Late Spring Frosts Research Articles

Integrated analysis of the transcriptome and hormone metabolome elucidates the regulatory mechanisms governing walnut bud germination

The walnut (Juglans regia) is an important oilseed tree species characterized by its extensive distribution, high oil yield, and nutrient-dense kernels, which provide substantial economic benefits. However, the rising incidence of late-spring frosts, exacerbated by global climate change, has adversely affected walnut yields. A comprehensive understanding of the regulatory mechanisms involved in bud dormancy, germination, and development is essential for developing strategies to mitigate the effects of late-spring frosts and for breeding frost-resistant cultivars. This study focused on W13, a protogynous walnut variety with early germination of dormant buds in spring, employing a combination of transcriptomic and hormone metabolomic analyses. Our results emphasized four key biological processes—cellular response to ethylene stimulus, phenylpropanoid metabolic process, ethylene-activated signaling pathway, and monooxygenase activity—along with several relevant pathways, including plant hormone signal transduction, flavone and flavonol biosynthesis, biosynthesis of secondary metabolites, and MAPK signaling pathway, all crucial for walnut bud germination. Additionally, bud germination is closely associated with alterations in various hormone signaling pathways, including abscisic acid, auxin, cytokinin, ethylene, gibberellins, jasmonic acid, and salicylic acid. By assessing hormone levels and gene expression at different developmental stages, we pinpointed potential regulatory genes and critical hormones associated with bud germination. Furthermore, through weighted correlation network analysis, we constructed a co-expression network, identifying gene modules specifically expressed during dormancy, germination, budding, and leafing phases. The hub genes within these modules are likely pivotal in regulating walnut bud germination. Our analysis also revealed that genes from various transcription factor families are central within the co-expression network, indicating their significant roles in the bud germination process. Correlation network analysis of hormone and gene further illuminated the mechanisms through which genes and hormones jointly influence walnut bud germination. These findings establish a crucial molecular basis for a more comprehensive understanding of the mechanisms governing germination and development in dormant walnut buds.

Late spring frost delays tree spring phenology by reducing photosynthetic productivity

Late spring frost delays tree spring phenology by reducing photosynthetic productivity

Flowering in the Northern Hemisphere is delayed by frost after leaf-out

Late spring frosts, occurring after spring phenological events, pose a dire threat to tree growth and forest productivity. With climate warming, earlier spring phenological events have become increasingly common and led to plants experiencing more frequent and severe frost damage. However, the effect of late spring frosts after leaf-out on subsequent flowering phenology in woody species remains unknown. Utilizing 572,734 phenological records of 640 species at 5024 sites from four long-term and large-scale in situ phenological networks across the Northern Hemisphere, we show that late spring frosts following leaf-out significantly delay the onset of the subsequent flowering by approximately 6.0 days. Late-leafing species exhibit greater sensitivity to the frosts than early-leafing species, resulting in a longer delay of 2.5 days in flowering. Trees in warm regions and periods exhibit a more pronounced frost-induced flowering delay compared to those in cold regions and periods. A significant increase in the frequency of late spring frost occurrence is observed in recent decades. Our findings elucidate the intricate relationships among leaf-out, frost, and flowering but also emphasize that the sequential progression of phenological events, rather than individual phenological stages, should be considered when assessing the phenological responses to climate change.

Ring- and diffuse-porous tree species coexisting in cold and humid temperate forest diverge in stem and leaf phenology

Ring- and diffuse-porous tree species coexisting in cold and humid temperate forest diverge in stem and leaf phenology

Early Warning of Late Spring Frost in Apple Orchards of Northwest of Iran

Early Warning of Late Spring Frost in Apple Orchards of Northwest of Iran

Genome-wide identification of the walnut MYC gene family and functional characterization of Xinjiang wild walnut under low-temperature stress.

Introduction: MYC transcription factors are the basic regulators of the jasmonic acid signaling pathway and play important roles in plant growth and development and the response to adverse stress. In recent years, severe winter freezing and late spring frost in the main planting area of walnut in Xinjiang have affected the growth and development of walnut, which has become a prominent problem restricting walnut production. Xinjiang wild walnut is the only remaining wild species of walnuts in China, which contains a lot of genes with excellent traits, and is important for the cultivation and breeding. Methods: In this paper, the physicochemical properties and bioinformatics of MYC transcription factor members in walnut were analyzed, and the nine MYC were screened from the transcriptome data under low temperature stress. At last, we study the subcellular localizations and the expression patterns of the nine MYC members in Xinjiang wild walnut. Results: The results revealed that 30 MYC members were identified from published walnut whole-genome data, and their evolutionary relationships with Arabidopsis and poplar were divided into six groups according to clustering analysis, among which JrMYC22 and JrMYC23 had high homology with PtrMYC2b, which is induced by jasmonic acid in response to low-temperature stress. Walnut MYC members are unevenly distributed on 12 chromosomes. The prediction of promoter cis-acting elements of walnut MYC transcription factor family members revealed that cis-acting elements related to jasmonic acid and lowtemperature stress were the ones with the greatest number of members, with 12. In addition, all nine MYC family members in Xinjiang wild walnut plants responding to low-temperature stress exhibited strong fluorescence responses in the nucleus. The expression levels of these members in response to low-temperature stress revealed that JrMYC28, JrMYC31, JrMYC33, JrMYC34, and JrMYC35 were highly expressed, and it was hypothesized that JrMYC28, JrMYC31, JrMYC33, JrMYC34, and JrMYC35 might play a key role in the response to lowtemperature stress. Discussion: The results of this study provide a theoretical basis for further research on the functional mechanisms of the MYC transcription factor family members in walnut.

New markers for flowering-time selection in sweet cherry

New markers for flowering-time selection in sweet cherry

The Observed Changes in Climate Characteristics in the Trebinje Vineyard Area (Bosnia and Herzegovina)

The productivity and quality of grapes and wine are significantly influenced by changing climate conditions in vineyard regions worldwide. This study assesses changes in temperature, precipitation, and viticultural indices between the periods of 1971–1990 and 2000–2019 in Trebinje, a vineyard area located in the Herzegovina region of Bosnia and Herzegovina. Between the two periods, mean annual temperature increased by 2 °C and mean vegetational temperature by 2.4 °C, while mean precipitation remained within the range of climatological variability, with annual values increasing by 6% and vegetational values decreasing by 4.6%. Warming resulted in a longer duration of the vegetation season by 23.7 days, a reduced risk of late spring frosts, and an increased risk of very high temperatures during summer. These changes led to the reclassification of Trebinje vineyards’ climate from Region III to Region V, based on the Winkler index values, from a “temperate warm” to a “warm” category, based on the Huglin heliothermic index, and from “cool nights” to “temperate nights” based on the cool nights index. The category of the dryness index remained unchanged between the two periods. The findings emphasize the necessity for a renewal of the viticultural zoning and the development of climate change-adaptation plans for this region.

Effect of late spring frosts on the growth and development of garden strawberry

The paper presents the results of research for 2022–2023, as well as the analysis of the effect of prolonged negative late spring temperatures on garden strawberry on May 8-12, 2023. The research was aimed at evaluating garden strawberry varieties for a complex of economically valuable characteristics after exposure to prolonged late spring frosts on May 8–12, 2023. Objects of study included 14 garden strawberry varieties of foreign selection: NF 421, ‘Festivalnaya romashka’, ‘Florida Festival’, ‘Verona’, ‘Dely’, ‘Joli’, ‘Senga Sengana’ (k), ‘Sweetheart’, ‘Syria’, ‘Cabot’, ‘Elianni’, ‘Malvina’ and 2 varieties selected by the Institute: ‘Zvezdochka’ (k), ‘Zhanna’. The plants were planted on May 6, 2022, the survival rate accounted for 100%. The research was conducted in the Research Institute of Horticulture and Medicinal Plants “Zhigulyovskie sady” (Samara, Russia) on the collection variety plot in accordance with the generally accepted program and methodology of varietal study of fruit, berry and nut crops. The analysis of weather conditions for 2022–2023 was performed using the data of the Volga Department for Hydrometeorology and Environmental Monitoring (UGMS), with additional data obtained from the temperature and humidity control system located on the test plot in Malaya Tsarevshchina, Krasnoyarsky District, Samara Oblast. The varieties ‘Verona’, ‘Zvezdochka’ (k), ‘Cabot’, ‘Sweetheart’, ‘Festivalnaya Romashka’, and ‘Malvina’ demonstrated the highest resistance to late spring frosts according to the complex of characteristics. The main part of the varieties had 28-33% damage to flowers and buds. The highest damage figure was revealed in the variety of the average maturity period NF 421 and the early variety ‘Zvezdochka’ (k). The late variety ‘Malvina’ did not suffer from frost.The lowest degree of fruit deformation was observed in the varieties ‘Sweetheart’, ‘Zvezdochka’ (k), and ‘Malvina’. The greatest degree of freezing after exposure to low temperatures on May 8-12 was observed in the varieties ‘Dely’, ‘Joli’, ‘Florida Festival’ and ‘Elianni’. The best adaptive capacity according to the results of overall plant condition for the period 2022-2023 was shown by the varieties ‘Verona’, ‘Zvezdochka’ (k), ‘Senga Sengana’ (k), ‘Cabot’, ‘Sweetheart’, ‘Syria’. The highest average berry weight was recorded in NF 421 (19.5 g/bush). The highest productivity was observed in later ripening varieties – ‘Malvina’ (261.4 g/bush) and ‘Cabot’ (241.0 g/ bush), as well as in the control variety ‘Seng Sengana’ (k) (197.1 g/bush). The lowest indicators were reported in ‘Dely’ (50.1 g/bush) and ‘Florida Festival’ (29.0 g/bush). The genotype was revealed to influence the resistance to low late spring temperatures and recovery ability of plants after late spring frosts.

Morphological and pomological assessments of seedling-originated walnut (Juglans regia L.) trees to select the promising late-leafing genotypes.

In many parts of the world, including Iran, walnut (Juglans regia L.) production is limited by late-spring frosts. Therefore, the use of late-leafing walnuts in areas with late-spring frost is the most important method to improve yield. In the present study, the phenotypic diversity of 141 seedling genotypes of walnut available in the Senejan area, Arak region, Markazi province, Iran was studied based on morphological traits to obtain superior late-leafing genotypes in the cropping seasons of 2022 and 2023. Based on the results of the analysis of variance, the studied genotypes showed a significant variation in terms of most of the studied morphological and pomological traits. Therefore, it is possible to choose genotypes for different values ​​of a trait. Kernel weight showed positive and significant correlations with leaf length (r = 0.32), leaf width (r = 0.33), petiole length (r = 0.26), terminal leaflet length (r = 0.34), terminal leaflet width (r = 0.21), nut length (r = 0.48), nut width (r = 0.73), nut weight (r = 0.83), kernel length (r = 0.64), and kernel width (r = 0.89). The 46 out of 141 studied genotypes were late-leafing and were analyzed separately. Among late-leafing genotypes, the length of the nut was in the range of 29.33-48.50mm, the width of the nut was in the range of 27.51-39.89mm, and nut weight was in the range of 8.18-16.06g. The thickness of shell was in the range of 1.11-2.60mm. Also, kernel length ranged from 21.97-34.84mm, kernel width ranged from 21.10-31.09mm, and kernel weight ranged from 3.10-7.97g. Based on important and commercial traits in walnut breeding programs, such as nut weight, kernel weight, kernel percentage, kernel color, and ease of kernel removal from nuts, 15 genotypes, including no.92, 91, 31, 38, 33, 18, 93, 3, 58, 108, 16, 70, 15, 82, and 32 were superior and could be used in walnut breeding programs in line with the introduction of new cultivars and the revival of traditional walnut orchards to commercialize them.

In vitro salt stress tolerance of ‘Sahand’ cultivar grafted on two wild almond rootstocks: An evaluation of physiological and biochemical traits between rootstocks

The low salinity tolerance of almond cultivars can cause a significant setback in almond production. Therefore, selecting suitable cultivars and rootstocks in salinity-affected areas can facilitate sustainable crop production. In this research, the effects of two wild almond species, Badamkohiand Arjan as rootstocks on the salinity tolerance of ‘Sahand’ as a scion were investigated through in vitro culture. A factorial experiment of 2 (species) × 4 (levels of salinity) was conducted in a completely randomized design (CRD) with 4 replications. The results showed that ‘Sahand’ grafted on Badamkohi had the higher fresh and dry weight than grafted on Arjan in all level of salinity. The Na+ and Cl- ions contents inthe shoots and root of both micrografting combinations increased with increasing salinity. However, their amount in the shoot and the root of ‘Sahand’/Arjan plants were significantly higher than those ions in ‘Sahand’/Badamkohi plants at 80 and 120 mM NaCl. The amount of total chlorophyll in ‘Sahand’ grafted on Badamkohi was 0.68 mg g-1 FW which was significantly higher than the total chlorophyll of the same scion grafted on Arjan rootstock (0.51 mg g-1 FW) at 120 mM NaCl. The highest leaf cell electrical leakage occurred in ‘Sahand’ grafted on Arjan which was significantly higher than leaf electrical leakage of the same scion grafted on Badamkohi at 120 mM NaCl. The grafting combination of ‘Sahand’/Badamkohi showed a higher proline and glycine betaine content, compared to the grafting combination of ‘Sahand’/Arjan. The shoot and root antioxidant enzyme activities (SOD, POX and CAT) in micrografting combination of ‘Sahand’/ Badamkohi were also significantly higher than those in ‘Sahand’/Arjan. It can be concluded that ‘Sahand/Badamkohi combination is a suitable choice for the regions with late spring frost and saline conditions.

Phenological response of European beech (Fagus sylvatica L.) to climate change in the Western Carpathian climatic-geographical zones.

The paper analyzes the results of 26 years (1996-2021) of phenological observations of the vegetative organs of European beech (Fagus sylvatica L.) in the Western Carpathians. It evaluates the influence of the heterogeneity of this territory, including relief and elevation, based on climatic-geographical types. Phenological stages, including leaf unfolding, full leaves, leaf coloring, and leaf fall, were monitored at 40 phenological stations across eight elevation zones. The study assesses trends in the occurrence of phenological stages, the length of the growing season, and phenological elevation gradients. The results indicate a statistically significant earlier onset of spring phenological phases and delay in autumn phases, resulting in an average extension of the beech growing season by 12 days. Our findings confirm that the lengthening of the growing season due to warming, as an expression of climate change, is predominantly attributed to the warming in the spring months. The detected delayed onset of autumn phenophases was not due to warming in the autumn months, but other environmental factors influence it. The trend of elongation of the growing season (p<0.01) is observed in all elevation zones, with a less significant trend observed only in zones around 400 and 600 m a.s.l, signaling changes in environmental conditions across most of the elevation spectrum. Moreover, the heterogeneity of climatic-geographical types within each elevation zone increases the variability in the duration of the growing season for sites with similar elevations. By extending the growing season, it is assumed that the beech area will be changed to locations with optimal environmental conditions, especially in terms of adverse climatic events (late spring frosts, drought) during the growing season. The phenological elevation gradients reveal an earlier onset of 2.2 days per 100 m for spring phenophases and a delay of 1.1-2.9 days per 100 m for autumn phenophases. These findings highlight the specific environmental conditions of European beech in the Western Carpathians and their potential for anticipating changes in its original area. Additionally, these observations can aid in forecasting the further development of phenological manifestations related to climate change.

Evaluation of Frost Tolerance in Sugar Beet Cultivars During Early Growth Stages

Late spring frost is the most hazardous abiotic stress affecting the survival of sugar beet seedlings. Therefore, it is very important to identify frost-tolerant cultivars during the early seedling development stage. In the study, the physiological and morphological responses of ten sugar beet cultivars (Ernestina, Isabella, Orthega, Serenada, Kuno, Taurus, Tuna, Mohican, Rodeo, and Smılodon) to frost stress at different growth stages (V1.1, V2.1, and V3.1) were evaluated. Seedlings were exposed to − 3 °C for 2 h at all stages. Percent damage (%), leaf chlorophyll content (SPAD), leaf surface temperature (°C), electrolyte leakage (%), leaf relative water content (%), and turgidity loss (%) were examined. The results showed that higher damage percentages were observed in earlier growth stages of sugar beet, with recorded values of 29.7% in V1.1, 15.4% in V2.1, and 3.6% in V3.1. A great genotypic variation was observed among the cultivars; electrolyte leakage increased from 15.6% in control to 52.6% in frost stress, and higher electrolyte leakage was obtained from frost-stressed plants. The relative water content of leaves increased only at stage V2.1, although frost decreased turgor loss. Sugar beet showed sensitivity to frost in earlier seedling growth stages, but their tolerance levels increased in later growth stages. The study revealed that electrolyte leakage is a reliable indicator for identifying sugar beet cultivars that exhibit tolerance to frost stress during early development.

Frost matters: incorporating late-spring frost into a dynamic vegetation model regulates regional productivity dynamics in European beech forests

Abstract. Late-spring frost (LSF) is a critical factor influencing the functioning of temperate forest ecosystems. Frost damage in the form of canopy defoliation impedes the ability of trees to effectively photosynthesize, thereby reducing tree productivity. In recent decades, LSF frequency has increased across Europe, likely intensified by the effects of climate change. With increasing warming, many deciduous tree species have shifted towards earlier budburst and leaf development. The earlier start of the growing season not only facilitates forest productivity but also lengthens the period during which trees are most susceptible to LSF. Moreover, recent forest transformation efforts in Europe intended to increase forest resilience to climate change have focused on increasing the share of deciduous species in forests. To assess the ability of forests to remain productive under climate change, dynamic vegetation models (DVMs) have proven to be useful tools. Currently, however, most state-of-the-art DVMs do not model processes related to LSF and the associated impacts. Here, we present a novel LSF module for integration with the dynamic vegetation model Lund–Potsdam–Jena General Ecosystem Simulator (LPJ-GUESS). This new model implementation, termed LPJ-GUESS-FROST, provides the ability to directly attribute simulated impacts on forest productivity dynamics to LSF. We use the example of European beech, one of the dominant deciduous species in central Europe, to demonstrate the functioning of our novel LSF module. Using a network of tree-ring observations from past frost events, we show that LPJ-GUESS-FROST can reproduce productivity reductions caused by LSF. Further, to exemplify the effects of including LSF dynamics in DVMs, we run LPJ-GUESS-FROST for a study region in southern Germany for which high-resolution climate observations are available. Here, we show that modeled LSF plays a substantial role in regulating regional net primary production (NPP) and biomass dynamics, emphasizing the need for LSF to be more widely accounted for in DVMs.

Adaptability of Prunus cerasifera Ehrh. to Climate Changes in Multifunctional Landscape

Urban trees play a vital role in mitigating climate changes, maintaining the sustainability of ecosystems. This study focuses on the assessment of the resilience of cherry plums to climate changes, a fruit-bearing species that offers diverse ecosystem services within multifunctional urban and suburban landscapes. This study examines flowering and fruiting in the context of climate characteristics, expressed through the Day of the Year (DOY), Growing Degree Days (GDDs), and a yield over 17 consecutive years. The results indicate significant shifts in the DOY but not in the GDD, apart from the end of flowering. The onset of flowering was earlier and the end postponed, extending the phenophase by an average of 4 days. The cherry plum’s yield was unaffected by climate changes, including extreme events like a late-spring frost. The stability of the cherry plum was confirmed by the phenological patterns of the bullace (cherry plum and blackthorn hybrid) exhibiting repeated flowering in the warmest year of 2023. The cherry plum is an adaptive species, with a high adaptability to a changing climate and a high resistance to late-spring frosts; thus, it is a favorable choice in urban design and planning, demonstrating resilience to climate shifts and thriving in polluted urban environments. It is especially appreciated for multiple ecosystem services: biodiversity conservation in natural and semi-natural areas, yielding good provisions in challenging environments, and the preservation of ornamental values through an extended flowering phenophase.

Late-Winter and Springtime Temperature Variations throughout New Jersey in a Warming Climate

Abstract Large temperature variations in a temperate climate, particularly in late winter and early spring, can be disruptive for native ecosystems and agricultural crops. As warmer temperatures occur earlier in the year in midlatitude regions as a result of anthropogenic climate change, springtime temperatures may become less consistent, leading to potential damage to species and crops that are vulnerable to the return of historically cooler temperatures, including late-spring frosts, after an initial warm-up. In this work, we quantify shifting patterns in late-winter and springtime temperature variations at eight sites across New Jersey from 1950 to 2019. Many sites located along the coast or in the coastal plain experience increases in the number of times the temperature climbs above 15.5°C (60°F) and then falls below freezing (i.e.,0°C, or 32°F). Sites in southern New Jersey (where much of the state’s agriculture is located) experience the most significant (P &lt; 0.05) increases in large springtime temperature variations. Across all sites, there is a general increase in both the percentage and magnitude of temperature variations that occur as early as February. At 75% of sites, day-to-day variation in daily maximum temperature has increased from the 1950s through 2019; day-to-day variation in daily minimum temperatures has increased over the same time at more than half of sites considered. These amplifications in extreme temperature variations indicate the need for both mitigation and adaptation strategies to protect vulnerable crops and ecosystems in the region during this critical time of the year. Significance Statement Human-caused climate change has made it more likely for warmer temperatures to occur earlier in the year, causing many locations to experience late-winter and early-springtime temperatures that are less consistent than they may have been in the past. These variations can be highly problematic for both vital agricultural crops and critical ecosystems. Here, we evaluate how late-winter and early-springtime temperatures have changed throughout New Jersey (home to a variety of agriculture and unique ecosystems) from the mid-twentieth century until 2019. We find critical changes to temperature patterns during late winter and early spring, including larger and more frequent temperature swings (particularly in February) and increased day-to-day variation in high and low temperatures.

Modeling stabilizing the of orchard managers on the shores of Lake Urmia against late spring frost.

Despite the adverse effects of late spring frost on the ecological and economic impact on agriculture, the management of these events are poorly investigated. Therefore, the grounded theory was used for extracting the livelihood stabilization model of orchardists on the shores of Lake Urmia against late spring frosts. The statistical population of this study in the qualitative part included 22 experts in the field of horticulture. In the quantitative study, they included all orchardists in the villages along with Lake Urmia, comprising 341 people, of which 236 were randomly selected. By carefully examining and linking the concepts and subcategories, the most important subcategories that were included six subcategories. The results of all calculated goodness-of-fit indexes (chi-square [P > 0.01], RMSEA = 0.000, NFI = 0.95, CFI = 0.91, and GFI = 0.92) showed the model provided an excellent fit for the data. Standardized regression coefficients showed that interfering factors had the greatest impact on the livelihood of orchardists against late spring frosts (β = 0.47). Also, the background factors (β = 0.43) and causal factors (β = 0.39) were found to affect the livelihood of the orchardists in encountering late spring frost. The results of multiple square correlations of dependent variables also indicated that about 41% of the livelihood variance of small-scale orchardists was explained by the predictor variables (i.e. causal conditions, background factors and interfering factors). The findings of this study can assist policymakers, planners and relevant managers while paying more attention to orchardists in the region, so as to support decisions in order to achieve sustainable development.

Climate warming disturbances periodicity of Siberian stone pine seed production (Pinus sibirica Du Tour)

Siberian stone pine is one of the main edificator plants of taiga forests of Western Siberia. Sustainable functioning of forest ecosystems depends on its successful cone crops, as its seeds are the basis for the diet of many forest animals. A cone crop in this species is characterized by pronounced interannual variability, manifested in the formation of high seed yields once in 3-4 years. However, in the last 20 years, high yields have been rare, replaced by years with average and low yields. To establish the reasons for these changes, the dynamics of seeding in the period from 1990 to 2023 and weather conditions in spring in the pollination year during the same period were analyzed. It was found that the number of mature cones in the crown largely depended on spring weather in the year of pollination and was negatively correlated with the sum of active temperatures above +5°C accumulated before the late spring frost. If frost occurred at SAT above 300°C, the following year’s crop was minimized. Analysis of weather conditions showed that, on average, there is a tendency to shift the dates of the last frosts to later dates, and even a short-term decrease in temperature to -1 °C leads to complete death of the future crop of cones. Despite the growth of heat availability in the spring period due to active temperature increase in April, the expected shift of frosts to earlier dates is not observed in the south of Western Siberia. For Siberian stone pine, such situation is fraught with strengthening of negative trend in seeding dynamics. It is supposed that at further climate warming the beginning of spring development of reproductive structures will occur at earlier dates, so reproductive structures will be more damaged by late spring frosts, since the latter remain within the same time frames.

Изучение хозяйственно -ценных признаков голубики узколистной (Vaccinium angustifolium Ait .) в условиях г. Москвы

Lowbush blueberry (Vaccinium angustifolium Ait.) is one of the most promising berry crops for cultivation on acid soils in the European part of Russia, but additional testing of varieties and cultivars in the conditions of the Non-Chernozem zone regions is needed. The article presents the results of studies on the phenological and morphological features, evaluation of yield and winter hardiness of V. angustifolium plants of Russian selection (cultivars Lakomka, Neya, Pomorochka, hybrid form NB-60-11) in the natural and climatic conditions of Moscow. As a result of overwintering of the plants in the winter period of 2023-2024 and the impact of recurrent late spring frosts in May 2024, there was no freezing of shoots and damage to flowers. Flowering of V. angustifolium plants in Moscow conditions was observed in mid-May – early June, and lasted for 16-20 days, fruiting was observed in mid-July – late August and lasted for 22-44 days. V. angustifolium plants of the Lakomka cultivar are characterized by the highest annual growth (average 12.9 cm), yield indicators (97.14-182.12 g/bush) and weight of one fruit (average 1.41 g, maximum 2.55 g). The potential of V. angustifolium cultivars of Russian selection for further breeding work and industrial cultivation on unused lands is noted.

Striking differences in frost hardiness and inability to cold acclimate in two Mougeotia species (Zygnematophyceae) from alpine and lowland habitats

AbstractZygnematophyceae, a class of freshwater green algae, exhibit distinctive seasonal dynamics. The increasing frequency of cold snaps during the growing season might challenge the persistence of some populations. The present study explored the frost hardiness of two Mougeotia species isolated from different elevations and habitats. Additionally, a phylogenetic (rbcL sequence), ultrastructural and physiological characterization was performed. Both species, grown under standard culture conditions and cold acclimated cultures (+4°C), were exposed to freezing temperatures down to −9°C. Furthermore, ultrastructural‐, hydrogen peroxide (H2O2)‐ and photosynthetic pigment analysis were performed on cells exposed to −2°C, with and without induced ice nucleation. The alpine M. disjuncta showed a higher frost hardiness (LT50 = −5.8°C), whereas the lowland M. scalaris was susceptible to ice. However, frost hardiness did not improve after cold acclimation in either species but rather decreased significantly in M. disjuncta (LT50 = −4.7°C). Despite darkness, prolonged sub‐zero temperatures or freezing induced the activation of the xanthophyll (VAZ) cycle in M. scalaris. Our results demonstrate that frost hardiness varies within the genus Mougeotia and that the VAZ cycle can be activated in the dark under subzero temperature‐ and freezing stress but does not necessarily increase frost hardiness. As highly frost hardy cell types are usually formed at the end of the growing season, the ability of young cells to survive ice formation in the upper subzero temperature range represents a crucial survival strategy in populations exposed to late spring frosts.