Low Spring Temperatures Research Articles

Improving Process-Based Modelling to Simulate the Effects of Low-Temperature Stress During Pre-Anthesis on the Quality Characteristics of Wheat Grains.

Low temperatures in late spring pose a potential threat to the maintenance of grain yield and quality. Despite the importance of protein and starch in wheat quality, they are often overlooked in models addressing climate change effects. In this study, we conducted multiyear environment-controlled phytotron experiments and observed adverse effects resulting from low-temperature stress (LTS) on plant carbon and nitrogen dynamics, grain protein and starch formation, and sink capacity. We quantified the relationships between low temperature during the jointing and booting stages and plant nitrogen uptake, grain nitrogen accumulation, grain starch accumulation, grain setting, and potential grain weight using source-sink relationship-based methods. The LTS factor was introduced to account for the cultivar-specific to LTS at different growth stages. Compared with the original model, the improved model produced fewer errors when simulating aboveground nitrogen accumulation, grain protein concentration, grain starch concentration, grain starch yield, grain number, and grain weight under LTS, with reductions of 60%, 71%, 73%, 58%, 50% and 65%, respectively. The improvements in the model enhance its mechanism and applicability in assessing short-term successive frost effects on wheat grain quality. Furthermore, when using the improved model, special attention should be given to the low-temperature sensitivity parameters.

ВПЛИВ ПОГОДНИХ УМОВ НА ЧИСЕЛЬНІСТЬ АМФІБІЙ ТА РЕПТИЛІЙ В УМОВАХ ПРИРОДНОГО ЗАПОВІДНИКА «МЕДОБОРИ» ЗА ПЕРІОД 2016–2020 РОКІВ

Based on the results of long-term observations, the influence of weather conditions on the dynamics of the number and biodiversity of amphibians and reptiles over five years in the "Medobory" nature reserve was analyzed. The number, reproduction, metamorphosis stages, and distribution of amphibians and reptiles depend significantly on climatic conditions. Low temperatures in spring inhibit spawning and larval development. During critical periods, a low amount of precipitation (e.g., 15.7 mm in May 2016, 9.1 mm in April 2018, and 12.1 mm in April 2019, compared to the norm of 45 mm) also negatively affects amphibian populations. This factor led to the disappearance of Triturus cristatus Laur., Lissotriton vulgaris L. (an outbreak was noted in 2014), and Bufo viridis Laur. from the reserve (last observed at MG-1 in 2013), as well as the less common Hyla orientalis Bedriaga. Amphibians and reptiles were recorded during the active period along two regular herpetological routes, MG-1 and MG-2, and observations were made during field research, covering all areas suitable for the reproduction and habitat of amphibians. Eleven species of amphibians have been confirmed in the reserve, belonging to six families: Salamandridae, Bombinatoridae, Pelobatidae, Bufonidae, Hylidae, and Ranidae. Among these amphibians, five species are listed in Appendix II of the Berne Convention, and one species (T. cristatus Laur.) is included in the Red Book of Ukraine. The most common amphibian species are Rana temporaria L., Rana arvalis Nilsson, and Bufo bufo L. Frogs such as Pelophylax lessonae Camerano and Pelophylax ridibundus Pallas occasionally occur within the reserve, as they require an aquatic environment even after reproduction. There are seven species of reptiles in the reserve and one in the immediate vicinity, out of the ten recorded in the Ternopil region. These reptiles occupy the most suitable habitats for their survival. The species represent five families: Emydidae (freshwater turtles), Anguidae (spindly lizards), Lacertidae (true lizards), Colubridae (snakes), and Viperidae (vipers). Common species include Lacerta agilis Andrz., Natrix natrix L., and Anguis fragilis L. Six species of reptiles are included in Appendix II of the Berne Convention, and the common copperhead (Coronella austriaca Laur.) is included in the Red Book of Ukraine.

Assessing the Influence of Planting Dates on Sustainable Maize Production under Drought Stress Conditions

Water is one of the most precious resources and is essential to agricultural output; the biggest user of water is the agricultural sector. Several societal sectors are impacted by the problem of climate change, including agriculture, water resources, and irrigation water demand. A key element in determining sustainable crop production potential is choosing the right cultivars at the right time of year to plant. The dates on which maize is sown are greatly impacted by high summer temperatures and low spring temperatures. Water stress and the timing of sowing can have a significant impact on maize crop yield and water use efficiency. As a result, figuring out the ideal irrigation volume and sowing dates depending on local conditions is essential. A split plot layout was used to create a randomized complete block design for an experiment with five sowing dates (A, B, C, D, and E) and six hybrids (KWS3376, Xinyu 65, KWS9384, Huamei No. 1, Xinyu 102, and Heyu 187). All sowing dates and hybrids had a significant impact on the yield and yield-contributing features (leaf length, ear diameter, grain number per spike, grain breadth, hundred-grain weight, etc.) of maize crops according to the data analysis. A higher grain yield with yield features, such as ear length, number of grains per ear, and hundred-grain weight, was obtained with early-season sowing. Delayed seeding resulted in a lower crop yield. The seasonally delayed seeding of maize reduces yield and yield characteristics. Xinyu 65 produced the highest yield and yield component values of any hybrid. For improved yield and yield traits in the examined area, the study recommended planting maize hybrid Xinyu 65 early in the growing season.

Distinct responses to warming within picoplankton communities across an environmental gradient.

Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year-round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon- and site-specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.

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.

Improving chilling tolerance of peanut seedlings by enhancing antioxidant-modulated ROS scavenging ability, alleviating photosynthetic inhibition, and mobilizing nutrient absorption.

Peanut production is threatened by climate change. Damage to seedlings from low temperatures in early spring can limit yield. Plant adaptations to chilling stress remain unclear in peanut seedlings. It is essential to understand how peanut acquires chilling tolerance. We evaluated effects of chilling stress on growth and recovery of peanut seedlings. We compared and analysed biological characteristics, antioxidants, photosynthesis, biochemical and physiological responses, and nutrient absorption at varying levels of chilling. Compared with chilling-sensitive FH18, the reduced impact of chilling stress on chilling-tolerant NH5 was associated with reduced ROS accumulation, higher ascorbate peroxidase activity and soluble sugar content, lower soluble protein content, and smaller reductions in nutrient content during stress. After removal of chilling stress, FH18 had significant accumulation of O2 •- and H2O2, which decreased photosynthesis, nutrient absorption, and transport. ROS-scavenging reduced damage from chilling stress, allowed remobilization of nutrients, improved chilling tolerance, and restored plant functioning after chilling stress removal. These findings provide a reference for targeted research on peanut seedling tolerance to chilling and lay the foundation for bioinformatics-based research on peanut chilling tolerance mechanisms.

An integrated physiology and proteomics analysis reveals the response of wheat grain to low temperature stress during booting

The low temperature (LT) in spring has become one of the principal abiotic stresses that restrict the growth and development of wheat. Diverse analyses were performed to investigate the mechanism underlying the response of wheat grain development to LT stress during booting. These included morphological observation, measurements of starch synthase activity, and determination of amylose and amylopectin content of wheat grain after exposure to treatment with LT during booting. Additionally, proteomic analysis was performed using tandem mass tags (TMT). The results showed that the plumpness of wheat grains decreased after LT stress. Moreover, the activities of sucrose synthase (SuS, EC 2.4.1.13) and ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) exhibited a significant reduction, leading to a significant reduction in the contents of amylose and amylopectin. A total of 509 differentially expressed proteins (DEPs) were identified by proteomics analysis. The GO enrichment analysis showed that the protein difference multiple in the nutritional repository activity was the largest among the molecular functions, and the up-regulated seed storage protein (SSP) played an active role in the response of grains to LT stress and subsequent damage. The KEGG enrichment analysis showed that LT stress reduced the expression of DEPs such as sucrose phosphate synthase (SPS), glucose-1-phosphate adenosine transferase (glgC), and β-fructofuranosidase (FFase) in sucrose and starch metabolic pathways, thus affecting the synthesis of grain starch. In addition, many heat shock proteins (HSPs) were found in the protein processing in the endoplasmic reticulum pathways, which can resist some damage caused by LT stress. These findings provide a new theoretical foundation for elucidating the underlying mechanism governing wheat yield development after exposure to LT stress in spring.

Inflorescence initiation pattern as affected by air temperature in fall-transplanted intermediate-day onion

ABSTRACT Owing to fall-transplanted onions (Allium cepa L.) grown in temperate zones overwinter, cultivars and agricultural practices have been developed to decrease bolting. Because of climate change, there frequently occur warm winters and low temperatures in spring. Physiological disorders, previously not shown often, deteriorate quality and yield of onion bulbs. This study evaluated the effects of spring temperature on bulb development and inflorescence initiation of intermediate-day onions. Thirty plants (3 replicates of 10 plants) were randomly collected at approximately 5-day intervals from 16 March to 5 June. Plant growth and bolter characteristics were measured, ad the number of lateral leaves and centers, and number of bulb scales in bolted and unbolted onion were counted. Bolting incidence increased three times, first in mid-March, second in mid-April, and last in early-May. Mean daily air temperature preceding increases in bolting incidence were 6.8°C (0.8–13.1°C, min.-max.) in the first 10 days of March, 10.8°C(2.8–18.5°C) from 5 April to 15 April, and 11.8°C (4.7–18.2°C) from 17 April to 28 April. Inflorescences induced after onset of bulbing did not develop into normal spathes and flowers but degenerated into immature umbels and did not produce individual florets. When temperatures after inflorescence induction or bulb initiation, was lower than the temperature required for bulb or inflorescence development, the lateral bud occasionally developed into leaves with leaf blades or swollen sheaths. These results provide information on onion bulb development and inflorescence physiology and to predict onion bolting or splitting in the field.

Emerging Research Advancements to Overcome the Peach Spring Frost

The phenomena of global warming has led to an increase in the average air temperature in temperate climates. Springtime frost damage is becoming more common, and after a period of dormancy, damage to buds, blooms, and developing fruits is greater significant than damage from low winter temperatures. Peaches are a crucial crop among moderate fruits. Spring frost damage in peaches can have a negative effect on crop growth, yield, and quality. It is noteworthy that these plants have evolved defenses against spring frost damage while being exposed to a variety of low temperatures in the early spring. In this current review, recent research advancements on spring frost damage avoidance in peaches were deliberated. Additionally, adaptive mechanisms of peach, such as deacclimation and reacclimation, were emphasized. Moreover, the emerging advancements using various omics approaches revealed the peach physiology and molecular mechanisms comprehensively. Furthermore, the use of chemical products and understanding the spring frost mechanisms through the use of environmental chamber temperature stimulation and infrared thermography studies were also discussed. This review is essential groundwork and paves the way to derive and design future research for agronomists and horticulturalists to overcome the challenges of spring frost damage avoidance and crop management in these circumstances.

Investigation of climate-quality relationship in bread wheat (T. aestivum L.) by novel statistical approach (ESOGÜ quality index)

In this study, precipitation; temperature (maximum, minimum, and average temperature) values of Eskişehir, Konya, Afyonkarahisar, Uşak, and Kütahya for years (2007-2018); and protein content, macro sedimentation (MSDS), thousand kernel weight (KW), test weight (TW) relations, and the effect of climate values on quality were investigated. The Kriging method was used by ArcGIS software for creating quality maps of Eskişehir, Konya, Afyonkarahisar, Uşak, and Kütahya provinces in the light of obtained data from these examined quality criteria, yield, and climate factors. The quality of bread wheat, which includes protein content, macro sedimentation, thousand kernel weight, and test weight, is highly affected by the subject precipitation, maximum temperature, minimum temperature, average temperature, and precipitation. While the months of November, March, and April and the total annual precipitations affect the quality, the most effective precipitation is the months of April and November. Again, the fact that the winter months are hot, especially in January and February, causes the plant to be inadequate to withstand the winter, causing the plant to be more affected by the low temperatures in the early spring and to reduce the quality due to insufficient plant growth. Climatic factors affect quality in total, not alone, but cumulatively. It was concluded that the best quality wheat can be obtained from Konya, Eskişehir, and Afyonkarahisar provinces. It was concluded that ESOGÜ quality index (EQI), evaluating and integrating protein content, macro sedimentation, thousand kernel weight, and test weigh together, can be used safely in bread wheat genotypes.

Regulatory Effect of Exogenous γ-Aminobutyric Acid on Respiratory Rate through the γ-Aminobutyric Acid Shunt in Malus baccata (L.) Borkh. Roots under Suboptimal Low Root-Zone Temperature

Malus baccata (L.) Borkh. is one of the most widely used rootstocks in the apple-producing region of Northern China. However, in the early growing season, apple roots are often subjected to suboptimal low root-zone temperatures. The regulatory effects of exogenous γ-aminobutyric acid (GABA) on both the γ-aminobutyric acid shunt (GABA shunt) and the respiratory activity of roots under suboptimal low root-zone temperatures remain unknown. To explore the physiological basis for GABA alleviation of low-temperature stress in M. baccata Borkh. roots, the following treatments were examined: suboptimal low root-zone temperature (potted parts of the seedlings were maintained at 5 ± 0.5 °C; L); suboptimal low root-zone temperature + GABA (LG); and suboptimal low root-zone temperature + vigabatrin (VGB; LV), which is a specific active inhibitor of γ-aminobutyric acid transaminase (GABA-T). Each treatment was matched with a control (18 °C/8 °C day/night; CK) for comparison. Our results showed that the L treatment reduced the root vitality, increased malondialdehyde (MDA) content, promoted the accumulation of GABA, activated the GABA shunt, and inhibited the total root respiration rate (VTotal) by decreasing the respiratory rates of Embden–Meyerhof pathway (VEMP) and tricarboxylic acid cycle (VTCAC). The LG treatment significantly increased the content of endogenous GABA, accelerated the metabolism of the GABA shunt, enhanced root respiratory activity by increasing VTotal, VEMP, VTCAC, and increased the cytochrome pathway respiratory rate (VCP), thus alleviating the damage of low root-zone temperature stress. Meanwhile, contrasting results were observed in the LV treatment. These findings revealed that exogenous GABA improved the tolerance of apple rootstocks to suboptimal low temperatures in early spring by regulating the GABA shunt and root respiratory activity.

Effect of cold stratification on the temperature range for germination of Pinus koraiensis

Germination at low spring temperatures may offer a competitive advantage for the growth and survival of plant species inhabiting temperate forest ecosystems. Pinus koraiensis is a dominant species in temperate forests of northeastern China. Its seeds exhibit primary morphophysiological dormancy following dispersal in autumn, limiting natural or artificial regeneration: direct seeding and planting seedlings in spring. The aim of this study was to determine the optimum cold stratification temperature that induces germination to increase towards lower temperatures. Seeds from two populations (Changbaishan and Liangshui) were cold stratified at 0, 5 and 10 °C. Germination to incubation temperatures (10/5, 20/10, 25/15 and 30/20 °C; 14/10 h day/night) were determined after 2 and 4 weeks, and 5.5 and 6.5 months of cold stratification. After 5.5 months, approximately 68–91% of seeds from both populations germinated at incubation temperatures of 25/15 °C and 30/20 °C, regardless of cold stratification temperatures. When the cold stratification temperature was reduced to 0 °C and the period increased to 6.5 months, germination at 10/5 °C significantly improved, reaching 37% and 64% for the Changbaishan and Liangshui populations, respectively. After 6.5 months of cold stratification, there was a significant linear regression between cold stratification temperatures and germination at 10/5 °C. The range in temperatures allowing for germination gradually expanded to include lower temperatures with decreasing cold stratification temperatures from 10 to 5 °C and further to 0 °C.

Effect of carbohydrate levels under autumn defoliation on cold tolerance during the subsequent flowering season in pear

Freezing injury to the flowers of deciduous fruit trees is being increasingly emphasized in the context of global warming due to low temperatures in spring. The annual accumulation of nutrients is affected by reserves in the organs during tree growth. In this study, changes in the total carbohydrate (TC), total starch (TS), and soluble solid (SS) content of shoots and changes in cold tolerance and free amino acid (FAA) and free sugar (FS) content of flowers were investigated to determine the effects of carbohydrate and FAA levels on the cold tolerance of pear flowers under autumn defoliation. The freezing injury rate of flowers increased with 50% and 100% defoliation at -2.8 °C. The TC, TS, and SS content in one-year-old shoots decreased after 100% defoliation; the TS content was reduced to one-third. Additionally, the FS and FAA content in flowers at the white-bud stage decreased due to defoliation. In particular, the sorbitol and glutamic acid content decreased after defoliation. These results suggest that maintaining carbohydrate levels is necessary to protect the flowers of pear and other deciduous fruit trees from low temperatures during the flowering season.

Low spring temperature may negatively influence olive yield

The olive tree (Olea europaea L.), a species adapted to the Mediterranean climate, has expanded into new climatic regions. Uruguay has a humid temperate climate and highly irregular climatic conditions among years. Environmental factors can be an obstacle to full production, as they affect pollination and fruit set. In this research, the phenology of five olive cultivars (Arbequina, Arbosana, Manzanilla, Picual and Koroneiki) widely cultivated in Uruguay was studied, using the BBCH phenological scale. The pollen grains of five cultivars were submitted to in vitro germination and incubated at temperatures of 0°, 10°, 15°, 20°, 25°, 30° and 40°C for 24 hours, and pollen grains germination and pollen tube length were evaluated. These temperatures were analyzed for the occurrence probability. They were based on the historical series analysis of hourly average temperature data, from September 26 to November 15 (flowering period), for the years of 1998 to 2019. Phenology results show that flowering can occur from day 268 to day 320 of the year, with cultivar 'Manzanilla' being the earliest and 'Arbosana' the latest. It was observed that the temperature of 10°C has no effect on pollen grain germination and on pollen tube growth. Moreover, the temperatures of 15 to 20°C are not very effective and the optimal temperature occurs between 25 and 30°C. In Uruguay, during flowering, temperatures between 10 and 20°C are more likely to occur. These results indicate possible causes that affect fruit set and productivity of olive trees in the field

The Spatio–Temporal Variation of Spring Frost in Xinjiang from 1971 to 2020

Under the background of intensifying global change, the frequent occurrence of agrometeorological disasters has an adverse impact on the social economy. Low-temperature weather in spring is one of the main agrometeorological disasters in Xinjiang. Studying the spatial and temporal characteristics of low temperatures in spring in Xinjiang is of great significance. However, research on the spatiotemporal variation of spring frost in arid areas is currently lacking, which limits our understanding of the occurrence and development mechanism of typical disastrous weather events in arid areas. Therefore, on the basis of the daily meteorological data of 40 meteorological stations in the Xinjiang Province of China from 1971 to 2020, we studied the spatiotemporal heterogeneity of spring frost in Xinjiang through trend analysis, the Mann–Kendall test, Kriging interpolation, and wavelet analysis. Results showed that the frequency of spring frost had the spatial trend from Northern Xinjiang to Southern Xinjiang. The occurrence frequency of spring frost in the entire and northern region of Xinjiang had an upward trend, whereas that in Southern Xinjiang showed a downward trend. Severe and moderate spring frost events mainly occurred in Xinjiang. The duration of spring frost had the characteristics of Northern Xinjiang to Southern Xinjiang. The spring frost in Northern Xinjiang mainly occurred in April, and that of Southern Xinjiang was in March. Obvious 15-, 10-, and 20-year oscillation cycles were observed in the occurrence frequency of spring frost in the entire, southern, and northern regions of Xinjiang, respectively. This study can provide a useful reference for the prediction and research corresponding to the occurrence mechanism of spring frost in arid areas.

Change in seed dormancy status controls seasonal timing of seed germination in Korean pine (Pinus koraiensis)

AbstractSeed dormancy ensures seedling establishment in the favorable season in a seasonally changing environment. Korean pine (Pinus koraiensis Sieb. et Zucc.) seeds have morphophysiological dormancy after dispersal in autumn. A small fraction of seeds germinates in the first spring, but most seeds germinate in the second spring following dispersal. It is not clear how dormancy status changes and thus drives germination characteristic. Fresh Korean pine seeds were buried between litterfall and soil in Fenglin National Nature Reserves, Heilongjiang Province, northeastern China, in middle October 2018 and regularly exhumed. Field germination percentage, embryo growth, seed viability and laboratory germination percentage of exhumed seeds were determined. The physiological dormancy part of morphophysiological dormancy was gradually released during the first winter, but reinduced in the first summer following dispersal. The reinduced physiological dormancy was broken again in the second autumn and winter. The morphological dormancy part of morphophysiological dormancy was slowly released over the first summer but rapidly broken during the second early and middle autumn. In the second spring, Korean pine seeds completely escaped from morphophysiological dormancy. The physiological dormancy part of morphophysiological dormancy was completely released, but the morphological dormancy part was still maintained, leading to very low germination in the first spring in the field. Relief of morphophysiological dormancy enables a high percentage of seeds to germinate at relatively low temperature (alternating day/night temperature above 10/5 °C) in the second spring. Korean pine provides an example of the change in dormancy status of seeds with morphophysiological dormancy.

Improving wheat yield prediction integrating proximal sensing and weather data with machine learning

• Ensemble learning achieved the best performance for field-scale wheat yield prediction. • Normalized Difference Red Edge Index was the most contributory features. • Average temperature, minimum temperature, and relative humidity were key weather data. • The low temperature and dry air in winter and spring are limiting factors in wheat yield. Accurate and timely wheat yield prediction is of great importance to global food security. Early prediction of wheat yield at a field scale is essential for site-specific precision management. This study aimed to develop an in-season wheat yield prediction model at field-scale by integrating proximal sensing and weather data. Nine multi-N rates field experiments were conducted at five sites involving different wheat cultivars from 2010 to 2020. Proximal sensing data were collected from a Crop Circle sensor at the stem elongation stage and weather data were collected from 30 days before planting to the flowering date. Eleven statistical and machine learning (ML) regression algorithms were adopted, along with two aggregation intervals (disaggregated or aggregated data) and two feature selection methods (based on Pearson Correlation Coefficient or Recursive Feature Elimination). The results revealed that the ensemble learning models (Random Forest, eXtreme Gradient Boosting) achieved the best overall performance (R 2 = 0.74 ∼ 0.78, RMSE = 0.78 ∼ 0.85 t ha −1 ). Feature importance analysis showed that Normalized Difference Red Edge Index (NDRE), average temperature, minimum temperature, and relative humidity were the most contributory features, especially from the planting date to the stem elongation date (for weather features). The aggregation approach and feature selection method did not significantly affect the yield prediction performance for the seven ML methods. This study introduced a promising framework that complements county-scale models and provided insights into understanding yield responses to environmental conditions. The best prediction model can be applied for guiding real-time sensor-based precision fertilization.

Dynamics of seasonal changes in introduced plants in Eastern Transbaikalia

The article presents a comparative analysis of the seasonal development of introduced plants in the weather conditions of Eastern Transbaikalia for the growing periods from 2014 to 2019. The results presented are taken from 6-year phenological observations conducted in the arboretum of the Institute of Natural Resources, Ecology and Cryology SB RAS. We constructed the phenological spectra of the studied objects by year. We studied the main phenological indicators of vegetation the East Asian forest-steppe and Manchurian-Daurian preboreal species. We analyzed the meteorological data: the mean daily air temperatures and precipitation for the months of the growing season (2014–2019), and the sum of active temperatures and precipitation for this period. The data on the dynamics of the development of shrubby plant species in conditions of Eastern Transbaikalia for 2014–2019 indicate that plants respond adaptively to changes in weather conditions. Hereditary and physiological characteristics showed that the introduced plants are characterized as cold-resistant and drought-resistant. Corylus heterophylla and Armeniaca sibirica are most sensitive to temperature extremes in spring, in contrast to Euonymus maackii, which were stable. Low above-zero air temperatures in spring and a large amount of precipitation encourage plants to pass the development stages (phenophases) faster than in dry and warm weather (Corylus heterophylla, Armeniaca sibirica). At the same time, low temperatures (frosts) in spring with a wet period at the time of flowering negatively affect the further fruit formation in Corylus heterophylla individuals. Rainy or cloudy days reduce the color intensity of the autumn leaves, and cool, dry, and sunny weather contributes to the autumn color scheme. Armeniaca sibirica and Corylus heterophylla are variable in terms of the onset of the main phenophases; individuals of the Euonymus maackii species have minimal individual variability. The longest growing seasons on the phenological spectrum were registered in 2014 and 2018–2019 (in Corylus heterophylla individuals – 190 days), which contributes to the accumulation of more phytomass. The shortest growing season was registered in 2015 (Armeniaca sibirica – 150 days).

Prediction of the global potential geographical distribution of Hylurgus ligniperda using a maximum entropy model

Hylurgus ligniperda (Fabricius) is native to Europe but has established populations in many countries and regions. H. ligniperda mainly infests Pinus species, and can cause severe weakness and even death of the host through its boring activity; it can also be a vector of various pathogenic fungi. This study was conducted to investigate the environmental variables limiting the distribution of H. ligniperda and the change trend of its suitable areas under climate change. We used a maximum entropy model to predict the potential geographical distribution of H. ligniperda on a global scale under near current and future climatic scenarios using its occurrence data and environmental variables. The result shows that the areas surrounding the Mediterranean region, the eastern coastal areas of Asia, and the southeastern part of Oceania are highly suitable for H. ligniperda . The environmental variables with the greatest effect on the distribution of H. ligniperda were determined using the jackknife method and Pearson's correlation analysis and included the monthly average maximum temperature in April, precipitation of driest quarter, the monthly average minimum temperature in December, precipitation of coldest quarter, mean temperature of driest quarter and mean diurnal range. Excessive precipitation in winter and low temperatures in spring had a great effect on the distribution of H. ligniperda . The potential geographical distribution of H. ligniperda was predicted to change under future climatic conditions compared with near current climate conditions. Highly suitable areas, moderately suitable areas and low suitable areas were predicted to increase by 59.99%, 44.43% and 22.92%, respectively, under the 2081–2100 ssp245 scenario.

Effects of spring weather on laying dates, clutch size, and nest survival of ground-nesting passerines in abandoned fields

Weather conditions have a significant impact on the life-history strategies of birds. The mechanisms by which weather variability drives demographic processes in boreal passerines have been investigated insufficiently. We examined the effects of spring weather on first egg-laying dates, clutch size, and nest survival of Booted Warbler (<em>Iduna caligata</em>) and Whinchat (<em>Saxicola rubetra</em>) breeding in abandoned agricultural fields in the north of European Russia in 2005–2019. We used general linear models to express first egg-laying dates and clutch size and program MARK to model nest survival as a function of weather variables. Our results demonstrated that variability of May precipitation and averaged daily temperature are important drivers of first egg dates, clutch size, and nest survival in both species. The first egg dates of Booted Warblers and Whinchats were determined primarily by the May temperature: the warmer the weather in May, the earlier the laying dates. Taking into account the effect of the first egg date, the clutch size of Booted Warblers strongly depended on the May averaged daily temperatures, whereas the clutch size of Whinchats was weakly affected by May precipitation. The spring weather had a strong impact on Booted Warbler and Whinchat nest survival, potentially by influencing the activity of nest predators. We suggest that years with a coincidence of low spring precipitation and temperature are the