The response of Norway spruce seedlings to simulated acid mist

Four pot experiments are reported in which Norway spruce ( Picea abies (L.) Karst) seedlings, of different nutrient status, were treated with acid mist for one growing season in open-top chambers (OTCs). Combinations of H⁺, SO₄²⁻, NH₄⁺ and NO₃⁻ were applied at different frequencies of application and supplying different doses of S and N kg ha⁻¹. Plant growth, visible injury, frost hardiness and nutrient status were observed. These experiments were undertaken to improve our understanding of the interaction of environmental factors such as nutrition and mist-exposure frequency on seedling response to N and S deposition.
Both acidity (pH 2·7) and SO₄²⁻ ions were necessary to induce visible injury. Mist containing SO₄²⁻, H⁺ and to a lesser extent NH₄⁺ significantly reduced winter frost hardiness. Increasing the misting frequency, and to a lesser extent the overall dose, increased the likelihood of acid mist causing visible injury and reducing frost hardiness. Post-planting stress, low N status and needle juvenility increased the likelihood of acid mist causing visible injury. Increased plant vitality, adequate N status and growth rate reduced the likelihood of acid-mist-induced reductions in frost hardiness.
Principles underlying the responses of spruce seedlings treated in controlled conditions to acid mist are discussed.     

Effect of frost nights and day and night temperature during dormancy induction on frost hardiness, tolerance to cold storage and bud burst in seedlings of Norway spruce

For trees, the ability to obtain and maintain sufficient levels of frost hardiness in late autumn, winter and spring is crucial. We report that temperatures during dormancy induction influence bud set, frost hardiness, tolerance to cold storage, timing of bud burst and spring frost hardiness in seedlings of Norway spruce (Picea abies (L.) Karst.). Bud set occurred later in 12°C than in 21°C, and later in cool nights (7°C) than in constant temperature. One weekly frost night (−2.5°C) improved frost hardiness. Cool nights reduced frost hardiness early, but improved hardiness later during cold acclimation. Buds and stems were slightly hardier in 21°C than in 12°C, while needles were clearly hardier in 12°C. Cold daytime temperature, cool nights and one weekly frost night improved cold storability (0.7°C). Seedlings receiving high daytime temperatures burst buds later, and were less injured by light frost some days after bud burst.     

Predicting spring frost sensitivity by bud development and temperature sum in Norway spruce seedlings

Nurseries would benefit greatly if frost hardiness (FH) of seedlings could be predicted by some environmental variable or by bud development in spring. We investigated the FH of 1-year-old Norway spruce (Picea abies (L.) Karst.) seedlings of local origin. The seedlings were stored frozen until incubated in the growth chamber at six different temperature sums (TSs) (0, 55, 88, 142, 185 and 240 d.d., >5°C) from mid-February to mid-March. FH of the buds, stems and previous year needles was assessed on three occasions. When the TS was 88 d.d. or less, buds exhibited only microscopic signs of development, even when seedlings tolerated temperatures below −10°C. As TS increased, primordial needles and primordial stems of buds grew while FH weakened, especially in previous year needles. When the TS was at least 142 d.d., all plant parts were frost hardy to approximately −6°C. Monitoring TS and bud development can help predict FH of Norway spruce seedlings in spring. However, more studies with seedlings of different ages and from multiple locations are necessary to appreciate the generality of our results.     

Does ice crystal formation in buds explain growth disturbances in boron-deficient Norway spruce?

Loss of apical dominance in boron-deficient trees has been suggested to be due to frost damage of terminal buds and leaders. Excessive nitrogen (N) supply can exacerbate boron (B) deficiency by the dilution-effect. N may also have direct effects on winter hardiness. We studied frost hardening of buds of Norway spruce (Picea abies L. Karst.) in healthy-looking trees and in trees with growth disturbances. The effect of B and N on frost hardiness was studied in a factorial fertilisation experiment during cold acclimation. Frost hardiness was determined by differential temperature analysis (DTA) and scoring of visual damage. In a DTA profile of apical buds with a piece of stem, low-temperature exotherm (LTE) predicted bud injury, while two of the observed high-temperature exotherms and two of the observed intermediate-temperature exotherms were non injurious. Appearance of LTE followed changes in air temperature. The risk of frost damage was not affected by fertilisation treatments or previously observed growth disturbances. However, when the bud structure was deformed by severe B deficiency, the supercooling ability disappeared. Such buds are probably killed by freezing in nature and therefore, frost damage may play a secondary role in the development of growth disturbances.     

Differences in frost hardiness of two Norway spruce morphotypes growing at Mt. Brocken, Germany

Norway spruce (Picea abies (L.) Karst.) exhibits strong ecotypic variation along altitudinal gradients in morphological traits, e.g. slenderness of crowns or arrangement of second-order branches. We were interested whether montane and lowland morphotypes differ in a key trait for the survival in cold environments, i.e. frost hardiness, and asked: (i) are montane morphotypes more resistant to frost damage and (ii) do they have a lower risk of frost damage by late frosts in spring than lowland morphotypes?We used the electrolyte leakage-method to measure frost hardiness on a monthly basis from October 2006 to May 2007 in stands of the montane and lowland morphotypes at Mt. Brocken in the Harz Mountains, Germany.LT₅₀ (i.e. the temperature that results in 50% of maximum electrolyte leakage) was assessed by freezing treatments in a frost chamber and was significantly influenced by morphotype, month and minimum ambient temperatures. LT₅₀ was significantly lower in the montane than in the lowland morphotype, with −107 °C and −49 °C, respectively. However, the interactions between morphotype with minimum ambient temperature or month were not significant. Thus, as frost hardiness of the two morphotypes responded to temperature in the same way, both morphotypes can be supposed to be exposed to the same risk of frost damage during hardening in autumn and dehardening in spring.     

Enhanced ethylene emissions from red and norway spruce exposed to acidic mists

Acidic cloudwater is believed to cause needle injury and to decrease winter hardiness in conifers. During simulations of these adverse conditions, rates of ethylene emissions from and levels of 1-aminocyclopropane-1-carboxylic acid (ACC) in both red and Norway spruce needles increased as a result of treatment with acidic mists but amounts of 1-malonyl(amino)cyclopropane-1-carboxylic acid remained unchanged. However, release of significant quantities of ethylene by another mechanism independent of ACC was also detected from brown needles. Application of exogenous plant growth regulators such as auxin, kinetin, abscisic acid and gibberellic acid (each 0.1 millimolar) had no obvious effects on the rates of basal or stress ethylene production from Norway spruce needles. The kinetics of ethylene formation by acidic mist-stressed needles suggest that there is no active inhibitive mechanism in spruce to prevent stress ethylene being released once ACC has been formed.     

Effect of thawing time, cooling rate and boron nutrition on freezing point of the primordial shoot in norway spruce buds

BACKGROUND: Effects of cooling rates on bud frost hardiness have been studied but there is little information on bud responses to thawing. Since the cell wall pore size has been found to increase with boron (B) deficiency, B deficiency may affect the supercooling ability of buds in winter. METHODS: The effects of duration of thawing time and rate of cooling on bud frost hardiness of Norway spruce (Picea abies) were studied in a B fertilization trial in February 2003 and March 2005. Frost hardiness of apical buds was determined by differential thermal analysis (DTA) and visual scoring of damage. KEY RESULTS: In 2003, the freezing point of primordial shoots of buds (T(f)), i.e. the low-temperature exotherm (LTE), was, on average, -39 degrees C when buds were thawed for less than 3 h and the T(f) increased to -21 degrees C after 18 h of thawing. During the first 4 h of thawing, the rate of dehardening was 6 degrees C h(-1). In 2005, buds dehardened linearly from -39 degrees C to -35 degrees C at a rate of 0.7 degrees C h(-1). In 2003, different cooling rates of 1-5 degrees C h(-1) had a minor effect on T(f) but in 2005 with slow cooling rates T(f) decreased. In both samplings, at cooling rates of 2 and 1 degrees C h(-1), T(f) was slightly higher in B-fertilized than in non-fertilized trees. By contrast, at very short thawing times in 2003, T(f) was somewhat lower in B-fertilized trees. CONCLUSIONS: There was little evidence of reduced frost hardiness in trees with low B status. This study showed that buds deharden rapidly when exposed to above-freezing temperatures in winter, but if cooled again they reharden more slowly. According to this study, rapid dehardening of buds has to be taken into account in assessments of frost hardiness.     

Changes in cold hardiness of introduced and native interior Alaskan evergreens in relation to water and lipid content during spring dehardening

Needle hardiness of introduced yellow pine, Pinus banksiana Lamb., lodgepole pine, P. contorta Dougl, and native white spruce, Picea glauca (Moench) Voss, were assessed by the effective prefreezing temperature method. Yellow pine needles were less hardy than lodgepole pine or white spruce needles in Alaska on each date measured. Although hardiness decreased in springtime in all species, decreases in hardiness in yellow pine began before temperatures were above ?20°C, apparently in response to day length, while decreases in hardiness in lodgepole pine and white spruce began only when mean temperatures were above 0°C. Hardiness was increased by decreasing the water content of yellow pine and spruce needles. However, only the latter increased its field hardiness by decreased water contents, and only to a small degree. Large decreases in phospholipid occurred during the dehardening period, indicating the presence of major membrane-associated changes. However, changes in hardiness did not closely parallel those in phospholipid; hardiness decreased before phospholipid did in spruce and after phospholipid did in lodgepole pine. In yellow pine, changes in hardiness were more closely related to changes in phospholipid content. Decreases in phospholipid appeared to be correlated with the day length in all species.     

The relation between growth cessation and frost hardening in Scots pines of different origins

The cessation of shoot elongation, diameter growth and needle elongation were compared with the initiation of frost hardening of the stems and needles in an 8-year-old provenance trial of Scots pine (Pinus sylvestris L.) established in central Finland. The saplings were of six different origins ranging from Estonia to northern Finland, forming a latitudinal gradient of ca. 10°N. The frost hardiness of the stems of current-year shoots was assessed by electrical impedance analysis and that of current-year needles by electrolyte leakage and visual scoring of damage. Artificial freezing tests were used in the assessments. The pattern of growth cessation (shoot and needle elongation, diameter growth) tended to follow the latitude of origin, i.e. growth ceased in the northernmost provenance first and in the southernmost one last. Both stems and needles of the northern provenances hardened earlier than the southern ones, but the differences in hardiness disappeared as hardening progressed. Growth cessation and initial hardening to -15°C were clearly correlated at the provenance level, indicating that growth must cease prior to hardening, and that earlier cessation of growth predicts earlier frost hardening of stems and needles. No differences in frost hardiness of stems were found at the provenance level at the end of the growing period in August. At that time, the frost hardiness of needles of the northernmost provenance was higher than that of other origins. Within the provenance, the stems were less hardy than the needles.     

The effects of long-term elevation of air temperature and CO on the frost hardiness of Scots pine

The frost hardiness of 20 to 25-year-old Scots pine (Pinus sylvestris L.) saplings was followed for 2 years in an experiment that attempted to simulate the predicted climatic conditions of the future, i.e. increased atmospheric CO₂ concentration and/or elevated air temperature. Frost hardiness was determined by an electrolyte leakage method and visual damage scoring on needles. Elevated temperatures caused needles to harden later and deharden earlier than the controls. In the first year, elevated CO₂ enhanced hardening at elevated temperatures, but this effect disappeared the next year. Dehardening was hastened by elevating CO₂ in both springs. The frost hardiness was high (相似文献   

Assessing frost hardiness of Pinus bungeana shoots and needles by electrical impedance spectroscopy with and without freezing tests

Aims Nursery and forest operations require that frost hardiness results be produced faster than can be provided by controlled freezing tests. There is a great challenge to develop a rapid method for predicting frost hardiness that might not necessitate controlled freezing tests. The aim of this study was to examine the assessment of the frost hardiness of shoots and needles of Pinus bungeana by electrical impedance spectroscopy (EIS) with and without controlled exposure to freezing.Methods The frost hardiness of current-year shoots and needles of P. bungeana in an 8-year-old provenance field trial was measured at Shisanlin Nursery in Beijing, China, from September 2006 to January 2007 by means of EIS and conventional electrolyte leakage (EL). In the same plants, but without controlled freezing test, were monitored the EIS parameters in current-year shoots and needles.Important findings The results showed that (i) after controlled freezing tests, the frost hardiness estimated by EIS parameters (extracellular resistance, r e, and membrane time constant, τ m) was significantly correlated with the frost hardiness assessed by EL method (r = 0.95) and (ii) for the samples not exposed to controlled freezing treatment, the relaxation time τ 1 for shoots and β for needles had greater correlations with the frost hardiness estimated by EL after controlled freezing tests relative to the other parameters (r = ?0.90 for shoots and r = 0.84 for needles, respectively). The parameters r e of shoots and needles and τ m of needles might be applied for measuring frost hardiness of samples after exposed to controlled freezing tests. The frost hardiness results can be obtained within 48 h. The parameters τ 1 of shoots and β of needles could be used for estimating the frost hardiness of samples without using a controlled freezing test. The frost hardiness results can be obtained within 24 h.     

Interactions between green spruce aphid (Elatobium abietinum (Walker)) and Norway and Sitka spruce under high and low nutrient conditions

1 Green spruce aphid (Elatobium abietinum) is a serious pest of spruce (Picea spp.) in north‐west Europe, causing defoliation of one‐year‐old and older needles. 2 Relationships between population development of E. abietinum, needle loss and tree growth were compared for five pure genotypes of Sitka spruce and mixed‐genotype material of Sitka and Norway spruce, grown under high and low nutrient conditions. 3 Despite wide differences in flushing date between spruce genotypes, E. abietinum populations peaked on the same date on each genotype and on the mixed‐genotype material, irrespective of nutrient supply. 4 Larger aphid populations developed on trees grown under high nutrient conditions than under low nutrients. However, more needles were lost per aphid in the low nutrient treatment and overall defoliation rates in the two nutrient treatments were similar. 5 Total aphid numbers differed significantly between Sitka spruce genotypes within nutrient treatments, but not in relation to bud‐burst or needle terpene content. Reductions in height growth caused by infestation were greater (15–44%), and related to mean aphid densities and defoliation, in the low nutrient treatment, but were smaller (11–27%) and not related to aphid density and defoliation in the high nutrient treatment. 6 Development of E. abietinum populations was similar on Norway and Sitka spruce, but Norway spruce lost fewer needles. However, the effects of infestation on tree growth were more closely related to aphid density and were similar for Norway and Sitka spruce. 7 Infestation caused a decrease in total root dry weight of Norway and Sitka spruce in proportion to the reductions observed in above‐ground growth.     

The effect of previously infested spruce needles on the growth of the green spruce aphid, Elatobium abietinum, and the effect of the aphid on the amino acid balance of the host plant

The effect of chlorosis induced in needles of Sitka and Norway spruce by the green spruce aphid on growth of the aphid is investigated, and the effect of infestation of the aphid on amino acid levels in Sitka spruce foliage is reported. On both Sitka and Norway spruce green spruce aphids were heavier when reared on chlorotic (previously infested) needles than when reared on green (previously uninfested) needles. The effect was more pronounced on Sitka than on Norway spruce. Infestation of the aphid altered the amino acid balance of Sitka spruce foliage but not the concentration of total amino acids. Possible causes of chlorosis, the influence of individual amino acids on aphid growth, the potential effect of chlorosis on outbreaks of the aphid and the differences in susceptibility of Sitka and Norway spruce to damage by the aphid are discussed.     

Phenolic compounds in Norway spruce as affected by boron nutrition at the end of the growing season

The increase in concentrations of phenolic compounds in boron (B) deficiency has been demonstrated in many herbaceous plant species, but information on woody plants is scarce. It has been suggested that accumulation of phenolic compounds plays a role in the development of cold hardiness in herbaceous plants but also that B deficiency decreases winter hardiness. Here we study the effects of B nutrition on phenolic compounds in Norway spruce (Picea abies L.) in the course of cold acclimation. Phenolic compounds were analysed in Norway spruce seedlings from three different B-fertilisation treatments in two harvests: non-acclimated and cold-acclimated seedlings. Norway spruce phenolic compounds consisted mainly of condensed tannins. During B deficiency, condensed tannins and monocoumaroyl–astragalin der. 1 increased in non-acclimated seedlings. The increase in tannins was 21%, which was nearly significant. However, the effect of B on phenolic compounds was almost absent in cold-acclimated seedlings. The condensed tannin concentration increased much more with time in the simulated autumn than due to B deficiency, and we conclude that the B effect was probably not large enough to be important for the hardening of the seedlings. The total phenolic concentrations more than doubled during the course of cold hardening suggesting that phenolics have a role in the winter hardiness in Norway spruce.     

Seasonal Fluctuations of Ascorbate-Related Enzymes: Acute and Delayed Effects of Late Frost in Spring on Antioxidative Systems in Needles of Norway Spruce (Picea abies L.)

Seasonal changes of ascorbate peroxidase and monodehydroascorbateradical reductase activities were studied in foliar tissuesof Norway spruce (Picea abies L.). In mature needles, APX activitiesdid not show seasonal fluctuations and were similar to thosefound in resting buds. Monodehydroascorbate radical reductaseactivity was higher in needles than in buds and higher in winterthan in summer. Maximum activities of both enzymes were foundbefore bud break and minimum activities in newly formed needles.When spruce seedlings were exposed to an artifical frost eventof –5°C for one night in spring, ascorbate peroxidaseactivity declined in young needles before the onset of visibleinjury but corresponding to a sudden upsurge in lipid peroxidation.After one week, some shoots showed severe symptoms of injury,some were slightly injured and others did not show any visibleinjury. In lethally injured needles, antioxidative protection(ascorbate peroxidase, monodehydroascorbate radical reductase,glutathione reductase, glutathione, ascorbate, superoxide dismutase)had collapsed. Surviving needles showed a coordinated increasein all components of the antioxidative system suggesting anefficient induction of defense systems. However, enhanced protectionwas observed only transiently. In fall, needles that had beenexposed to frost in spring contained significantly less antioxidantsthan unstressed needles indicating that unseasonal frost causedmemory effects. (Received September 16, 1995; Accepted May 28, 1996)     

The Influence of Photoperiod and Temperature on the Development of Frost Hardiness in Seedlings of Pinus silvestris and Picea abies

The influence of short days and low temperature on the development of frost hardiness in seedlings of Scots pine (Pinus silvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown for 6 months in glasshouses and climate chambers, was investigated. The degree of hardiness was estimated by freezing the shoots of the seedlings to predetermined temperatures. After 8 weeks in a glasshouse the viability of the seedlings was determined by establishing bud flushing. The most effective climate for the development of frost hardiness was short days (SD) and low temperature (2°C); the next most effective was SD and room temperature (20°C). However, long days (LD) and low temperature also had a marked effect on the development of hardiness. A combination of 3 weeks’treatment with SD and 20°C, and 3 weeks with SD and 2°C gave the same results as 6 weeks with SD and 2°C. The results clearly demonstrate the importance of the photoperiod prior to low temperature for the development of frost hardiness. In conclusion both short days and low temperature induce frost hardiness development. Probably this occurs by initiation of different processes in the two cases. The degree of frost hardiness development appears to depend on the sum of these different processes and on the timing between them.     

The effect of soil temperature on the bud phenology, chlorophyll fluorescence, carbohydrate content and cold hardiness of Norway spruce seedlings

The effects of soil temperature on the shoot phenology, carbohydrate dynamics, chlorophyll fluorescence and cold hardiness of 4-year-old Norway spruce seedlings ( Picea abies L. Karst.) were studied. The experiment was carried out under controlled conditions in the Joensuu dasotrons. Air conditions were similar but soil temperatures differed by treatments (9, 13, 18 and 21°C) during the second growing period in the dasotrons. The after-effects of the treatments were investigated during the third growing period following the treatments. Low soil temperature increased the starch content of needles and delayed the loss of starch at the end of the growing season. The photochemical efficiency ( F _v/ F _m) of the PSII of the current-year needles was reduced at the lowest soil temperature. The cold hardiness of needles correlated with the soluble sugar content. The differences in soil temperature had no effect on the timing of bud burst. No after-effects from the treatments were observed during the third growing period in the dasotrons.     

Daylength and temperature during seed production interactively affect adaptive performance of Picea abies progenies

Adaptive traits in Picea abies (Norway spruce) progenies are influenced by the maternal temperatures during seed production. Here, we have extended these studies by testing the effects of maternal photoperiod and temperature on phenology and frost hardiness on progenies. Using eight phytotron rooms, seeds from three unrelated crosses were made in an environmental 2 x 2 factorial combination of long and short days and high and low temperatures. The progenies were then forced to cease growth rapidly at the end of the first growing season. An interactive memory effect was expressed the second growth season. Progenies from high temperature and short days, and from low temperatures and long days, started growth later in spring, ceased shoot growth later in summer, grew taller and were less frost hardy in the autumn than their full siblings from low temperatures and short days, and from high temperatures and long days. Norway spruce has developed a memory mechanism, regulating adaptive plasticity by photoperiod and temperature, which could counteract harmful effects of a rapidly changing climate.     

Seasonal fluctuation of dehydrins is related to osmotic status in Scots pine needles

Seasonal variation in dehydrins and other soluble proteins of Scots pine (Pinus sylvestris L.) needles, buds and bark were analyzed monthly for 1 year from 1998 to 1999. Dehydrin-related proteins of 60 and 56 kDa were identified immunologically in all tissues. The concentration of the 60-kDa dehydrin was highest during the winter (October-February) in buds and bark but increased in early spring (March-May) in needles. Accumulation of the 60-kDa dehydrin in the needles in springtime was related to the decreasing osmotic potentials of the needles. The 56-kDa dehydrin was present only during the growing season, as was a 50-kDa dehydrin, which only appeared in bud and bark tissues. The soluble protein concentration of needles did not differ significantly between seasons, but in bark and bud tissues the protein concentrations were at their lowest level in newly grown tissues (June-August). The level of several polypeptides was higher during the winter-spring period than in the growing season, especially in bark and bud tissues. These proteins may be related to cold hardiness or dormancy in overwintering Scots pine. Dehydrin-related proteins in needles are linked to springtime changes in the osmotic status of needles rather than to their cold acclimation.     

Relationship between respiratory depletion of sugars and loss of cold hardiness in coniferous seedlings over-wintering at raised temperatures: indications of different sensitivities of spruce and pine

Long-term effects of elevated winter temperatures on cold hardiness were investigated for Norway spruce (Picea abies L. Karst.), lodgepole pine (Pinus contorta Dougl.) and Scots pine (Pinus sylvestris L.). Two-year-old seedlings with the same pre-history of growth and cold hardening in the field were maintained from early December to late March at two field sites in northern Sweden and in a cold room. The temperatures at these locations averaged –13·5, –8·9 and 5·5°C, respectively. Following treatments, carbohydrate contents and cold tolerances were assessed. Needle respiration was also analysed during the 5·5°C treatment. Cold tolerance of lodgepole pine and Scots pine was much reduced following the 5·5°C treatment. Cold tolerance was somewhat reduced in lodgepole pine following the –8·9 °C treatment, but was essentially maintained in spruce throughout all treatments. The cold tolerance of needles was strongly correlated with their soluble sugar contents. Spruce maintained cold hardiness by having larger reserves of sugars and lower rates of respiration which decreased more rapidly as sugars were depleted. Tolerance of lodgepole pine to frost desiccation was also much reduced following the 5·5°C treatment.