Spring Frost Research Articles

What are the challenges to producing high quality red wines from interspecific grapes?

In the U.S. Midwest region, interspecific cold hardy grape cultivars have been developed to be resistant to the harsh cold winter, late spring frosts, and hot and humid summer. However, interspecific grape red wines tend to have higher acidity and lower tannins content than Vitis vinifera wines. This leads to unbalanced wines and an increase of the risk of oxidation and therefore impact the overall quality over time. The content and type of phenolic compounds differ in interspecific grapes and wines, depending on the cultivars, the viticultural practices, the environmental conditions and the wine making process. Because the chemical properties of red wines produced from interspecific grapes compared to Vitis vinifera is not well known, it is a challenge to determine the best wine making practices to produce a high quality wine that remains stable over time. This study focuses on evaluating phenolic compounds, oxidation-related compounds, and sulfur dioxide content in Marquette and Frontenac wines aged in bottles for up to 9 years. The goal is to help improve quality of red wines made from interspecific cold-hardy grape cultivars to increase consumer acceptance and develop optimal wine making practices.

Caracterização de novos híbridos de damasco tolerantes a geadas tardias: atributos físicos e bioquímicos de qualidade do fruto, compostos aromáticos voláteis

ABSTRACT: Late spring frosts is one of the most important restricting abiotic stress factors of apricot growing worldwide. In this study; some physical, biochemical fruit quality characteristics and volatile aroma compounds were determined in fresh fruit samples of thirteen late spring frost tolerant apricot hybrids recently obtained from Turkish apricot breeding programme. A wide variation was reported among apricot genotypes in all of the evaluated physical and biochemical fruit characteristics and also volatile aroma compounds.Fruit size varied between 27.2 and 60.5 g, total soluble solids between 13.6 and 17.4 %, total carotene 26.6 and 42.8 (mg.100 g-1), and total phenolics content 354.2 and 673.1 (GAE.100 g-1). A total of 42 flavor components belonging to various flavor compound groups were identified. The main volatile aroma compound groups detected in the assessed apricot genotypes were; aldehydes, ketones, esters, alcohols, terpenes, acids, and other compounds. Among the detected compounds; Hexanal, 2-Hexenal, 1-Hexanol, 2-Hexen-1-ol, Limonene were the most abundant compounds in terms of concentration. Hexanal varied between 55.8 and 528.5 µg.kg-1, and 2-Hexen-1-ol changed between 25.7 and 297.9 µg.kg-1 fresh weight. Correlation analysis revealed significant correlations among some aroma compounds and biochemical fruit quality characteristics. Significant correlations were reported for esters with titratable acidity (r=0.79) and total carotene (r=-0.61) and aldehydes were found as highly correlated with total soluble solids (r=-0.69). The results of the study will be beneficial in terms of food analysis, cultivation, and breeding studies of apricot.

Biomass, carbohydrate, and leakage conductance in buds of six ornamental tree species subjected to a “false spring” in Northeast China

Information is highly scarce about the possible effect of a late spring frost on physiological response of buds in ornamental trees. In this study, spring temperature of Changchun at Northeast China was recorded to identify the characteristics of a false spring by detecting extraordinary warming and sudden freeze in early April of 2017. Buds of six local ornamental tree species were investigated for their dynamics in biomass, non-structural carbohydrates, frost resistance on days of 7, 14, 21, and 28 April 2017. According to a comparison with spring temperature records historically from 2007 to 2016, a false spring was determined. Black pine (Pinus tabuliformis var. mukdensis) had greater bud biomass than apricot (Prunus sibirica L.). Peach (Prunus persica L. var. persica f. rubro-plena Schneid.) reserved greater non-structural carbohydrate content in post-chilling buds than black pine, and apricot and willow (Salix babylonica L.) had greater soluble sugars and starch contents in buds, respectively. Cumulative number of days with temperature below 12°C had a negative relationship with relative conductance in sorbus (Sorbus pohuashanensis [Hance] Hedl.). Chokecherry (Padus virginiana ‘Canada Red’) had greatest bud starch content on 21 April. Overall, a late spring frost imposed interruption on carbohydrate metabolism rather than direct damage on buds of ornamental trees before late April. Advanced warming induced more pronounced negative impact of a false spring than the sudden decline of minimum temperature.

Impact of the B-Plus white pearl (Belyi Zhemchug) preparation on the spring frost tolerance, yield and quality of apple crops

In 2021–2022, experiments were conducted at the Laboratory of Fruit Crop Resistance Physiology, All-Russia Institute for Fruit Crops Breeding (VNIISPK), to investigate the action of the “White Pearl Antifreeze” (Belyi Zhemchug Antifriz) phytomodulator and the “White Pearl Drip Ca + Mg” (Belyi Zhemchug Drip Ca+Mg) phytocorrector produced by the AgroPlus Group of Companies, LLC. Experimental and control plots were characterized by dark-gray forest soils with a humus content of 3-4 % and a humus horizon thickness of 30–35 cm. Apple trees cv. Sinap Orlovsky (VNIISPK) grafted on semi-dwarf rootstock 54-118 were planted in 2013 according to a 6 x 3 m scheme. Natural grassing was used in row spacings; herbicides were applied around the seedlings. The experimental design included: 1) control (water treatment) and 2) foliar treatment with a 1 % solution of “White Pearl Antifreeze” + a 1 % solution of “White Pearl Drip Ca+Mg”. The experiment was conducted in three replications with five observed trees in each. Our aim was to assess the effect of the mentioned preparations on the spring frost tolerance, yield, and quality of apple fruit under the weather conditions of 2021. Foliar treatments with the studied preparations reduced the frost damage to Sinap Orlovsky apple buds by 6.3 % at -3.5 °С and by 10.4 % at -4 °С. The conducted summer foliar treatments with the organomineral mixture under study intensified the growth and ripening of apple fruit. The improved protein-carbohydrate metabolism, water regime, photosynthetic activity, and donor-acceptor leaf–fruit relations increased the fruit weight by 10 g and the yield by 1.8 times. The conclusion is made that the B-PLUS “White Pearl Antifreeze” preparation exhibits a complex effect in terms of increasing plant tolerance to low-temperature spring damage, thus improving the yield and quality of apple crops.

Climate Change, Grape Phenology, and Frost Risk in Southeast England

Background and Aims. The cultivation of grapevines in England is expected to benefit under climate change. Yet assessments of future wine climates remain undeveloped. Accordingly, this study assesses how climate change might modify frost risk for Chardonnay in the Southeast England viticulture region. Methods and Results. Cold-bias-corrected climate projections from the UKCP18 Regional (12 km) perturbed parameter ensemble (PPE) climate model under RCP8.5 are applied with phenological models to determine how frost risk and the timing of key grapevine phenophases might alter under climate change. Notwithstanding the uncertainties associated with projections of key viticulture-related bioclimate variables, the last spring frost was found to advance at a greater rate than budburst, indicating a general decrease in frost risk. Conclusions. Although projections point to an improving climate for viticulture across Southeast England, frost will remain a risk for viticulture, albeit at a reduced level compared to the present. Furthermore, the strong cold-bias found for temperature simulations used in this study needs to be given careful consideration when using the UKCP18 projections for viticulture impact assessments of climate change. Significance of the Study. This study highlights the present sensitivity of viticulture to climate variability and the inherent uncertainty associated with making future projections of wine climate under climate change.

Higher spring phenological sensitivity to forcing temperatures of Asian compared to European tree species under low and high pre-chilling conditions

Winter chilling, spring forcing temperature and photoperiod are the most important drivers explaining the spatial and temporal variability of spring phenology in temperate trees. However, how these factors interact with each other on dormancy release and spring budburst date remains unclear and varies greatly depending on species. Our knowledge is also limited as to whether heat accumulation of forcing temperatures that trigger bud break in spring is a linear or non-linear process. Here, we aimed at experimentally quantifying the effect of chilling, forcing, photoperiod and their interactions on the budburst dates of nine different temperate tree species from East Asia (near Beijing, China) and Central Europe (near Zurich, Switzerland), including six phylogenetically related species (same genus). We conducted a full factorial experiment in climate chambers using two chilling (low and high, i.e., 0 vs. 56 days at 2°C after sampling at the end of December), four forcing (5, 10, 15, and 20°C), and two photoperiod (8 vs. 16 h) treatments simultaneously in Beijing and Zurich. We found that species growing near Beijing responded more readily to forcing conditions than species of the same genus growing near Zurich regardless of chilling treatment. Budburst timing of most species but European beech was marginally, if at all, affected by photoperiod. Furthermore, our results suggest that linear heat accumulation, as commonly used with the growing degree hours (GDH) model, could result in accurate prediction of budburst date depending on the temperature threshold used as a basis for heat accumulation. Our results also demonstrate the important role of chilling in shaping the sensitivity and rate of forcing accumulation to trigger budburst and suggest that species-specific sigmoid relationship for accumulating heat that accounts for prior chilling exposure may yield better predictions of budburst dates. Our results suggest that deciduous trees may have adapted their chilling and forcing requirements in regards to the predictability of winter-spring transition and late spring frosts. A less predictable winter-spring transition, as observed in Central Europe, could have driven species evolution towards higher chilling and forcing requirements compared to species growing in a more predictable climate of Northeastern Asia. Our cross-continental experiment therefore suggests that the spring phenology of East Asian species is tighter coupled to spring forcing temperature than Central European forests.

Evoluția fenofazelor de dezvoltare a unor specii de arbuști fructiferi în Republica Moldova

The paper presents the results of the study carried out regarding the development of the phenological phases of plant development of some species of fruit bushes in the Central area of the Republic of Moldova (the period of bud break, flowering and fruit ripening). It was established that the phenological phases of the studied species: raspberry (Rubus idaeus), black currant (Ribes nigrum), red currant (Ribes rubrum) and white currant (Ribes niveum), gooseberry (Ribes grossularia L.), Josta (Ribes x nidigrolaria), blackberry (Rubus caesius L.), sea buckthorn (Hippophae rhamnoides L.), honeysuckle (Lonicera kamtschatica), blueberry (Vaccinium corymbosum L.), dogwood (Viburnum opulus L.), chokeberry (Aronia melanocarpa Elliott), rose hip (Rosa rugosa Thunb), most of them having an early start in vegetation, which coincides with March, flowering takes place in April, and ripening – in June–July. Exceptions are: honeysuckle, with the earliest vegetation (03–09.03), flowering between 30.03 and 26.04 and ripening fruits in the second half of May (19–25.05); raspberries enter vegetation later (09–21.04), bloom on throughout May, and ripening takes place staggered in June, remontant raspberry varieties begin to bloom in July and ripens staggered in August; blackberry, with the latest onset of vegetation and the latest flowering (18.05–04.06), thus avoiding late spring frosts. Ripening takes place in stages at the beginning of July.

Post-Spring Frost Canopy Recovery, Vine Balance, and Fruit Composition in cv. Barbera Grapevines

Background and Aims. In viticulture, one of the effects of warming trends is the advance of budburst date and the consequent increased risk of spring frost-related damage. In 2021, severe frost events affected a large fraction of European viticulture. In a cv. Barbera vineyard, located in NW Italy, primary bud shoots (PBS), secondary bud shoots (SBS), and suckers (SK) were tagged after the occurrence of freezing temperatures in spring. The goal of the study was to clarify if SBS could partially restore yield loss and analyze their contribution to fruit composition. Methods and Results. The number of developing SBS and SK correlated with the number of killed PBS. While PBS bore 1.44 inflorescences per shoot, SBS had much lower fertility (0.4), with SK at intermediate levels (0.85). The vine yield was 40% of the previous season, with SBS bunches contributing just 17% of the total. SBS produced smaller and looser bunches, as compared with PBS (−28% mass and −27% compactness). At harvest, no difference was found in grape total soluble solids (TSS) among different shoot types. However, the TSS average was notably higher than that observed in the previous season (27.8°Brix vs. 23.3°Brix in 2020). Interestingly, while in PBS and SK, a direct correlation (linear and quadratic, respectively) existed between the leaf area to yield ratio (LA/Y) and grape TSS or total anthocyanins, this did not occur for SBS. Conclusions. In the case of spring frost damage, the number of PBS avoiding fatal injuries will drive agronomic results at harvest since SBS contribution to total yield is modest due to low shoot fruitfulness. The frost-induced increase in vine LA/Y leads to a dramatic rise in grape TSS and phenolics. Significance of the Study. When spring frosts kill a significant number of primary shoots, an altered grape composition at harvest should be expected due to changes in vine balance. Therefore, the vineyard management should be adjusted accordingly early in the season. Further studies are needed to test specific post-frost canopy management strategies ensuring yield, optimal fruit composition, and cane renewal.

Non‐uniform changes of growing conditions for sweet cherry trees responses to climate warming in main production regions of China

AbstractGiven the strong sensitivity of sweet cherry trees to air temperature and the foreseeable warming under future climates, it becomes urgent to analyse spatiotemporal variability of growing conditions in main production areas of China. Here, we estimated changes of three climate metrics, that is, winter chill, heat accumulation and the risk of spring frost events, by using 22 global climate models over the historical and future (represented by central years 2050s and 2085s) time stages. Statistically downscaled daily maximum and minimum temperatures at 14 sites under representative concentration pathway (RCP) 4.5 and 8.5 scenarios were used. The results show a general increase of available winter chill for most sites in Bohai and Lanzhou–Lianyungang Railway line agro‐climatic zones, and the increase in chill accumulation could reach up to 15.2% in these regions for RCP4.5 by 2085 s. However, the most dramatic winter chill decrease is projected to occur in the southwest region under the RCP8.5 scenario by 2085 s. Additionally, the increase rate of heat accumulation during the forcing period shows spatially consistency, and the most pronounced increase is found in the RCP8.5 by 2085 s. In the north region, median heat accumulation increases by 17.5%–21.0% in the 2050 s under RCP4.5. Similar increasing range could be found in the southwest station. High frost risk areas are found in the southwestern region for both baseline and future climate scenarios. Across the 14 study sites, Mengzi and Kunming have the highest meteorologically defined risk of spring damaging frost with accumulated 335 growing degree days (GDDs) and 264 GDDs before the last spring frost event, respectively. Overall, this study provides projected characteristics of site‐specific growing conditions for sweet cherry trees in main production regions. The results could be useful for decision‐making such as selection of appropriate species and varieties in adapting to future warming.

Seasonal variations of cold hardiness and dormancy depth in five temperate woody plants in China

Woody plant species in temperate regions must withstand a cold winter and freezing events through cold acclimation and dormancy in autumn and winter. However, how seasonal changes in dormancy depth and cold hardiness affect the frost risk of temperate species is unclear because few studies have assessed dormancy depth and cold hardiness simultaneously. In this study, an experiment was conducted to estimate the dormancy depth and cold hardiness of five common woody temperate plant species during the winter of 2018/2019 in Beijing, China. Twigs of each species were collected at different dates during winter and the timing of budburst was monitored under the same forcing conditions. The dormancy depth was quantified as growing degree day (GDD) requirements of spring events. Simultaneously, the cold hardiness of buds at each sampling date was determined based on the electrical conductivity of the holding solution. Two indices (chilling accumulation and cold hardiness index) were used to simulate the past dynamics of dormancy depth, spring phenology, and cold hardiness from 1952 to 2021. The maximum dormancy depth of the study species was observed between early October and early December, and thereafter decreased exponentially. The cold hardiness peaked in mid-winter (end of December) through cold acclimation and thereafter decreased in spring (deacclimation). During the past 70 years, the budburst date (first flowering date or first leaf date) of five species was estimated to have advanced significantly, and dormancy depth in early spring was predicted to have increased owing to the warming-associated decrease in chilling accumulation. However, cold hardiness has decreased because of weakened acclimation and accelerated deacclimation under a warming climate. The frost risk before and after budburst remained unchanged because of the reduction in occurrence and severity of low-temperature events and earlier late spring frosts. The present methods could be generalized to estimate and predict the seasonal changes in dormancy depth and cold hardiness of temperate species in the context of climate change.

Weather Conditions, Orchard Age and Nitrogen Fertilization Influences Yield and Quality of ‘Łutówka’ Sour Cherry Fruit

Nitrogen fertilization is a basic agrotechnical orchard treatment, and affects quality and size of the crops. The aim of this study was to assess the impact of nitrogen fertilization on the yield and quality of sour cherry fruit of the ‘Łutówka’ cultivar. The course of climatic conditions in relation to the timing of flowering and fruiting was analyzed. The trials were carried out in three different experimental sour cherry orchards (quarters) with different planting dates (1999, 2001 and 2002) located at the experimental orchard of the Poznań University of Life Sciences in Poland. In each orchard, three levels of fertilization were used: control without fertilization, fertilization at a dose of 60 kg N ha−1 and fertilization at 120 kg N ha−1. Increasing the dose of N did not have a significant effect on sour cherry yield. However, it resulted in a reduction of fruit weight, extract content, acidity and TSS/TA ratio, whereas the brightness (L*) and redness (a*) of the fruit surface color increased. Temperature and precipitation had the greatest influence on the course of flowering, fruiting and fruit ripening. Particularly important was the course of climatic conditions at the beginning of the growing season, especially during flowering, when there is a high risk of spring frosts. The timing of flowering and fruiting was correlated with the sum of active temperatures. The greatest relationship for the flowering date was found for SAT (sum of active temperatures) when the base temperature equals 11 °C and the temperature for the harvest date equals 9 °C.

The effect of climate change on spring frosts and flowering of Crataegus laevigata – The indicator of the validity of the weather lore about “The Ice Saints”

The onset and duration of phenological events are key indicators of the ecological impact of climate change on vegetation. During the flowering time in spring, late frosts are one of the most dangerous meteorological phenomena leading to damage to crops. During 1987–2016, we analyzed the occurrence and intensity of frosts during the period around the weather lore “Frost on the Ice Saints burns all the flowers” in short, “The Ice Saints” and their effects on the flowering phenology of hawthorn (Crataegus laevigata (Poir.) DC.). The late frosts were identified at 0.05 m and2.0 m above ground from temperature measurement data at five phenological stations located from 160 m to 700 m a.s.l. in Slovakia. Results indicate that recent climate change caused the beginning of flowering (BBCH60) for Crataegus laevigata to start significantly earlier by 4.2, 5.0, 6.2 and 3.6 days per decade at 160, 300, 400 and 500 m a.s.l., respectively. Thus, the risk of late frost damage to flowers during “The Ice Saints” is getting highly probable, particularly at 160, 300 and 500 m a.s.l., where the flowering and frosts occur simultaneously. Decreased risk of frost damage during “The Ice Saints” was found at 400 and 700 m a.s.l. It was because of the rare frost occurrence at 400 m a.s.l. in the last decade (2007–2016) of the studied period, and due to the flowering onset dated mostly after “The Ice Saints” at 700 m a.s.l. in the same period.

Identification of key gene networks related to the freezing resistance of apricot kernel pistils by integrating hormone phenotypes and transcriptome profiles

BackgroundApricot kernel, a woody oil tree species, is known for the high oil content of its almond that can be used as an ideal feedstock for biodiesel production. However, apricot kernel is vulnerable to spring frost, resulting in reduced or even no yield. There are no effective countermeasures in production, and the molecular mechanisms underlying freezing resistance are not well understood.ResultsWe used transcriptome and hormone profiles to investigate differentially responsive hormones and their associated co-expression patterns of gene networks in the pistils of two apricot kernel cultivars with different cold resistances under freezing stress. The levels of auxin (IAA and ICA), cytokinin (IP and tZ), salicylic acid (SA) and jasmonic acid (JA and ILE-JA) were regulated differently, especially IAA between two cultivars, and external application of an IAA inhibitor and SA increased the spring frost resistance of the pistils of apricot kernels. We identified one gene network containing 65 hub genes highly correlated with IAA. Among these genes, three genes in auxin signaling pathway and three genes in brassinosteroid biosynthesis were identified. Moreover, some hub genes in this network showed a strong correlation such as protein kinases (PKs)-hormone related genes (HRGs), HRGs-HRGs and PKs-Ca2+ related genes.ConclusionsCa2+, brassinosteroid and some regulators (such as PKs) may be involved in an auxin-mediated freezing response of apricot kernels. These findings add to our knowledge of the freezing response of apricot kernels and may provide new ideas for frost prevention measures and high cold–resistant apricot breeding.

Effects of different winter pruning times on table grape vines performance and starch reserves to face climate changes

In the context of climate change, in which some extreme weather and climate events have increased in frequency and intensity because of global warming, adaptive techniques in viticulture have become necessary to reduce the resulting negative impacts. This study on four table grape cultivars has evaluated the effects of different winter pruning treatments (time of pruning) on phenology, fruit composition and starch content in canes and ≥two-year-old wood. By shifting the pruning time from leaf fall up to budbreak (BBCH 08), a neutral response on yield and berry quality parameters (TSS, TA and pH) was observed for the 4 cultivars. Late pruning treatments resulted in shorter shoot lengths and delayed phenological stages for the early ripening cultivars. The partitioning of starch between canes and older wood was almost similar, although lower in canes, with average values of 13% and a significant reduction at budbreak in order to release soluble sugars for the initial vegetative growth. Starch was mainly located in newly formed xylem, i.e., in the parenchymatic rays where amyloplasts are located, whereas a smaller amount of starch was visible in the other tissues (phloem, cortex). The possibility of a late pruning until over budbreak can be considered a practice to avoid some late spring frost risks, often occurring in viticultural areas. Thus, a ‘precise’ application of winter pruning into a global warming viticulture context could have potential benefits, performing a cost-effective tool management without negative (or very limited for early cultivars) effects on yield and quality of table grapes.

Evaluating late spring frost risks of apple in the Loess Plateau of China under future climate change with phenological modeling approach

Changes in apple phenology associated with climate change have attracted extensive attention. However, it is poorly known whether the phenological dynamics responding to climate change would increase the severity and frequency of frost in apple trees. Here, we investigated the variation of phenophase (budburst and fruit-setting) and the frost risk for apple trees in the Loess Plateau combined with phenology models driven by Global Climate Models (GCMs) under two emission scenarios (SSP2-RCP4.5 and SSP5-RCP8.5 for two time periods 2050s and 2090s, respectively). The results showed that apple budburst and fruit-setting are expected to be advanced to varying degrees, but the rate of advance is decreasing (budburst 0.04–0.14 d∙y−1, fruit-setting 0.12–0.22 d∙y−1). The combinations of high emission scenarios and ‘far’ time periods (SSP5-RCP8.5, 2090s) in budburst and fruit-setting advance larger than conservative emission scenarios and ‘near’ time periods (SSP2-RCP4.5, 2050s). Furthermore, although frost frequency is expected to decrease about 0.09–0.36 d under both SSP2-RCP4.5 and SSP5-RCP8.5, frost intensity tends to increase about 0.004–0.008 °C·d−1 (except SSP5-RCP8.5, 2090s). Due to the different directions of changes in frequency and intensity of frost under future time periods, overall frost risk showed regional differences. The unchanged or decreased frost risk distributed in the northern and southern areas of the study areas, while the increased frost risk mainly distributed across the central areas of the study areas. Finally, the advancement of two phenophase was disproportionately related to frost risks in the geographic distributions. Areas with large advance in phenophase were themselves expected to be at greater frost risk. Our findings will help to promote local preventative interventions for reasonably reducing the risk of late spring frosts in future climate warming scenarios.

Transcriptome Analysis of Apricot Kernel Pistils Reveals the Mechanisms Underlying ROS-Mediated Freezing Resistance

Spring frost is a major limiting factor in the production and cultivation of apricot kernels, an ecological and economic dry-fruit tree in China. The frequent occurrence of spring frost often coincides with the blooming period of apricot kernels, resulting in significant damage to floral organs and reductions in yield. We investigated the molecular signature of pistils from two apricot kernel cultivars with different frost-resistance levels using transcriptome data. A total of 3223 differently expressed genes (DEGs) were found between two apricot kernel cultivars under freezing stress, including the bHLH and AP2/ERF-ERF transcription factors. Based on KEGG analysis, DEGs were mostly enriched in the biosynthesis of the secondary metabolites, in the metabolic pathways, and in plant-hormone signal transduction. The co-expression network, which included 81 hub genes, revealed that transcription factors, protein kinases, ubiquitin ligases, hormone components, and Ca2+-related proteins coregulated the ROS-mediated freezing response. Moreover, gene interaction relationships, such as ERF109-HMGCR1, ERF109-GRXC9, and bHLH13-JAZ8, were predicted. These findings revealed the regulatory factors for differences in frost resistance between the two tested apricot kernel cultivars and contributed to a deeper understanding of the comprehensive regulatory program during freezing stress. Some of the hub genes identified in this work provide new choices and directions for breeding apricot kernels with a high frost resistance.

Cold-Induced Nuclear Import of CBF4 Regulates Freezing Tolerance.

C-repeat binding factors (CBFs) are crucial transcriptional activators in plant responses to low temperature. CBF4 differs in its slower, but more persistent regulation and its role in cold acclimation. Cold acclimation has accentuated relevance for tolerance to late spring frosts as they have become progressively more common, as a consequence of blurred seasonality in the context of global climate change. In the current study, we explore the functions of CBF4 from grapevine, VvCBF4. Overexpression of VvCBF4 fused to GFP in tobacco BY-2 cells confers cold tolerance. Furthermore, this protein shuttles from the cytoplasm to the nucleus in response to cold stress, associated with an accumulation of transcripts for other CBFs and the cold responsive gene, ERD10d. This response differs for chilling as compared to freezing and is regulated differently by upstream signalling involving oxidative burst, proteasome activity and jasmonate synthesis. The difference between chilling and freezing is also seen in the regulation of the CBF4 transcript in leaves from different grapevines differing in their cold tolerance. Therefore, we propose the quality of cold stress is transduced by different upstream signals regulating nuclear import and, thus, the transcriptional activation of grapevine CBF4.

Late pruning of the vine

In the current climatic context, with milder winters leading to earlier budburst in most wine regions, vines are exposed to the risk of spring frosts for a longer period. Depending on the year, frost can lead to yield losses of between 20 and 100 %, jeopardizing the economic survival of wine estates. In addition, by destroying young shoots, spring frosts can impact the following season’s production, by reducing the number of canes available for pruning, for example. Late pruning is one method to combat spring frosts (Ravas, 1912; Frioni et al., 2019).

The Lonely Life of a Champion Tree, Aesculus glabra

Seedlings derived from two Ohio buckeyes (Aesculus glabra Willd.) trees, the National Champion growing in Illinois, USA, and the Ohio State Champion were sampled. The National Champion grows at the northern limits of the species’ native range. The Ohio State Champion grows in Huron County, Ohio, well within the eastern range of the species. We also sampled 40 adult trees growing in Ohio and Illinois. All trees were genotyped at six microsatellite loci. We found that 42 of the 44 sampled seedlings (95%) from the National Champion tree, collected over two seasons, exhibited only maternal alleles at all six microsatellite loci, indicating they were produced by self-fertilization. In contrast, all seedlings from the Ohio state champion tree (N = 48) exhibited non-maternal alleles, indicating they were produced by outcrossing. Our results suggest that when outcross pollen is not available, A. glabra will self-fertilize, but does so rarely or never when outcross pollen is available. Seed germination and early survival were similar for progeny of both champions, but seedlings from the National Champion show lower growth rates and higher mortality during a spring frost, possibly due to inbreeding depression. There was little evidence for genetic structure between trees sampled in Ohio and Illinois.

Hazel (Corylus L.) and hazelnut (Corylus domestica Kos. Et Opal.) pollen

Aim. Wild hazel species (Corylus L.), and hazelnut (Corylus domestica Kos. et Opal.) cultivars are the monoecious anemophilous plants of the birch family (Betulaceae Gray). Due to the early spring catkins bloom of most Corylus, which occurs in March–April in Ukraine, their flowers may be damaged by late spring frosts, causing a decrease in the yield of nuts. That's why the study of the characteristics of the male gametophyte is of general scientific and applied importance for breeding and fruit growing. Methods. Study of pollen of hazelnut cultivars, representatives of C. avellana L., and C. chinensis Franch. from the collection of NDP "Sofiyivka" of the National Academy of Sciences of Ukraine was done using standard methods. Results. It turned out that the pollen of the ‘Sofiyivsky 15’ (cultivar selected from the hybrid population of ‘Garibaldi’×C. chinensis seedlings) had a greater likeness to paternal parent pollen than maternal parent pollen. According to the fertility, size, and shape of pollen grains, the pollen studied by Corylus spp. is characterized by a slight cultivar-form-species polymorphism. Conclusions. The studied species and forms of Corylus L., and Corylus domestica Kos. et Opal. cultivars were characterized by sufficient levels of pollen fertility for their cultivation in hazelnut orchards of all agro-climatic zones of Ukraine.