Spring Frost Research Articles

Influence of Climate on Soil and Wine Bacterial Diversity on a Vineyard in a Non-traditional Wine Region in Argentina

Argentina is the fifth world-wide wine producer, with an area of emerging importance in the Southwest of Buenos Aires Province, where climatic conditions are rather challenging. We studied the variations in soil and wine bacterial diversity through three consecutive vintages, and how climatic conditions affected said diversity. During the years of our study there were two harsh climatic events, a prolonged drought that extended over two vegetative periods, and an unseasonable spring frost in 2017. We found that the bacterial diversity reacted to these climatic events, given that there was a shift in the taxa exclusive to soil and wine, and shared by both, through time. Our results show a core of microorganisms in soil as well as in wine, belonging to different phyla that are conserved across the vintage years. A trend to an enrichment in Actinobacteria was detected in soil samples, whereas a high relative abundance of the Acetobacteraceae family and a scarcity of Lactic Acid Bacteria (LAB) were detected in the wine samples. We believe our results contribute to a better understanding of the impact of climatic conditions on the soil and wine microbiota, and can provide vintners with valuable knowledge for improving their wine production.

Threshold‐based characteristics of apricot frost exposure at young fruit in the warm temperate zone, China

AbstractLate spring frost stress is one of the major environmental limiting factors for apricot in the warm zone in China. Investigation of frost exposure of apricot is of particular interest for estimating the frost risk, thus representing the potential damage for apricot production. In this study, daily minimum temperature (Tmin), disaster and phenological data of apricot from 1981 to 2020 in the warm zone were integrated to explore the temperature threshold on apricot at young fruit, facilitating the assessment of apricot frost exposure (E) under the background of climate warming. The daily Tmin was firstly extracted according to the historical disaster records, to identify the per‐ and ongoing weather conditions of the low‐temperature events. The overall accuracy and Receiver Operating Characteristics curve (ROC) were combined to identify the trigger threshold of apricot frost. 1.9°C was identified as the apricot frost trigger threshold in regional assessment, with relatively higher correct rate for disaster (90.2%) and lower incorrect rate for none‐disaster (23.4%). An area under the ROC curve (AUC) of 0.88 was obtained, demonstrating a good performance of Tmin as the trigger factor in discriminating between apricot frost and no frost. High frequency of days suffered from apricot and frost exposure at young fruit were mainly found in the northwestern and middle parts of the region, with frequencies of more than 2 days and E more than 3. Regional days suffered from apricot frost and E were found to have a negative trend with slope −0.0317 and −0.789, respectively, whereas the northwest and middle part of the study region were found to have an increasing trend. The results can provide technical and theoretical support for targeted apricot frost detection and risk assessment, and measures for apricot frost prevention and mitigation can be implemented according to the threshold‐based results.

Plant genotype and seasonality drive fine changes in olive root microbiota

Due to global warming, the cultivation range of many crops is extending at higher altitudes and latitudes exposing plants to new climatic and environmental conditions, as early spring frosts. To face these issues in a sustainable agriculture context, new innovative technologies, as the use of biostimulants and the manipulation of plant microbiota, are emerging. Here, we focused on anarea of Northern Italy in which olive tree cultivation, a traditionally and economically-relevant item of Mediterranean agriculture, is rapidly extending to inland cold-temperate areas. We conducted an assessment of the prokariotic and fungal microbiota present in the root endosphere of a cold-hardy and a cold-susceptible Italian olive cultivar (Leccino and Frantoio, respectively) along spring and winter seasons. Microbiota assembly and diversity analysis revealed that the root microbiotas of more than 20 years-old plants were highly stable with few variations occurring across seasons and genotypes. Notably, we detected fine seasonal-dependent community adjustments in the cold-susceptible genotype, which involved beneficial microbes and pathogens. Moreover, different patterns of abundance were found for arbuscular mycorrhizal fungi and their endobacteria revealing the presence of intimate tripartite interactions. Overall, the results suggest that a healthy and highly stable root microbiota could provide a useful tool to help olive trees to face new environmental issues as those related to climate change.

Earlier and more variable spring phenology projected for eastern Canadian boreal and temperate forests with climate warming

Climate change affects timing and variability of spring phenology, as well as occurrence of spring frosts, and therefore influences forest structure, function, and management practices. In this study, we evaluated changes in budburst timing, sequential order of budburst, budburst temperatures, and frosts, from 1981–2010 baseline to different future climates (+2, +4, and +6 °C for moderate, high, and extremely high warming) for selected boreal and temperate species in eastern Canada. We used species-specific budburst models that are developed from large-scale forcing experiments.Budburst averaged 10–15 days earlier per 2 °C increase of temperatures, except for temperate yellow birch and eastern white pine that slowed down to 5–7 days in budburst advancement from +4 to +6 °C. Earlier budburst was associated with greater annual and interspecific variations in budburst timing, lower budburst temperatures, more frosts, and less annual variations in sequential order of budburst. Compared to temperate trees, boreal trees had greater budburst advances and annual variations, but less interspecific variations in timing and sequential order of budburst. Early flushing species had greater phenological changes and annual variations, as well as more frosts. Our results suggest that budburst advance that has occurred will continue with greater among years/species variability but is unlikely to converge between boreal and temperate regions in eastern Canada under anticipated levels of climate warming.

Growth of 19 conifer species is highly sensitive to winter warming, spring frost and summer drought.

Background and AimsConifers are key components of many temperate and boreal forests and are important for forestry, but species differences in stem growth responses to climate are still poorly understood and may hinder effective management of these forests in a warmer and drier future.MethodsWe studied 19 Northern Hemisphere conifer species planted in a 50-year-old common garden experiment in the Netherlands to (1) assess the effect of temporal dynamics in climate on stem growth, (2) test for a possible positive relationship between the growth potential and climatic growth sensitivity across species, and (3) evaluate the extent to which stem growth is controlled by phylogeny.Key resultsEighty-nine per cent of the species showed a significant reduction in stem growth to summer drought, 37 % responded negatively to spring frost and 32 % responded positively to higher winter temperatures. Species differed largely in their growth sensitivity to climatic variation and showed, for example, a four-fold difference in growth reduction to summer drought. Remarkably, we did not find a positive relationship between productivity and climatic sensitivity, but instead observed that some species combined a low growth sensitivity to summer drought with high growth potential. Both growth sensitivity to climate and growth potential were partly phylogenetically controlled.ConclusionsA warmer and drier future climate is likely to reduce the productivity of most conifer species. We did not find a relationship between growth potential and growth sensitivity to climate; instead, some species combined high growth potential with low sensitivity to summer drought. This may help forest managers to select productive species that are able to cope with a warmer and drier future.

Frost tolerance in apricot (Prunus armeniaca L.) receptacle and pistil organs: how is the relationship among amino acids, minerals, and cell death points?

To the better management of spring frost problem in the apricot cultivars, evaluation of biochemical changes in flower and/or flower organs during bud break could be one of the key factors. In this study, the relationship between the biochemical metabolites such as amino acids and minerals in the receptacle and pistil organs of two different apricot cultivars (frost-sensitive and frost-tolerant) and their relative effects on the frost tolerance of the cultivars and their organs were investigated during full blooming stage. In both apricot cultivars, it was found that the cell death points (CDP) of flower receptacle (- 6.3 to - 8.4°C) were at higher temperatures than the CDP of flower pistil organs (- 13.1 to - 14.5°C). Receptacle organs in flower, therefore, had less tolerance to spring frost damage. In addition, significant differences in mineral and amino acid contents were detected both between apricot cultivars and between the receptacle and pistil organs of the cultivars. Amino acid and mineral contents were lower both in the freezing-sensitive apricot cultivar ("Mihralibey") and the freezing-sensitive organ (receptacle) in comparison with the freezing-tolerant apricot cultivar ("Iğdır Şalak") and the freezing-tolerant organ (pistil). A significant negative correlation was also observed between the mean CDP values and both amino acid and mineral contents in the receptacle and pistil organs of both apricot cultivars. A negative correlation was found between CDP values and glutamate from amino acids and N, K, and Mg from minerals, and also these were determined that they had positive effects on frost tolerance increase. An important finding from our work revealed that the amount of each mineral and amino acid allocated differently to the receptacle and pistil organs of the apricot cultivars. The understanding of the amino acids and the mineral dynamics may contribute to improving the tolerance of flowers of apricot or other deciduous species to frost damage during spring. In the future, we may conclude that protection strategies such as increasing amino acids and mineral content in the receptacle organ of flowers would be necessary to cope with the negative effects of spring frost.

Spatiotemporal Analysis of the Frost Regime in the Iberian Peninsula in the Context of Climate Change (1975–2018)

Climate change is having many effects in the agricultural sector, which are being studied worldwide. Undoubtedly, warmer winters and earlier springs produce changes in frost regimes and severity that will affect the sustainability of agricultural production in the area. The Mediterranean region and the Iberian Peninsula (IP) are among the areas where the greatest impact of climate change is expected. Daily data from 68 weather stations of the IP belonging to the European Climate Assessment and Dataset (1975–2018) were used to conduct a spatiotemporal study of the frost regime. The variables calculated include the probability of three frost types according to their severity, frost day, mean absolute minimum yearly temperature, first frost day, last frost day, and frost-free period. These variables were integrated into a geographic information system, which allowed the graphical visualization of their patterns using of geostatistical interpolation techniques (kriging). Changes in frost variables were investigated using the Mann–Kendall test and Sen’s slope estimator. A general reduction in the number of frosts per year is observed (values between −0.04- and −0.8-day frosts per year), as well as an increase in the mean absolute minimum temperature (values between 0.04 and 0.10 °C per year), with very high significant trends throughout the territory. The reduction in the number of frosts is more pronounced at a higher elevation. Frost dates vary greatly due to the orographic characteristics of the IP. The generalized trend is of a significant delay of the autumn frosts (values between 0.4 and 1.06 days/year), as well as early spring frosts (between −0.429 and −1.29 days/year), and as a consequence a longer frost-free period, all changes were much stronger than those found in other regions of the world. These effects of climate change must be mitigated by modifying species, varieties, and cultivation techniques to guarantee sustainable agriculture.

Resistance of generative organs of sweet cherry to spring frosts after artificial freezing

Aim.The purpose of this research was to study the sustainability of Institute bred sweet cherry cultivars to spring frosts during flowering by the method of artificial freezing and to identify resistant cultivars.Material and Methods. Seven Institute bred sweet cherry cultivars were studied: 'Adelina', "Malysh", "Orlovskaya Rozovaya", "Orlovskaya Feya", "Podarok Orlu", "Siyana" and "Trosnyanskaya". Spring frosts were simulated in an "Espec" PSL-2KPH climate chamber in early May at -1°, -2°, -3° and -4°C. At each temperature regime, 100 pcs of flowers and buds of each cultivar were taken in 3-fold repetition. Temperature was lowered at the rate of 1°C per hour. The duration of exposure to negative temperatures was 3 hours.Results.Damage to the stamens and pistils was assessed by the darkening of the tissues. In buds and blooming flowers after frosts, the pistils were first damaged but the stamens were not. Resistance to spring frosts decreased with the phenological development of the cherry's generative organs. The beginning of damage to the flowers as a result of the artificial freezing was noted at a temperature of -1°C. At the same time, the high stability of cherry buds was noted. Modeling frosts of -2°...-4°C increased the number of dead flowers and buds. The resistance of sweet cherries to spring frosts was found to depend on the genotype and stage of development of reproductive organs. A different sum of active temperatures for the beginning of flowering and ovary formation was noted, indicating the onset of phenological phases in which generative organs are susceptible to spring frosts.Conclusion.The experiment made it possible to distinguish a medium-resistant cultivar "Malysh" which was resistant to spring frosts. Weakly stable genotypes were "Orlovskaya Rozovaya", "Orlovskaya Feya", "Trosnyanskaya" and "Siyana". Unstable cultivars were "Adelina", and "Podarok Orlu". During the formation of the ovary, the greatest potential for resistance to spring frosts was shown by "Podarok Orlu".

Differences in leaf phenological traits between trees and shrubs are closely related to functional traits in a temperate forest

Leaf phenological traits vary greatly with plant species, are thought to relate to leaf functional traits, and play an important role in plant growth. In this study, we investigated leaf phenological and functional traits of 52 woody species (324 individuals) from a natural forest in the Loess Plateau in China. Shrubs obtain a longer leaf life span (LLS) through early leaf emergence and later leaf senescence. Shrubs have a longer LLS compared with trees because they have a greater leaf thickness than trees (to prevent early spring frost), leaf phosphorus content ([P]leaf, related to cell division), and C:N ratio and stem density (to prevent mechanical damage). Among all woody species, species with a small SLA and leaf area and species with thick leaves have a longer leaf emergence duration and LLS, which may be related to material energy reserves. In addition, shrubs had a greater [P]leaf and C:N ratio and a longer leaf emergence duration. Our results reveal differences in leaf phenological traits among life forms and indicate that plant functional traits can provide insight into the mechanisms underlying such differences. In addition, the results of this study provide insight into species coexistence and community assembly in temperate deciduous forests.

Myronosets – a new productive and high-protein winter triticale cultivar, adapted to the woodlands/forest-steppe and forest-steppe of Ukraine

The creation of new triticale genotypes, the potential of which to a certain extent would meet scientific and production needs, will never lose its relevance.
 Purpose and objectives – to create a new productive and high-protein winter triticale cultivar, adapted to the Woodlands/Forest-Steppe and Forest-Steppe of Ukraine.
 Materials and methods. The breeding work to expend the triticale diversity was continued at the Educational and Research Center of Bila Tserkva National Agrarian University in 2007–2017. The control and environmental trials were conducted in 2009-2019 in the Woodlands (Polissya Institute of Agriculture NAAS (2007–2009); predecessor: seeded fallow), central Forest-Steppe (V.M. Remeslo Myronivska Institute of Wheat NAAS (2016–2019); forecrops: mustard, soybean, pea for seeds; Bila Tserkva NAU (2009–2016); predecessors: seeded fallow, potato), and northern Forest-Steppe (Institute of Horticulture NAAS (2016–2017); forecrop: perennial grasses). No mineral fertilizers were applied. No plant protection measures were taken. Hybridization was performed by manual emasculation of female components. Plants were pollinated by the twirl method 2–3 days after emasculation. The breeding material was studied in compliance with the guidelines of the All-Union Research Institute of Plant Breeding and the methodology of the state cultivar trials. Data were statistically processed, as B.А. Dospekhov described, using Statistica-5.5 and Excel-2003 software.
 Results and discussion. We focus on the importance of triticale for mankind both at the present and in the future. We retrospectively reviewed data on the creation of a new winter triticale cultivar, Myronosets. Bioecological features and morphological characteristics of the new cultivar are given. The grain yield and quality are also summarized. The article covers the quantitative parameters of dough and bread from Myronosets grain. We compared the yields, resistance to lodging, in-spike germination, resistance to fungal pathogens and unfavorable abiotic environmental factors in the new triticale cultivar and previously created ones.
 The data of the 2019–2020 state variety trials of Myronosets are analyzed, and they indicate that the new cultivar has a high potential in agroecosystems of the Woodlands and Forest-Steppe of Ukraine.
 Myronosets was found to be a source of the short stem (£90 cm) in subsequent hybrid generations.
 In 2008, interspecific hybridization within the notogenus × Triticosecale and double individual selection from F2–F4 hybrid populations derived from crossing (♀Avhusto x ♂Yahuar) x ♂K9844/93 followed by repeated improving selections in F10 allowed us to distinguish the best line, LCh97, which was later named as cultivar Myronosets.
 The new triticale cultivar can give > 7.5 t/ha. The average yield is 5.7 t/ha in the Forest-Steppe – Woodlands transition belt, 6.3 t/ha in the central Forest-Steppe, and 3.5 t/ha in the Woodlands. It is noticeable for high lodging resistance, high shedding resistance, low spike brashness, resistance to in-spike germination, complex resistance to Puccinia recondita f. sp. tritici Rob. ex Desm (8.5 points), Blumeria graminis (DC.) Speer (9 points.), and Fusarium graminearum Schwabe (8.5 points) and to to the pest Mayetiola destructor Say (8.5 points), high frost tolerance, high winter hardiness, and high drought resistance (8.5–9 points). About 70% of plants survive the laboratory freezing at -18.3°C. The cultivar is also resistant to spring and autumn frosts (9 points).
 Myronosets plants were revealed to be able to regulate their performance under the influence of unfavorable extreme bio- and abiotic factors, leaving 3–4 (more seldom 1–2) fruiting stems, often 1–3 stems with underdeveloped spikes and 1–2 unfertile stems without spikes, which form a radical rosette.
 Conclusions. As it was shown in the state variety trials, Myronosets is a mid-protein cultivar and recommended for cultivation in agroecosystems of the Woodlands and Forest-Steppe. Myronosets was proven to be a source of the short stem

Mapping Threats of Spring Frost Damage to Tea Plants Using Satellite-Based Minimum Temperature Estimation in China

Spring frost damage (SFD), defined as the disaster during the period of newly formed tea buds in spring caused by lower temperature and frost damage, is a particular challenge for tea plants (Camellia sinensis), whose capacity to adapt to extreme weather and climate impacts is limited. In this paper, the region of the Middle and Lower Reaches of the Yangtze River (MLRYR) in China was selected as the major tea plantation study area, and the study period was focused on the concentrated occurrence of SFD, i.e., from March to April. By employing the standard lapse rate of air temperature with elevation, a minimum temperature (Tmin) estimation model that had been previously established was used based on reconstructed MYD11A1 nighttime LST values for 3 × 3 pixel windows and digital elevation model data. Combined with satellite-based Tmin estimates and ground-based Tmin observations, the spatiotemporal characteristics of SFD for tea plants were systematically analyzed from 2003 to 2020 in the MLRYR. The SFD risks at three scales (temporal, spatial, and terrain) were then evaluated for tea plants over the MLRYR. The results show that both SFD days at the annual scale and SFD areas at the daily scale exhibited a decreasing trend at a rate of 2.7 days/decade and 2.45 × 104 ha/day, respectively (significant rates at the 0.05 and 0.01 levels, respectively). The period with the highest SFD risk appeared mainly in the first twenty days of March. However, more attention should be given to the mid-to-late April time period due to the occurrence of late SFD from time to time. Spatially, areas with relatively higher SFD days and SFD risks were predominantly concentrated in the higher altitude areas of northwestern parts of MLRYR for both multi-year averages and individual years. Fortunately, in regions with a higher risk of SFD, the distribution of tea plants was relatively scattered and the area was small. These findings will provide helpful guidance for all kinds of people, including government agencies, agricultural insurance agencies, and tea farmers, in order that reasonable and effective strategies to reduce losses caused by spring frost damage to tea plants may be recommended and implemented.

Sensitivity of Winter Barley Yield to Climate Variability in a Pleistocene Loess Area

Global climate change is predicted to increase temperatures and change the distribution of precipitation. However, there is high uncertainty regarding the regional occurrence and intensity of climate change. Therefore, this work examines the effects of climate parameters on the long-term yields of winter barley and assesses the parameters affecting plant development throughout the year and in specific growth phases. The investigation was carried out in an area with Pleistocene loess, a highly fertile site in Germany. The effect of climate on crop yields was modeled with monthly weather parameters and additional indices such as different drought parameters, heat-related stress, late spring frost, early autumn frost, and precipitation-free periods. Residuals and yield values were treated as dependent variables. The residuals were determined from long-term yield trends using the autoregressive integrated moving average (ARIMA) method. The results indicated that temperature and precipitation are significant in all calculations in all variants, but to a lesser degree when considered as sums or mean values, compared with specific indices (e.g., frost-alternating days, the temperature threshold, the precipitation intensity, rain-free days, the early/late frost index, and the de Martonne–Reichel dryness index). The inter-annual variations in crop yields were mainly determined by the prevailing climatic conditions in winter as well as the transition periods from the warmer season to winter and vice versa. The main winter indices were the temperature threshold, frost-alternating days, and precipitation intensity. During the main growth periods, only the precipitation intensity was significant. These findings can be attributed to the high available field water capacity of this site, which overcomes the need for summer precipitation if the soil water storage is replenished during winter.

Investigation of suitable time for removal vines from the soil or mud for preventing spring frosts

Investigation of suitable time for removal vines from the soil or mud for preventing spring frosts

Machine Learning-Based Hourly Frost-Prediction System Optimized for Orchards Using Automatic Weather Station and Digital Camera Image Data

Spring frosts damage crops that have weakened freezing resistance after germination. We developed a machine learning (ML)-based frost-classification model and optimized it for orchard farming environments. First, logistic regression, decision tree, random forest, and support vector machine models were trained using balanced Korea Meteorological Administration (KMA) Automated Synoptic Observing System (ASOS) frost observation data for March from the last 10 years (2008–2017). Random forest and support vector machine models showed good classification performance and were selected as the main techniques, which were optimized for orchard fields based on initial frost occurrence times. The training period was then extended to March–April for 20 years (2000–2019). Finally, the model was applied to the KMA ASOS frost observation data from March to April 2020, which were not used in the previous steps, and RGB data were extracted by digital cameras installed in an orchard in Gyeonggi-do. The developed model successfully classified 117 of 139 frost observation cases from the domestic ASOS data and 35 of 37 orchard camera observations. The assumption of the initial frost occurrence time for training helped the most in improving the frost-classification model. These results clearly indicate that the frost-classification model using ML has applicable accuracy in orchard farming.

Estimation of Frost Hazard for Tea Tree in Zhejiang Province Based on Machine Learning

Tea trees are the main economic crop in Zhejiang Province. However, spring cold is a frequent occurrence there, causing frost damage to the valuable tea buds. To address this, a regional frost-hazard early-warning system is needed. In this study, frost damage area was estimated based on topography and meteorology, as well as longitude and latitude. Based on support vector machine (SVM) and artificial neural networks (ANNs), a multi-class classification model was proposed to estimate occurrence of regional frost disasters using tea frost cases from 2017. Results of the two models were compared, and optimal parameters were adjusted through multiple iterations. The highest accuracies of the two models were 83.8% and 75%, average accuracies were 79.3% and 71.3%, and Kappa coefficients were 79.1% and 67.37%. The SVM model was selected to establish spatial distribution of spring frost damage to tea trees in Zhejiang Province in 2016. Pearson’s correlation coefficient between prediction results and meteorological yield was 0.79 (p < 0.01), indicating consistency. Finally, the importance of model factors was assessed using sensitivity analysis. Results show that relative humidity and wind speed are key factors influencing accuracy of predictions. This study supports decision-making for hazard prediction and defense for tea trees facing frost.

Ground Frosts in Poland in the Growing Season

The ongoing climate warming affects, among others, and the variability of thermal conditions in spring and autumn are resulting in earlier dates of the beginning and end of the growing season. The present paper provides detailed characteristics of the phenomenon of ground frosts, addressing the question of whether the risk of frost-related damage in the extending growing season is still present. The assessment of temporal and spatial distribution of ground frosts (5 cm above ground level-AGL) in Poland in the thermal growing season (AT > 5 °C) was conducted on the basis of the results of air temperature measurements at 5 and 200 cm a.g.l. obtained from 52 station of the Institute of Meteorology and Water Management—National Research Institute for the period 1971–2020. The thermal growing season was calculated using the method by Gumiński. The following were calculated: the dates of the occurrence of ground frosts in spring and autumn, duration of the frost-free period, the number of days with frosts of various intensity, according to years, ten-day period and days in a year together with trends of change. The conducted analysis demonstrated that the number of days with frosts in the thermal growing season in the multiannual period under analysis (1971–2020) does not show any statistically significant changes. It was found that in the thermal growing season, the average number of days with ground frosts in Poland amounts to 28 and ranges in spring from 15 to 22, and in autumn from 8 to 12. Most frequently, approx. 49%, slight frosts are recorded, followed by moderate (29%), severe (15%) and very severe (7%). A positive effect of water reservoirs on decreasing the frequency and intensity of frosts, as well as sporadic occurrence of the phenomenon in the second half of June were demonstrated. Statistically significant earlier dates of disappearance of frosts in spring, later dates of occurrence in autumn and the lengthening of the frost-free period from approximately 2 days in the north-east of Poland to approximately 8.0 days over 10 years in the Pomerania region, create increasingly more favourable conditions for the cultivation of plants with high thermal requirements in Poland.

Ethylene-Mediated Modulation of Bud Phenology, Cold Hardiness, and Hormone Biosynthesis in Peach (Prunus persica).

Spring frosts exacerbated by global climate change have become a constant threat to temperate fruit production. Delaying the bloom date by plant growth regulators (PGRs) has been proposed as a practical frost avoidance strategy. Ethephon is an ethylene-releasing PGR found to delay bloom in several fruit species, yet its use is often coupled with harmful effects, limiting its applicability in commercial tree fruit production. Little information is available regarding the mechanisms by which ethephon influences blooming and bud dormancy. This study investigated the effects of fall-applied ethephon on bud phenology, cold hardiness, and hormonal balance throughout the bud dormancy cycle in peach. Our findings concluded that ethephon could alter several significant aspects of peach bud physiology, including accelerated leaf fall, extended chilling accumulation period, increased heat requirements, improved cold hardiness, and delayed bloom date. Ethephon effects on these traits were primarily dependent on its concentration and application timing, with a high concentration (500 ppm) and an early application timing (10% leaf fall) being the most effective. Endogenous ethylene levels were induced significantly in the buds when ethephon was applied at 10% versus 90% leaf fall, indicating that leaves are essential for ethephon uptake. The hormonal analysis of buds at regular intervals of chilling hours (CH) and growing degree hours (GDH) also indicated that ethephon might exert its effects through an abscisic acid (ABA)-independent way in dormant buds. Instead, our data signifies the role of jasmonic acid (JA) in mediating budburst and bloom in peach, which also appears to be influenced by ethephon treatment. Overall, this research presents a new perspective in interpreting horticultural traits in the light of biochemical and molecular data and sheds light on the potential role of JA in bud dormancy, which deserves further attention in future studies that aim at mitigating spring frosts.

Impact of successive spring frosts on leaf phenology and radial growth in three deciduous tree species with contrasting climate requirements in central Spain.

Rear-edge tree populations forming the equatorward limit of distribution of temperate species are assumed to be more adapted to climate variability than central (core) populations. However, climate is expected to become more variable and the frequency of climate extremes is forecasted to increase. Climatic extreme events such as heat waves, dry spells and spring frosts could become more frequent, and negatively impact and jeopardize rear-edge stands. To evaluate these ideas, we analyzed the growth response of trees to successive spring frosts in a mixed forest, where two temperate deciduous species, Fagus sylvatica L. (European beech) and Quercus petraea (Matt.) Liebl. (sessile oak), both at their southernmost edge, coexist with the Mediterranean Quercus pyrenaica Willd. (Pyrenean oak). Growth reductions in spring-frost years ranked across species as F. sylvatica > Q. petraea > Q. pyrenaica. Leaf flushing occurred earlier in F. sylvatica and later in Q. pyrenaica, suggesting that leaf phenology was a strong determinant of spring frost damage and stem growth reduction. The frost impact depended on prior climate conditions, since warmer days prior to frost occurrence predisposed to frost damage. Autumn Normalized Difference Vegetation Index data showed delayed leaf senescence in spring-frost years and subsequent years as compared with pre-frost years. In the studied forest, the negative impact of spring frosts on Q. petraea and especially on F. sylvatica growth, was considerably higher than the impacts due to drought. The succession of four spring frosts in the last two decades determined a trend of decreasing resistance of radial growth to frosts in F. sylvatica. The increased frequency of spring frosts might prevent the expansion and persistence of F. sylvatica in this rear-edge Mediterranean population.

Trend and ENSO-based analysis of last spring frost and chilling in Iran

The frost and chilling phenomena are the important climatic and environmental hazards that cause a lot of damage to the agricultural sector every year. In this respect, the present study intends to highlight the possibility of attributed occurrence to large-scale atmospheric indices. In this study, the probability of last spring frost (LSF) and chilling (LSC) at a critical temperature of + 4.4 to − 3.3 °C and different phases of El Nino Southern Oscillation index (ENSO) were extracted using Weibull Distribution Function (WDF) at 18 synoptic stations in a period of 59 years from 1961 to 2019. Then, the anomaly of LSF and LSC occurrence date was investigated in different ENSO phases (EP) and intensities (EI) and finally the LSF and LSC occurrence trend and the factors affecting this trend were analyzed using Mann–Kendall method and Sen’s slope estimator. Different EP and EI were classified using Oceanic Nino Index (ONI) in Nino 3.4 region. The results showed that the occurrence date and probability of the LSF and LSC with different base and critical temperatures in EP are associated with precedence and latency over the whole period and the anomaly of LSF and LSC occurrence date fluctuates between + 17 to − 12 and + 15 to − 17 days, respectively. In addition, the frequency and anomaly of the LSF and LSC at different base temperatures in different EI have been intensified compared to its different EP; therefore, the occurrence date of LSF and LSC can be predicted based on the EP and EI. On the other hand, the trend analysis of the date of the LSF and LSC indicates its retreat towards early spring or last winter at the main studied stations, which is due to global warming. According to the results obtained in some of the studied areas, the delay of LSF and LSC is also observed, which is due to local topographic characteristics, altitude and proximity to moisture sources.

Раннеспелый селекционный материала рапса озимого селекции ВНИИМК: поиск, оценка, выделение перспективных номеров

Early maturing cultivars of winter rapeseed are of a great demand in the modern production as they allow lowering field intensity of harvesting works. Agrarians are interested in the cultivars which can be harvested simultaneously with winter barley and earlier than middle maturing wheat cultivars. Early maturing rapeseed cultivars are less depressed with summer droughts in the southern regions of the Russian Federation, they have shorter and more intensive periods of flowering and ripening. The purpose of our research was to select genotypes of winter rapeseed combining short vegetative period and complex of economically valuable traits in work breeding collection of V.S. Pustovoit All-Russian Research Institute of Oil Crops. We studied 330 breeding samples and selected 13 ones (3.9%) having significantly shortened (by 8–4 days) vegetative period compared to the early maturing standard cultivar Elvis. Also it was selected very early sample YS 5696 of Chinese origin, which ripened by 26 days earlier than Elvis, but having low winter resistance and susceptible to returned spring frosts. The best early maturing samples by yield appeared to be ES-15, МТ-1, МR-2, 787/09, they exceeded to a significant degree the standard cultivar Elvis – by 0.32–0.45 t per ha. Their flowering period started simultaneously with Elvis crops, but their periods of flowering and ripening were quite short. Also the selected samples had meaningfully high oil yield per a unit area (from 1.77 to 1.92 t per ha) compared to the cultivar Elvis (1.66 t per ha), low level of uncontrolled sulphur-containing substances – glucosinolates (from 12.2 to 14.5 µmol/g) and 1000 seeds weight within 3.4–4.1