Scots Pine Seedlings Research Articles

Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth.

Heatwaves combined with drought affect tree functioning with as yet undetermined legacy effects on carbon (C) and nitrogen (N) allocation. We continuously monitored shoot and root gas exchange, δ13 CO2 of respiration and stem growth in well-watered and drought-treated Pinus sylvestris (Scots pine) seedlings exposed to increasing daytime temperatures (max. 42°C) and evaporative demand. Following stress release, we used 13 CO2 canopy pulse-labeling, supplemented by soil-applied 15 N, to determine allocation to plant compartments, respiration and soil microbial biomass (SMB) over 2.5 wk. Previously heat-treated seedlings rapidly translocated 13 C along the long-distance transport path, to root respiration (Rroot ; 7.1 h) and SMB (3 d). Furthermore, 13 C accumulated in branch cellulose, suggesting secondary growth enhancement. However, in recovering drought-heat seedlings, the mean residence time of 13 C in needles increased, whereas C translocation to Rroot was delayed (13.8 h) and 13 C incorporated into starch rather than cellulose. Concurrently, we observed stress-induced low N uptake and aboveground allocation. C and N allocation during early recovery were affected by stress type and impact. Although C uptake increased quickly in both treatments, drought-heat in combination reduced the above-belowground coupling and starch accumulated in leaves at the expense of growth. Accordingly, C allocation during recovery depends on phloem translocation capacity.

Effects of overstory tree density, site preparation, and ground vegetation on natural Scots pine seedling emergence and survival in northern boreal pine forests

Natural regeneration is a commonly used forest regeneration method in northern Finland. It is not known, however, what would be the optimal overstory density and ground vegetation composition for seedling emergence and survival, and if site preparation is needed to accompany overstory density manipulation. We studied the effects of overstory density (unthinned control and thinning to 50, 150, and 250 trees·ha−1) and ground vegetation removal (mechanical site preparation with disc trenching) on the number of naturally germinated pine seedlings and survival of individual seedlings over a period of 8 to 11 years. Bare mineral soil was a superior seedbed compared to intact vegetation cover, even though the mortality rate was high on mineral soil. Greater cover of lingonberry, crowberry, and slash had a negative effect on seedling number. Seedling mortality was initially high (60% died during the first 2 years) but decreased throughout the first 5 years. The survival rate of seedlings located in the mineral soil of the upper part of the disc trencher track was twice as high as that of seedlings located in the lower part of the track. High coverage of hair mosses (Polytrichum spp.) was associated with poorer seedling survival. An overstory density of 50–150 trees·ha−1 with site preparation seems to be an efficient treatment to promote regeneration under these circumstances.

Diverging responses of water and carbon relations during and after heat and hot drought stress in Pinus sylvestris.

Forests are increasingly affected by heatwaves, often co-occurring with drought, with consequences for water and carbon (C) cycling. However, our ability to project tree resilience to more intense hot droughts remains limited. Here, we used single tree chambers (n = 18) to investigate transpiration (E), net assimilation (Anet), root respiration (Rroot) and stem diameter change in Scots pine seedlings in a control treatment and during gradually intensifying heat or drought-heat stress (max. 42 °C), including recovery. Alongside this, we assessed indicators of stress impacts and recovery capacities.In the heat treatment, excessive leaf heating was mitigated via increased E, while under drought-heat, E ceased and leaf temperatures reached 46 °C. However, leaf electrolyte leakage was negligible, while light-adapted quantum yield of photosystem II (F′v/F′m) declined alongside Anet moderately in heat, but strongly in drought-heat seedlings, in which respiration exceeded C uptake. Drought-heat largely affected the hydraulic system as apparent in stem diameter shrinkage, declining relative needle water content (RWCNeedle) and water potential (ΨNeedle) reaching −2.7 MPa, alongside a 90% decline of leaf hydraulic conductance (KLeaf).Heat alone resulted in low functional impairment and all measured parameters recovered quickly. Contrary, following drought-heat, the recovery of KLeaf was incomplete and stem hydraulic conductivity (KS) was 25% lower than the control. However, F′v/F′m recovered and the tree net C balance reached control values 2 days post-stress, with stem increment rates accelerating during the second recovery week. This indicates a new equilibrium of C uptake and release in drought-heat seedlings independent of hydraulic impairment, which may slowly contribute to the repair of damaged tissues. In summary, Scots pine recovered rapidly following moderate heat stress, while combined with drought, hydraulic and thermal stress intensified, resulting in functional damage and slow recovery of hydraulic conductance. This incomplete hydraulic recovery could critically limit evaporative cooling capacities and C uptake under repeated heatwaves.

Selective herbicides to control Sosnowsky’s hogweed (Heracleum sosnowskyi Manden.) in pine and spruce plantations

In recent years, in the European part of Russia, massive and extremely negative distribution of Sosnovsky’s hogweed (Heracleum sosnowskyi Manden.) on various land categories has been observed. On the lands of the forest fund, there is also a threat of a rapid spread of hogweed, mainly in low-density stands, open spaces, forest plantations, and in fresh clearings. As a result, the growth of woody plants, first of all conifers, is suppressed, their death is observed, and environmental, aesthetic and industrial damage increases. Mechanical measures to combat hogweed are not effective enough and are very laborious. The article presents the results of a field experiment carried out in the Leningrad region in 2019–2020. The aim of the study was to assess the effectiveness of herbicides towards Sosnovsky’s hogweed and accompanying herbaceous species, as well as to evaluate their selectivity towards seedlings of Scots pine (Pinus sylvestris L.) and spruce (Picea abies (L.) Karst.). The herbicides studied were Anchor-85, Mortyra, Deimos, Lontrel-300 and Magnum in various combinations and application rates. The herbicides Anchor-85, Mortyra and Magnum showed high efficiency in suppressing Sosnovsky’s hogweed, however, only Anchor-85 and Mortyra turned out to be selective enough in relation to conifers.

The results of the use of gridless technology for the selection and sowing in a forest nursery of 1000 pieces equalized by weight and size (thickness) of Scotch pine seed fractions

The aim of our research is to analyze the quantitative composition of standard and non-standard Scots pine seedlings grown with all sowing options: calibrated small and large seeds, as well as uncalibrated seeds. As the material for the study, we used a batch of Scots pine seeds, which were divided by weight into two equal parts. Subsequently, one part was calibrated on a sieve-free separator in thickness into small and large fractions, and the second was not calibrated. The size gap in the calibrated fractions was determined experimentally based on the minimum and maximum size of the seed thickness. All the seeds obtained were sown separately from each other in the nursery areas. At the end of the second growing season, using the field method of accounting for the grown planting material, a sample of standard and non-standard seedlings was carried out. As a result, it was found that in crops with calibrated seeds of non-standard seedlings is 25 … 30% less than in crops with non-calibrated seeds. Thus, sowing with Scots pine seeds calibrated in thickness makes it possible to significantly increase the productivity of forest nursery areas in comparison with sowing with uncalibrated seeds.

Drought affects carbon partitioning into volatile organic compound biosynthesis in Scots pine needles.

The effect of drought on the interplay of processes controlling carbon partitioning into plant primary and secondary metabolisms, such as respiratory CO2 release and volatile organic compound (VOC) biosynthesis, is not fully understood. To elucidate the effect of drought on the fate of cellular C sources into VOCs vs CO2 , we conducted tracer experiments with 13 CO2 and position-specific 13 C-labelled pyruvate, a key metabolite between primary and secondary metabolisms, in Scots pine seedlings. We determined the stable carbon isotope composition of leaf exchanged CO2 and VOC. Drought reduced the emission of the sesquiterpenes α-farnesene and β-farnesene but did not affect 13 C-incorporation from 13 C-pyruvate. The labelling patterns suggest that farnesene biosynthesis partially depends on isopentenyl diphosphate crosstalk between chloroplasts and cytosol, and that drought inhibits this process. Contrary to sesquiterpenes, drought did not affect emission of isoprene, monoterpenes and some oxygenated compounds. During the day, pyruvate was used in the TCA cycle to a minor degree but was mainly consumed in pathways of secondary metabolism. Drought partly inhibited such pathways, while allocation into the TCA cycle increased. Drought caused a re-direction of pyruvate consuming pathways, which contributed to maintenance of isoprene and monoterpene production despite strongly inhibited photosynthesis. This underlines the importance of these volatiles for stress tolerance.

Long-term fate of nitrogen fixation in Pleurozium schreberi Brid (Mit.) moss carpets in boreal forests

Feather mosses and associated cyanobacteria serve as an important source of nitrogen (N) in boreal forests; however, few studies have effectively traced the N2 fixation in-situ for more than one year. The purpose of this study was to assess the long-term fate of N2 fixed in feather moss carpets in boreal forests of northern Sweden. We conducted a seven-year 15N2(g) labelling and tracing experiment in a boreal forest with a moss bottom layer dominated by Pleurozium schreberi Brid (Mitt). Mesocosms of forest floor with and without mosses present were exposed to a 10% 15N2(g) atmosphere for five days after which samples of moss, shrub, pine seedling and O horizon were taken at varied intervals and analysed for δ15N. Plots were split and burned in year seven to assess the effect of fire on liberating moss N for uptake by Scots pine (Pinus sylvestris L.) seedlings. Feather mosses treated with 15N2(g) were highly enriched in 15N one month after labelling which subsequently declined after seven years to 13% of the original 15N enrichment in green tissue. No measurable 15N enrichment was observed in shrubs or the O horizon in the presence of labelled mosses until greater than five years after the labelling experiment. Fire can liberate moss N, but we did not observe a direct effect of fire on N uptake by pine seedlings. This long-term study indicates that N2 fixed by cyanobacteria in feather moss carpets is conserved in moss tissue for extended periods and slowly transferred to the forest soil O horizon as moss tissue decomposes suggesting that moss N2 fixation is most important as an ecosystem N source at long time scales.

Survival and growth of Scots pine (Pinus sylvestris) seedlings in north Sweden: effects of planting position and arginine phosphate addition

ABSTRACT Forest regeneration by tree planting on harvested sites in the boreal forests of northern Europe is frequently preceded by site preparation to increase survival and growth of the seedlings. We studied whether a small addition of arginine phosphate (AP treatment) at the time of planting would further enhance the seedlings’ early performance. Following two growth seasons, we investigated survival and growth of Scots pine (Pinus sylvestris) seedlings on 11 locations between latitudes 61.1°N and 67.1°N in the boreal forest of northern Sweden. The planting positions of seedlings were on capped mounds and bare mineral soil following mechanical site preparation, and in non-prepared soil. We found that seedling survival following site preparation increased with AP treatment. On capped mounds, seedling survival was more variable and appeared more dependent on precipitation during the first month after planting than seedlings positioned in the mineral soil. The positive effect of AP treatment on seedling growth differed between sites and was more pronounced on sites with longer growing seasons. AP treatment had no significant effect on survival of seedlings planted in non-prepared soil, while the positive effect on growth was more pronounced at sites with higher fertility using this planting position.

Биометрические характеристики посадочного материала как тест-показатель успешности культур Pinus silvestris L.

The creation and cultivation of artificial plantations of conifers largely depends on the planting material quality. The paper is devoted to the study of the relationship between the main parameters of planting material of Scots pine (Pinus silvestris L.) with inventory indices of artificial plantations. Forest trials of Scots pine in the Arkhangelsk region, created in a haircap-moss forest site type, were investigated. Seedlings of Scots pine with standard size were divided into large, medium, small according to the diameter of the root cervix in order to set the experiment, which aimed to determine the relationship between the parameters of planting material and characteristics of the forming plantations. The research purpose determined the main task, mainly, to find out from which plants the “trees of the future” (fast-growing large specimens) are laid out. Plants grown from the large seedlings are characterized by the greatest height. This position, in relation to individuals formed from medium and small planting material, is maintained and gradually increases. From the initial phases of development, a kind of mobile equilibrium is established in the studied plantation. All the trees are growing at a very fast rate, but the initial (at the time of planting on the silvicultural area) size of the planting material corresponding to the pine plants that survived in different years on the plantations continues to remain constant. It was found that, the largest number of leaders (47 % of all survived seedlings) grew of the large seedlings by the end of the 2nd age class. Therefore, high-quality soil treatment together with the use of high-quality proportionally developed planting material significantly increases the inventory indices of plants in the stand, and allows getting the target assortments15–20 years earlier.

Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect

Exogenous application of the plant hormone methyl jasmonate (MeJA) can trigger induced plant defenses against herbivores, and has been shown to provide protection against insect herbivory in conifer seedlings. Other methods, such as mechanical damage to seedlings, can also induce plant defenses, yet few have been compared to MeJA and most studies lack subsequent herbivory feeding tests. We conducted two lab experiments to: (1) compare the efficacy of MeJA to mechanical damage treatments that could also induce seedling resistance, (2) examine if subsequent insect damage differs depending on the time since induction treatments occurred, and (3) assess if these induction methods affect plant growth. We compared Scots pine (Pinus sylvestris) seedlings sprayed with MeJA (10 or 15 mM) to seedlings subjected to four different mechanical bark damage treatments (two different bark wound sizes, needle-piercing damage, root damage) and previous pine weevil (Hylobius abietis) damage as a reference treatment. The seedlings were exposed to pine weevils 12 or 32 days after treatments (early and late exposure, hereafter), and resistance was measured as the amount of damage received by plants. At early exposure, seedlings treated with needle-piercing damage received significantly more subsequent pine weevil feeding damage than those treated with MeJA. Seedlings treated with MeJA and needle-piercing damage received 84% less and 250% more pine weevil feeding, respectively, relative to control seedlings. The other treatments did not differ statistically from control or MeJA in terms of subsequent pine weevil damage. For the late exposure group, plants in all induction treatments tended to receive less pine weevil feeding (yet this was not statistically significant) compared to control seedlings. On the other hand, MeJA significantly slowed down seedling growth relative to control and all other induction treatments. Overall, the mechanical damage treatments appeared to have no or variable effects on seedling resistance. One of the treatments, needle-piercing damage, actually increased pine weevil feeding at early exposure. These results therefore suggest that mechanical damage shows little potential as a plant protection measure to reduce feeding by a bark-chewing insect.

ПЕРЕРАБОТКА ОТХОДОВ ЛЕСОЗАГОТОВИТЕЛЬНЫХ И ДЕРЕВООБРАБАТЫВАЮЩИХ ПРЕДПРИЯТИЙ В НЕТРАДИЦИОННЫЙ МЕЛИОРАТИВНЫЙ СУБСТРАТ С ПРИМЕНЕНИЕ ЭКОЛОГИЧЕСКИ ЧИСТЫХ ТЕХНОЛОГИЙ

In Russia, in the field of rapidly and dynamically developing woodworking industry, the issue of recycling waste from logging and woodworking enterprises is becoming relevant. The article reflects information about a new devel-oped technology for processing waste from logging and woodworking enterprises. The developers have proposed an environmentally friendly technology for processing organic waste into a product that has an effective reclamation effect and increases the natural potential of soils. The technology proposed by the authors is based on the unique technical capabilities of the developed installation - a highly efficient mill that grinds down to nano-sized fineness, and a highly efficient mixer that makes it possible to obtain homogeneous mixtures of various materials and different fineness. The unconventional substrate obtained in this way, due to the scientifically grounded composition and ratios of the composite components of organic waste, has effective reclamation properties that increase the soil potential, as well as restoring the fertility of the humus horizon. The use of an unconventional ameliorative substrate in nurseries increased the survival rate and growth rates of Scots pine seedlings both in the open field and in the greenhouse. Thus, the installation proposed by the authors in one technological operation enables the processing of waste from logging and woodworking enterprises and ultimately obtain a product that helps to increase soil potential of degraded lands

The Actual Lead Toxicity for Scots Pine Seedlings in Hydroculture

The Actual Lead Toxicity for Scots Pine Seedlings in Hydroculture

Effect of Prunus serotina Ehrh. Volatile Compounds on Germination and Seedling Growth of Pinus sylvestris L.

In temperate European forests invaded by Prunus serotina Ehrh. (black cherry), a reduction in the spontaneous regeneration capacity of Pinus sylvestris L. (Scots pine) is observed. It could be caused by various factors, including allelopathic properties of this invasive plant. In this study the phytotoxic effect of P. serotina volatile compounds on P. sylvestris and the seasonal variation in this effect were assessed. Simple assays showed that volatiles emitted from P. serotina leaves significantly inhibited root growth of P. sylvestris seedlings. Their negative effect on stem growth was much weaker. The strongest phytotoxic effect on Scots pine seedlings was caused by the volatiles emitted from the youngest black cherry leaves. In fresh foliage of P. serotina, nineteen volatile organic compounds were identified by gas chromatography–mass spectrometry (GC–MS). The dominant compound was benzaldehyde. On the basis of tests of linalool alone, it was found that this monoterpene present in the volatile fraction has a strong allelopathic potential and inhibits germination, root elongation and shoot elongation of pine seedlings. The results of our research suggest that volatile compounds from P. serotina leaves could limited survival of P. sylvestris individuals in the seedling phase.

FUNGI COLONIZING CONIFEROUS SEEDLINGS IN FOREST NURSERIES OF MIDDLE SIBERIA

The study was carried out in four forest nurseries of Middle Siberia. Affected seedlings of Scots pine (Pinus sylvestris L.), Scots Siberian stone pine (Pinus sibirica Du Tour), and Siberian spruce (Picea obovata Ledeb.) were collected for molecular phytopathological examination. In total, 14 fungal taxa were identified in the needles and roots of the plants. The most dominant among them were Sydowia polyspora (Bref. Tavel) E., Didymella glomerata (Corda) Qian Chen L. Cai, Cladosporium herbarum (Pers.) Link, Lophodermium seditiosum Minter, Staley Millar, Phialocephala fortinii C. J. K. Wang H. E. Wilcox and Cadophora finlandica (C. J. K. Wang H. E. Wilcox) T. C. Harr. McNew. The richness of the fungal taxa was higher in the needles than in the roots of all the tree species studied. The obtained results could be used for implementing more effective phytosanitary measures in the studied nurseries.

Sphaeropsis sapinea and Associated Endophytes in Scots Pine: Interactions and Effect on the Host Under Variable Water Content

The ascomycete Sphaeropsis sapinea is the causal agent of the Diplodia Tip Blight disease on pines and other conifer species. This fungus has a symptomless endophytic life stage. Disease symptoms become visible when trees have been weakened by abiotic stress, usually related to warmer temperatures and drought. Currently, this disease is observed regularly in Scots pine (Pinus sylvestris) sites in parts of Europe, such as Germany, increasing dramatically in the last decade. Changes in climatic conditions will gradually increase the damage caused by this fungus, because it is favored by elevated temperature. Thus, host trees with reduced vitality due to climate change-related environmental stress are expected to be more susceptible to an outbreak of Diplodia Tip Blight disease. There is currently no established and effective method to control S. sapinea. This project aims to reveal the nature of the endophyte community of Scots pine. Utilizing the antagonistic core community of endophytes could serve as a novel tool for disease control. Results from this study provide a starting point for new solutions to improve forest health and counter S. sapinea disease outbreaks. We screened potential antagonistic endophytes against S. sapinea and infected Scots pine seedlings with the most common endophytes and S. sapinea alone and combination. The host was stressed by limiting access to water. The antagonism study revealed 13 possible fungi with the ability to inhibit the growth of S. sapinea in vitro, for example Sydowia polyspora. None of the tested co-infected fungi (Desmazierella acicola, Didymellaceae sp., Microsphaeropsis olivacea, Sydowia polyspora, and Truncatella conorum-piceae) showed strong necrosis development in vivo, even when host stress increased due to drought. However, the infection experiment demonstrated that drought conditions enhance the effect of the disease outbreak, triggering S. sapinea to cause more necrosis in the infected twigs.

Induction of Defense Responses in Pinus sylvestris Seedlings by Methyl Jasmonate and Response to Heterobasidion annosum and Lophodermium seditiosum Inoculation

The induction of defense responses in Pinus sylvestris L. seedlings by methyl jasmonate (MeJA) was investigated in three experiments. Two different MeJA application methods were tested, and induction of defense responses was assayed by seedling inoculation with Heterobasidion annosum (Fr.) Bref. and Lophodermium seditiosum Minter, Staley and Millar. In the first experiment, five-year-old P. sylvestris ramets of one clone were directly treated with MeJA, followed by inoculation with H. annosum. In the second experiment, open-pollinated Scots pine seedlings were treated with MeJA by direct spraying and vaporization, and inoculation with H. annosum was done using a slightly modified protocol. In the third experiment, open-pollinated Scots pine seedlings were treated with MeJA by vaporization and inoculated with L. seditiosum. Direct application of MeJA induced seedling mortality, and in some cases, decreased resistance to inoculation with H. annosum. Application of MeJA by vaporization was less stressful for seedlings, and resulted in increased resistance to both H. annosum and L. seditiosum. In addition, an unforeseen Neodiprion sertifer (Geoffroy) and Hylobius abietis L. infestation provided anecdotal evidence of the efficacy of MeJA in inducing resistance to insect pests as well. Further studies are required on the induction of resistance to additional diseases and pests. Induced resistance could be used as a possible protective mechanism for Scots pine seedlings prior to planting during reforestation of stands to increase vitality and survival.

Stratification, Scarification and Application of Phytohormones Promote Dormancy Breaking and Germination of Pelleted Scots Pine (Pinus sylvestris L.) Seeds

Seed quality is an important issue in forestry as it is an essential parameter in the production of high quality planting material. Many factors may hinder the harvesting of high quality seeds, including an insufficient number of sunny days, external conditions in temperate climate zones, and fungal pathogens affecting development of seedlings. We undertook to develop a procedure maximizing seed protection and promoting the optimum physiological development of seedlings by examination of the impact of seed pelleting (a general seed protection method) on germination rates and seedling development of Scots pine (Pinus sylvestris L.). Germination of pelleted seeds was examined in relation to substrate (water vs. soil) and LED light spectrum (white vs. red-blue). Several dormancy breaking treatments were applied: stratification/scarification, and growth regulator treatments including gibberellic acid (GA3), indole-3-acetic acid (IAA) and 1-naphthaleneacetic acid (NAA), to stimulate seed germination. Experiments included independent tests for each treatment (stratification/scarification and plant growth regulators), and combinations of both stratification/scarification and phytohormone treatments. The impacts of these treatments and various controlled germination conditions on the fluorescence of chlorophyll were analyzed using the maximum efficiency of photosystem II photochemistry parameter (Fv/Fm). In addition, chlorophyll a and b content in Scots pine seedlings germinated from pelleted seeds, were quantified using high-performance liquid chromatography (HPLC). The combined stratification/scarification and growth regulator treatment was the most effective germination promoting method for pelleted Scots pine seeds. Scots pine seeds are highly likely to be photoblastic. The best germination rate, while maintaining optimal physiological parameters, was achieved in acidic soil (pH 5.0) with white LED light.

Root influence on soil nitrogen availability and microbial community dynamics results in contrasting rhizosphere priming effects in pine and spruce soil

Abstract The rhizosphere priming effect (RPE) is increasingly considered an important regulator of below‐ground C and N cycling, with implications for terrestrial ecosystem feedback to global change. Even so, there is a lack of knowledge about the mechanisms underlying RPEs. We used novel stable isotope probing methods to investigate RPEs in an experiment with Scots pine and Norway spruce seedlings, two of the most common boreal forest species. We determined root exudation rates, RPEs on SOM decomposition and gross N mineralization, and the contribution of different microbial functional groups to the observed RPEs. Pine induced positive and spruce induced negative RPEs on SOM decomposition, while no RPE on gross N mineralization was observed. Negative RPEs in the spruce treatment were attributed to an opportunistic subset of the fungal community that was growing on root‐derived 13C while depleting available N, thus reducing the activity of microbial SOM decomposers. In the pine treatment, available N was likely sufficient to support the root‐induced decomposition activities of fungal decomposers, resulting in positive RPEs. The findings suggest that RPEs, promoted by root stimulation of distinct subsets of the microbial community, can either contribute to conserving the soil C stock or to depleting it, depending on plant species and soil N availability. A free Plain Language Summary can be found within the Supporting Information of this article.

Early Field Performance of Small-Sized Silver Birch and Scots Pine Container Seedlings at Different Planting Depths

Deep planting is recommended in Nordic countries only for normal-sized container seedlings planted on mounds. Its effects on smaller-sized seedlings are poorly understood. We studied the effects of planting depth on the early field performance of small-sized silver birch (Betula pendula Roth) and Scots pine (Pinus sylvestris L.) container seedlings. Silver birch seedlings (mean height of 16 cm) were planted to depths of 3, 6 and 8 cm on spot mounds in May 2016. Scots pine seedlings (mean height of 9 cm) were planted to depths of 2, 5 and 8 cm on inverted mounds in September 2018 and May 2019. At the end of the first growing season, the deeper-planted birch seedlings were the tallest, as opposed to the deeper-planted Scots pine seedlings. However, the height differences between the planting depths were not apparent until the end of the second growing season in both tree species. Deeper planting decreased damage in Scots pine seedlings in the first growing season, which was not observed in silver birch. Based on our findings, small-sized Scots pine and silver birch seedlings can be planted safely at 6–8 cm planting depths, if at least 20% and 50% of their shoots, respectively, are above ground.

COMPARATIVE ANALYSIS OF THE EXPRESSION ACTIVITY OF SCOTS PINE SEEDLING GENES IN COLD STRESS CONDITIONS

Based on the data of next generation sequencing of transcriptomes of Scots pine seedlings, the genes characterized by induced expression activity under cold stress conditions were identified: xth1, efla, sams, samdc, aqp, aaa+, crt, bi-1, act, a/b-tub, adf, ss/af and pr-3. The data obtained can be used to form a set of candidate genes for diagnosing both the physiological state and cold-tolerant genotypes of Scots pine at the seedling stage.