tested approximately weekly beginning seven weeks after seedlings were transferred from an 18 to a 10 h photoperiod, both at day/night temperatures of 26°C/16°C. Trees were transferred to temperatures of 10°C day and 5°C night at a 10 h photoperiod after a further 18 days. Frost hardiness was greater at the terminal bud and least at the root tips. Although shoots were generally more frost hardy than roots, differences in hardiness along the stem and root axes were gradual, rather than abruptly differing at the shoot‐root interface. All tissues, including root tips, increased in frost hardiness after conditioning for 18 days under short photoperiods (10 h) and warm temperatures (26?C/16°C, day/night). Under cold temperatures (10°C/5°C, day/night) all tissues, excepting the root tips, tolerated — 16°C with little subsequent electrolyte leakage. 相似文献
16.
A field trial was conducted investigating the single season growth response of 1+0 313 PSB Engelmann spruce (Picea engelmannii Parry ex Engelm.) and lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings planted into two different soil thermal regimes at three high-elevation locations spanning 200 km in the Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zone in the Cariboo Mountains of central British Columbia. Temperature treatments represented the extremes of soil temperature commonly found in high-elevation clear-cuts. A warm soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 18 to 25 °C at –10 cm) consisting of a bare mineral soil hummock (average dimensions of 100 cm × 100 cm × 40 cm) was contrasted with a cool soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 10 to 13 °C at –10 cm) comprised of organic forest floor overlying mineral soil. By the end of the growing season, seedlings of both species planted into the warm treatment generally exhibited greater root, stem, foliage, and total seedling biomass than cool treatment seedlings. Measurements of root growth at 30, 60, and 90 days after planting showed that total root number and total root length were consistently greater for warm treatment seedlings than for cool treatment seedlings. Root growth was greater from the bottom rather than from the side of the root plug for all seedlings. These results suggest that the effect of low soil temperatures on outplanted styroblock conifer seedlings is pronounced and may be limiting growth performance in high-elevation plantations in British Columbia. We recommend silvicultural treatments that secure natural regeneration, ensure that warmer microsites are always planted, and utilize seedling stocktypes able to make rapid lateral root growth into warmer surface organic horizons. 相似文献
17.
The relationship between physiological status and theability to withstand the stresses of lifting, coldstoring and planting was evaluated from 1992–1995 inSitka spruce (Picea sitchensis (Bong.) Carr.)2 + 1 transplants of Washington/northern Oregon originsgrowing in Ireland. Needle primordium initiationcontinued until later and cold hardiness developedmore slowly in the mild lifting season of 1994/95. The seasonal decline in shoot mitotic activity wasgenerally similar each year, with apices becominginactive in December. Cell divisions in roots ceasedin November or December. Shoots began to deharden inearly February each year, but the rates of dehardeningwere slow until March. Cell divisions in root apicesresumed in February each year, compared with March forshoot apices. The vitality of the seedlings followingcold storage was high for most lift dates except theOctober and April dates. The period of highest stressresistance (as indicated by cold hardiness levels) forlifting for immediate planting was from about lateNovember/early December to early March; shoots werecold hardy to about –20 °C (LT50) at thistime. Seedlings could be lifted and cold stored (1–2 °C)until May/June when shoots were cold hardyto about –30 °C or lower, which coincided withthe period from mid- to late December until March. 相似文献
18.
Yellow birch seedlings (Betula alleghaniensis Britt.) that had lost more than 90% of their stem hydraulic conductivity during ambient winter temperatures were exposed to 0 and 20 days of a simulated winter thaw followed by a 48-h freezing treatment at 0, -5, -10, -20 and -30 degrees C. After measuring freezing injury to shoots and roots, the seedlings were placed in a greenhouse where recovery of xylem conductivity and new growth were measured. Shoot xylem cavitation was measured as percent loss of hydraulic conductivity. Shoot freezing injury was assessed by electrolyte leakage (EL) and root freezing injury was assessed by EL and triphenyl tetrazolium chloride reduction. Seedlings pretreated with thaw had higher stem water contents and suffered more freezing damage to roots and shoots (at -20 and -30 degrees C, respectively) than unthawed seedlings. After 3 weeks in a greenhouse, seedlings from the 0, -5 and -10 degrees C freezing treatments showed complete recovery of xylem conductivity, with substantially increased stem water contents. Poor recovery of hydraulic conductivity was observed only in seedlings that were subjected to freezing treatments at -20 and -30 degrees C, regardless of thaw treatment. Of these embolized seedlings, however, only those not previously thawed showed recovery of hydraulic conductivity or regained stem water content after 9 weeks in the greenhouse. Shoot dieback, bud burst and length of new shoots were significantly related to the extent of stem xylem cavitation and freezing injury. We conclude that (1) the simulated winter thaw predisposed yellow birch seedlings to freezing damage in shoots and roots by dehardening tissues and increasing their water content; (2) root freezing damage in turn affected the seedlings' ability to refill embolized stem xylem, resulting in considerable residual xylem embolism after spring refilling; (3) further recovery of stem xylem conductivity was attributable to growth of new vessels; (4) and the permanent residual embolism, together with root and shoot freezing injury, caused increased dieback, bud mortality and reduced growth of new shoots. 相似文献
19.
The effect of warm storage (15°C) for 0, 15 or 31 days, applied after cold storage until April, and date of lifting to cold
storage on the physiological condition and field performance of two-year-old oak seedlings (Quercus robur L.) was investigated. Assessments before planting included plant moisture status, root and shoot dry weight, root growth
potential (RGP), while after planting root growth, shoot growth phenology, shoot and root dry matter accumulation and stem
quality were assessed. Warm storage effects were large, but lift date effects were small. Warm storage for 31 days reduced
height and diameter growth, stem quality, total biomass, root growth, and reduced stem quality in the field, but 15 days storage
had a smaller effect. Warm storage delayed bud break and shoot growth cessation but survival was unaffected. The depletion
of food reserves during storage and low moisture availability might have caused shoot dieback leading to the development of
poor quality stems. There was evidence that dry weight fraction of both the shoot tip and the taproot provided good information
on the quality of the stock before planting. RGP was also a good indicator of quality. Electrolyte leakage readings from fine
and taproots were not reliable indicators of plant quality. 相似文献
20.
Bigras FJ 《Tree physiology》2000,20(18):1227-1234
To assess the responses and plasticity of white spruce seedlings (Picea glauca (Moench) Voss) to high temperatures, 12 open-pollinated families differing in growth performance were exposed to a 30-min heat treatment of 42, 44, 46, 48, or 50 degrees C with or without heat preconditioning at 38 degrees C for 5 h. Damage was evaluated based on chlorophyll fluorescence parameters after heat preconditioning, after the heat treatments and during a 7-day recovery period. Visible needle damage was also evaluated after the heat treatments and 14 days later. Chlorophyll fluorescence parameters indicated that seedlings subjected to a heat treatment of 42-43 degrees C lost the ability to phosphorylate and donate water to photosystem II (PSII). A heat treatment of 44-46 degrees C severely limited the ability of the seedlings to use NADPH and ATP in the Calvin cycle. Based on visible needle damage, families with superior height-growth performance were more sensitive to heat stress than families with intermediate or inferior height-growth performance. Moreover, families with superior height-growth performance had low photochemical efficiencies in the light (DeltaF/F(m)') after heat treatment. Heat preconditioning increased the thermotolerance of the seedlings. However, the data suggest that white spruce seedlings exhibiting fast-growing characteristics under present conditions may not grow as well at higher temperatures. 相似文献