Autumn Frost Research Articles

Древесные растения и динамика поздневесенних и раннеосенних заморозков в Санкт-Петербурге

Древесные растения и динамика поздневесенних и раннеосенних заморозков в Санкт-Петербурге

Japanese knotweed increases soil erosion on riverbanks

AbstractFor years, Japanese knotweed (Reynoutria japonica) has been suspected of accelerating riverbank erosion, despite a lack of convincing evidence. The stems of this invasive plant die back following the first autumn frosts, leaving the soil unprotected during winter and spring floods. In Québec (Canada), riverbank erosion may also be accentuated by ice during mechanical ice breakups. The objective of this study was to evaluate the influence of knotweed on riverbank erosion along a river invaded by the species, within a context of floods with ice. The elevation along 120 cross‐sectional riverbank profiles, occupied or not by knotweed, was measured before and after the spring flood of 2019. On average, riverbanks occupied by knotweed had nearly 3 cm more soil erosion than riverbanks without knotweed, a statistically significant difference. Stem density also influenced erosion: the higher the density, the greater the soil loss. Certain riverside conditions, such as the slope of the riverbank or being located on an islet, interacted with knotweed, further accentuating erosion. Soil losses measured between November 2018 and May–June 2019 were particularly pronounced, but the spring flood was also exceptional, with a recurrence interval close to 50 years. On the other hand, soil loss from rivers invaded by knotweed can be expected to increase over time, as this invasive species spreads rapidly in riparian habitats.

Phenological variability and resistance to late spring frost of common beech in the international provenance test in Bosnia and Herzegovina

The research aimed to determine the start, end and duration of leafing phases, the degree of plant damage caused by late spring frost, and the retention of leaves in autumn. The research was conducted in the international common beech provenance test in Bosnia and Herzegovina. The test contains eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania and Switzerland, and one from Hungary. Leafing phenology, canopy damage caused by late spring frost, and leaf retention were assessed in 2019. Most provenances started opening buds on 17 April 2019. Complete canopy damage affected the highest percentage of plants in provenance BW Bad Wildbad, Germany (68 %), and the lowest in provenance Konjuh Kladanj, Bosnia and Herzegovina (3.2 %). Provenance Herzogenbuchsee from Switzerland had the highest percentage of winter leaf retention (37.5 % of plants). The results can be used in choosing provenances that are resistant to low temperatures in zones of late spring and early autumn frost.

Modern aspects and results of sweet pepper breeding in Western Siberia

Relevance. In Siberia, sweet pepper is grown both in the open and in the protected ground. For a short Siberian summer, it is important to have varieties adapted to the local bioclimatic potential: early ripening, for obtaining valuable products in the middle of summer, and the possibility of conducting seed production. The priority direction is the creation of varieties that are resistant to abiotic and biotic environmental factors, with high yield, product quality, and high vitamin C content.Materials and methods. The research was carried out in film unheated greenhouses and in the open ground at the West Siberian Vegetable Experimental Station-a branch of the Federal Research Center for Vegetable Growing. The material for research was collected, selected samples, varieties of pepper.Results and discussion. Breeding work on the culture of sweet pepper at the West Siberian Vegetable Experimental Station was started in the late 60s of the last century, active work – in the early 90s. The conditions of the sharply continental climate, with its mild frost-free period, require the creation of varieties capable of obtaining a commercial pepper crop, despite the negative impact of biofactors. The use of precocious varieties gives a guaranteed harvest by avoiding early autumn frosts. Breeding for precocity is one of the main directions of Siberian breeding. Over the years of selection, models of future varieties were created, more than 20 varieties of sweet pepper of various varietal types were created. The varieties obtained at the station all belong to the early-maturing group, with a period from germination to the first fruit harvest-98-116 days, a height of 40-80 cm during the fruiting period, compact, suitable for growing without a garter to the trellis. As a result of a comprehensive assessment of the initial breeding material, donors of economically valuable traits were selected, the inclusion of which in the breeding process contributed to the creation of a number of precocious pepper varieties of various variety types. The created varieties have a high biological potential in terms of adaptability, productivity, and biochemical parameters. Suitable for growing in various production sectors.

Influence of basic tillage on the productivity of leguminous crops

The studies were carried out in order to identify the most effective method (plowing, loosening, their alternation in crop rotation, without main processing) of a mid-depth (20-22 and 12-14 cm) main processing of leached heavy loamy chernozem during cultivation of grain legume crops (peas, chickpeas) in the northern forest-steppe Tyumen region. The work was carried out in 2016–2019. Meteorological conditions in the study area are characterized by long cold winters, warm short summers, short spring and autumn, late spring and early autumn frosts. The highest yield of legumes was noted after plowing by 20-22 cm, so when cultivating peas, it was higher than after loosening to a similar depth, by 0.39 t/ha, chickpea - by 0.53 t/ha, compared with the option of alternating plowing and loosening in crop rotation, by 0.38 and 0.32 t/ha, respectively. With a decrease in tilling depth, the yield of peas and chickpeas decreased: for plowing - by 0.32 and 0.35 t/ha, after loosening - by 0.33 and 0.30 t/ha, in the variant with alternating plowing and loosening - by 0.26 and 0.21 t/ha. The lowest yield in the experiment was noted without basic tillage. The best results after plowing at 20-22 cm were due to the highest yield, as well as the highest mass of 1000 grains, the yield of fodder and grain units in this variant.

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.

Influence of growth regulators on the yield and quality of potatoes.

The potato is one of the most versatile, accessible and at the same time widespread vegetable crops of the globe, and in particular of the Russian Federation. Today notable can be imagined without it. But despite the plasticity of the potato crop, there are still “white spots” in its production. With late and even return spring and early autumn frosts, the climatic features of Siberia significantly affect the crop’s growing season, preventing it from realising its full potential. Like that of many other crops, potato production is associated with seasonality, and there are often significant losses during cultivation and especially during storage. An important challenge is to protect plants during growth and development by applying innovative, environmentally friendly crop protection and stimulation products. Organomineral growth and development regulators were particularly popular. In the work schemes of application of perspective, organomineral growth regulators in conditions of forest-steppe of Western Siberia were tested and perfected. Their influence on the primary phases of growth and development of potatoes and their maturity, and their influence on biometrical parameters of plants, a phytosanitary condition of crops, a crop capacity, and its safety are established. On average, under the influence of growth regulators Epin-Extra and Zircon, the growing season is shortened by 3-5 days; the spread of diseases is reduced by 1.5-2 times; the yield increases to 8.3 tons per hectare. These studies are confirmed by the calculation of economic efficiency. Thus, the use of these growth regulators provides the level of profitability of production up to 252%.

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

Siberian plants shift their phenology in response to climate change.

Siberia has undergone dramatic climatic changes due to global warming in recent decades. Yet, the ecological responses to these climatic changes are still poorly understood due to a lack of data. Here, we use a unique data set from the Russian 'Chronicles of Nature' network to analyse the long-term (1976-2018) phenological shifts in leaf out, flowering, fruiting and senescence of 67 common Siberian plant species. We find that Siberian boreal forest plants advanced their early season (leaf out and flowering) and mid-season (fruiting) phenology by -2.2, -0.7 and -1.6days/decade, and delayed the onset of senescence by 1.6days/decade during this period. These mean values, however, are subject to substantial intraspecific variability, which is partly explained by the plants' growth forms. Trees and shrubs advanced leaf out and flowering (-3.1 and -3.3. days/decade) faster than herbs (-1day/decade), presumably due to the more direct exposure of leaf and flower buds to ambient air for the woody vegetation. For senescence, we detected a reverse pattern: stronger delays in herbs (2.1days/decade) than in woody plants (1.0-1.2days/decade), presumably due to the stronger effects of autumn frosts on the leaves of herbs. Interestingly, the timing of fruiting in all four growth forms advanced at similar paces, from 1.4days/decade in shrubs to 1.7days/decade in trees and herbs. Our findings point to a strong, yet heterogeneous, response of Siberian plant phenology to recent global warming. Furthermore, the results highlight that species- and growth form-specific differences among study species could be used to identify plants particularly at risk of decline due to their low adaptive capacity or a loss of synchronization with important interaction partners.

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.

AGRICULTURAL CLIMATE RISK ZONING FOR GLADIOLUS IN SANTA CATARINA

This work aims to developing an Agricultural Climate Risk Zoning for gladiolus in the State of Santa Catarina. The bioclimatic requirements and the risk criteria were defined for the crop through a bibliographic review. The probability of frost occurrence, water balance and frequency of maximum air temperatures above 34°C were calculated with meteorological database. A maximum assumed risk of 20% was considered. The period when planting is not recommended was determined for each of the development cycles (early, intermediate I and II and late). It was observed that low temperatures and occurrence of frost in autumn and winter limits gladiolus planting in the State of Santa Catarina. Analysis of the water balance indicated there is risk of water deficiency throughout the year, which varies according to the locations. Maximum air temperatures above 34oC do not occur frequently in the State. In the Coastal regions, there are no restrictions to planting throughout the year. The Agricultural Climate Risk Zoning indicate the potential for gladiolus farming in Santa Catarina, where the greatest planting potential is in the Coastal, West and Extreme West regions.

Agrometeorological Conditions and Agroclimatic Trends for the Maize and Wheat Crops in the Balkan Region

The Balkan peninsula is a transitional zone, in terms of bioclimatic conditions, with an extended and dynamic agricultural sector. Its potential is in peril due to climate change and socioeconomic factors. To assess and evaluate the agrometeorological conditions and the related trends which affect the widely cultivated wheat and maize, a big dataset with high spatiotemporal analysis was utilized. The thermal indices of Growing Degree Days (GDD) and Heat Stress Index (HSI) along with the main frost parameters (frost days, last spring frost, first autumn frost, and free of frost days) were calculated over ten countries for 42 years on a daily basis over a grid of 25 × 25 km. The results indicate a clear cultivations’ expansion ability to northern areas, and higher altitudes and an increased risk of heat caused plants’ injuries. The thermal indices’ trends for maize and wheat cultivation are always positive (Maize: GDD 7.26–11.05 units/yr, HSI 0.52–3.51 units/yr Wheat: GDD 7.2–12.7 units/yr, HSI 0.22–1.77 units/yr). The free of frost (FFD) season is getting longer (trend −0.04 to 0.34 d/yr) because of earlier last spring frost and delayed first autumn frost. The results consist of spatial and temporal illustrations, along with summary statistics and probability density plots for the entire study area and per country.

Autumn cold acclimation of shoots does not explain the northern distribution limit of three southern exotic tree species in Finland

Frost hardiness (FH) is one of the key traits that limits the distribution of tree species in the north. Different species and ecotypes respond differently to the drivers of frost hardening and may therefore have different survival capacities, especially in their northern distribution range. Several southern tree species such as pedunculate oak (Quercus robur L.), Norway maple (Acer platanoides L.), and mountain elm (Ulmus glabra Hudson) have their natural northern distribution limit in Southern Finland. Here, we examined whether insufficient frost hardening in the autumn limits the northwards distribution of these three species. To that end, we monitored phenological events and frost hardening in the autumn in these exotic species in Central Finland, further north from the natural distribution range of the three exotic species, and for the sake of comparison, in the native silver birch (Betula pendula Roth.). In all species, a timely growth cessation was observed. The water content of the stem decreased, and its dry mass content increased rapidly in August before the onset of frost hardening, after which no major changes were observed in these two traits. In the early phase of hardening, there were differences in leaf colouring between the four species. The values of the electrical impedance parameters of the stem changed during frost hardening, with a clear turning point after the first night frosts at the end of September. Depending on the species and hardening phase, the high temperature exotherm (HTE) of the stem was observed between -3 °C and -10 °C, but HTE did not indicate differences between the species in frost hardening. In all four species, frost hardening started at the beginning of September and proceeded first at equal rates, but the hardening was more rapid later in birch than in the other species. The damaging temperature range assessed by the controlled freezing tests became wider with increasing FH. The occurrence rate of the low temperature exotherm (LTE) varied between the species, and the LTE was observed at around -35 °C in the last sampling at the beginning of December (no LTE was observed in birch). We conclude that the hardening of all four species took place in a timely manner so that in each, the frost hardiness was sufficient to survive the autumn frosts at the experimental site in Central Finland. Further studies are needed to examine whether the exotic three species also tolerate temporarily occurring extreme winter conditions such as temperatures below -35 °C, and the high short-term temperature variations in winter and especially in spring.

Natural temperature fluctuations promote COOLAIR regulation of FLC.

Plants monitor many aspects of their fluctuating environments to help align their development with seasons. Molecular understanding of how noisy temperature cues are registered has emerged from dissection of vernalization in Arabidopsis, which involves a multiphase cold-dependent silencing of the floral repressor locus FLOWERING LOCUS C (FLC). Cold-induced transcriptional silencing precedes a low probability PRC2 epigenetic switching mechanism. The epigenetic switch requires the absence of warm temperatures as well as long-term cold exposure. However, the natural temperature inputs into the earlier transcriptional silencing phase are less well understood. Here, through investigation of Arabidopsis accessions in natural and climatically distinct field sites, we show that the first seasonal frost strongly induces expression of COOLAIR, the antisense transcripts at FLC Chamber experiments delivering a constant mean temperature with different fluctuations showed the freezing induction of COOLAIR correlates with stronger repression of FLC mRNA. Identification of a mutant that ectopically activates COOLAIR revealed how COOLAIR up-regulation can directly reduce FLC expression. Consistent with this, transgenes designed to knockout COOLAIR perturbed the early phase of FLC silencing. However, all transgenes designed to remove COOLAIR resulted in increased production of novel convergent FLC antisense transcripts. Our study reveals how natural temperature fluctuations promote COOLAIR regulation of FLC, with the first autumn frost acting as a key indicator of autumn/winter arrival.

Young Field-grown Kiwifruit Plants’ Response to Early Autumn Frost Injury in Texas

Two-year-old, field-grown golden kiwifruit (Actinidia chinensis) and fuzzy kiwifruit (Actinidia deliciosa) plants were evaluated for injury following an early freeze event of −4.1 °C on 14 Nov. 2018 in Burleson County, TX. Plant material included seven cultivars: one seed-propagated [Sungold™ (ZESY002)] and three cutting-propagated golden kiwifruit (AU Golden Dragon, AU Golden Sunshine, CK03), and one seed-propagated (Hayward) and two cutting-propagated fuzzy kiwifruit (AU Authur and AU Fitzgerald). Observations were made 5 weeks after the frost event. Base trunk diameter (BD) and maximum trunk diameter damaged (MDD) provided a reference of plant size and crude measurement of damage intensity, as evident by presence of water-soaked necrotic and/or dehydrated tissue following the removal of a thin slice of periderm, vascular cambium, phloem, and xylem. Percent of base diameter damaged (PBDD) was calculated as MDD divided by BD and provided an assessment of damage, unbiased by plant size. Percent of shoot damaged (PSD) was visually evaluated as the percentage of entire shoot system exhibiting damage. In addition, presence of basal damage (DB) and basal cracking (CB) were recorded. A strong cultivar response was observed for BD, MDD, PBDD, and PSD. Mean cultivar values for PSD ranged from 79% and 19% for AU Authur and Sungold™ seedlings, respectively, which represented extremes among cultivars. Fuzzy kiwifruit exhibited greater injury (PBDD, PSD, DB, and CB) as compared with golden kiwifruit cultivars. Basal damage and basal cracking proved unique to fuzzy kiwifruit, as DB ranged from 0% in Sungold™ seedlings to 100% in fuzzy kiwifruit ‘AU Authur’ and ‘AU Fitzgerald’. In spite of having greater vigor, golden kiwifruit plants sustained less injury. Method of propagation had no effect on injury. PBDD and PSD proved to be reliable field assays for documenting injury, based on their strong correlation value (r = 0.92). Greater relative autumn frost tolerance of golden kiwifruit over fuzzy kiwifruit cultivars is previously unreported.

Effect of biostimulant application on development of pansy (Viola tricolor var. Hortensis dc.) seedlings

Pansy (Viola tricolor var. hortensis DC.) is a biennial large-flowered hybrid plant cultivated as a popular ornamental plant in urban green areas. The plants prefers sun and well-drained soil, but also tolerate low temperatures. The optimal time for transplanting pansy seedlings in outdoors beds is in autumn, although early autumn frosts can affect the insufficient nutrient uptake, which can be a limiting factor for seedling survival. To avoid these effects, plants can be treated with different growth stimulants such as the biostimulant Radifarm®. The aim of this study was to investigate the effects of biostimulant Radifarm® application on development of pansy seedlings. The experiments were carried out in the glasshouse of the Faculty of Agriculture in Banja Luka, Bosnia and Herzegovina, set up as a split-plot design with treated and untreated plants during 2014 and 2015. In the greenhouse, young plants were treated with biostimulant Radifarm® (Valagro SpA, Italy) in concentration of 0.30% while control plants were treated only with tap water. During the experiment, the following parameters were recorded: plant height (cm), plant diameter (cm), number of leaves, and number of flowers. At the end of the experiment root and above-ground fresh, and dry mass were recorded. Biostimulant treatment showed improved results by increasing the examined parameters. Biostimulant application can ensure production of high quality pansy seedlings by overcoming temperature stress and providing good nutrient uptake by the reduction of fertilizers and environmental contamination.

Adaptive performance of genetically improved and unimproved seedlings of Scots pine

Our main objective was to determine whether various genetically improved reproductive materials of Scots pine ( L.) differ in growth rhythm, autumn cold acclimation and resilience from unimproved materials. The study consisted of two successive indoor experiments with Scots pine seedlings representing four levels of genetic gain (unimproved natural stands, first-generation seed orchards, 1.5-generation seed orchards and seed orchards established with freezing-tested parents) and a wide range of geographical origins within Finland. The seedlings were assessed for terminal shoot elongation, growth cessation, bud set, freezing injuries and bud flushing over the first growth period. All the adaptive traits showed a latitudinal trend regardless of the genetic level. Seed orchard progenies and natural stand progenies did not differ significantly in the timing of growth cessation, bud set, and the flushing rate of the frost-injured seedlings, after the trait variation was adjusted to the latitude of origin. The differences in autumn frost hardiness were insignificant, too, except for the somewhat higher injury rate displayed by the first-generation seed orchard materials. The finding was not conclusive due to ambiguous results from the two experiments. Overall, we did not find evidence of alarming compromises in the adaptive performance of genetically improved materials.Pinus sylvestris

Divergent patterns between phenotypic and genetic variation in Scots pine

In boreal forests, autumn frost tolerance in seedlings is a critical fitness component because it determines survival rates during regeneration. To understand the forces that drive local adaptation in this trait, we conducted freezing tests in a common garden setting for 54 Pinus sylvestris (Scots pine) populations (>5000 seedlings) collected across Scandinavia into western Russia, and genotyped 24 of these populations (>900 seedlings) at >10 000 SNPs. Variation in cold hardiness among populations, as measured by QST, was above 80% and followed a distinct cline along latitude and longitude, demonstrating significant adaptation to climate at origin. In contrast, the genetic differentiation was very weak (mean FST 0.37%). Despite even allele frequency distribution in the vast majority of SNPs among all populations, a few rare alleles appeared at very high or at fixation in marginal populations restricted to northwestern Fennoscandia. Genotype–environment associations showed that climate variables explained 2.9% of the genetic differentiation, while genotype–phenotype associations revealed a high marker-estimated heritability of frost hardiness of 0.56, but identified no major loci. Very extensive gene flow, strong local adaptation, and signals of complex demographic history across markers are interesting topics of forthcoming studies on this species to better clarify signatures of selection and demography.

STUDYING THE IMPACT OF EARLY AUTUMN AND LATE SPRING FROSTS ON AGRICULTURAL CROPS YIELD IN IRAN

To study early autumn and late spring frosts and its relation to the yield of agriculture crops in Semnan province we used statistics the least daily minimum temperature of 6 stations in the months of October and November and April during the period (1993-2014) as well as information on yield of agricultural crops from horticulture department of agriculture Organization. Using Pearson correlation coefficient between yield and frequency of early autumn and late spring frosts were studied and finally induced to study the frosts trends for each station. Early frosts of autumn in the province date from 20 October to 23 November and latest frosts ranged from 3 to 23 April and Biarjomand station experience earliest autumn and latest spring frosts. The Relationship between crop yields with frost Occurrence frequency shows that by increasing the number of days of early autumn frosts reduced wheat yield. This condition is for crops such as peas, walnuts and grapes, too. Amongst, the greatest impact is on the potato crop, which is closely related to the pattern of cultivation and harvest. On the other hand, it was found that late spring frosts in the province have the greatest impact on horticultural crops such as cherries, peaches, walnuts and grapes. As a result, early and late frosts changes in Semnan and Miami has increased, which in coming years will be also affected by this situation. Also, early frosts of autumn at harvest time and late spring frosts during flowering have many effects on crop yield. 

Assessment of the impacts of climate change on agro-climatic indices in Iran

Countries located in arid and semi-arid regions of the world, such as Iran, with highly dependent economy to agriculture, are more vulnerable to climate change. Six agro-climatic indices have been used, which include the length of the growing season and the frost-free season, dates of the occurrence of the last frost in spring and the first frost in autumn, and annual sum of the growing degree-days (GDD) for two temperature thresholds. To explore variabilities of the indices in the future, outputs of three regional climate models (RCMs) have been analyzed based on two Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios for the South Asia CORDEX region, with the horizontal resolution of 0.44°. Differences between the historical and future simulated agro-climatic indices have been calculated, in which the former is obtained from historical outputs of three models for the period 1961–1990, while the latter is based on future simulations during the period 2061–2090 applying RCP4.5 and RCP8.5 scenarios. Both RCP scenarios indicate an increase in the number of frost-free days (maximum 40 and 70 frost-free days according to the RCP4.5 and RCP8.5 scenarios, respectively), with higher changes in mountainous regions. Our results indicate that shorter frost days will be more common in northwestern and western Iran in the future period. The highest increase in annual sum of the GDD will be in southern and central Iran, but the lowest increase will be in northwestern Iran.