Влияние микроклиматических различий г. Арзамаса на фенологические процессы

The purpose of this work is to present the results of fi eld studies on the effectiveness of applying different primary tillage systems for soybean cultivation in the Forest-Steppe zone of Ukraine and the infl uence of agrometeorological conditions during the growing season on biological grain yield. Methods. The studies were conducted using four primary tillage systems: traditional (A1), conservative (A2), mulching (A3), and no-till (A4). Soybean cultivation technology in the experiments was traditional for the research area, except for the studied factors. The effectiveness of the tillage systems was determined by assessing the biological yield of soybean and its structure. Biological grain yield was determined from sample sheaves collected in triplicate for each variant. The main elements of yield structure for each variant were identifi ed during the analysis of the sample sheaves. Statistical data processing was performed using correlation analysis. Agrometeorological conditions during the soybean growing season were assessed using data from the Bila Tserkva weather station. Results. Among the studied primary tillage systems for soybean cultivation, the traditional system with plowing showed the highest biological grain yield. Replacing moldboard plowing (traditional system) and deep loosening (conservative system) with shallow tillage negatively affected the biological yield. The average biological soybean grain yield over the research years was 2.76 t/ha, ranging from a minimum of 1.82 t/ha (2018, no-till system) to a maximum of 3.88 t/ha (2021, traditional primary tillage system). During the research period, a signifi cant increase in average daily temperatures was observed in all summer months: June increased by 2.0 ºC, July by 1.1 ºC, and August by 2.0 ºC. Correlation analysis indicated that changes in average daily temperatures are refl ected in soybean biological grain yields. The strength of the relationship depends on the soybean growth and development phase and the primary tillage system used in the cultivation technology. Over the past ten years, the amount of atmospheric precipitation and its distribution have signifi cantly changed, especially in the summer months, as indicated by the trend line and comparison with actual data from the previous thirty years of observations: the average precipitation sum for June decreased by 23.2 mm, for July by 19.4 mm, and for August by 34.4 mm. Conclusions. The biological yield of soybean grain is related to the year’s conditions (r = 0.418) and the primary tillage system (r = 0.404): a decrease in tillage depth and the abandonment of moldboard plowing lead to a reduction in the biological grain yield formed by soybean phytocenoses. Changes in average daily temperatures are refl ected in soybean biological grain yields. The strength of the relationship depends on the soybean growth and development phase and the primary tillage system used in the cultivation technology. An increase in temperature in May (emergence – early branching phase) and August (grain fi lling – ripening phase) negatively affects the biological soybean grain yield, as evidenced by correlation coeffi cients of r = –0.370 and r = –0.303, respectively. There is a moderate direct correlation (r = 0.343) between biological yield and the average daily air temperature in June, and a weak direct correlation (r = 0.111) between biological soybean grain yield and the average daily air temperature in July. According to correlation analysis data, the amount of atmospheric precipitation during the vegetative development of soybean (May – June) practically does not affect the biological grain yield.

The relevance of this study lies in addressing a fundamental scientific issue-examining the dynamics of specific indicators of climate-dependent natural resources to ensure sustainable socio-economic development in Ukraine under global climate change conditions. The North-Western Black Sea region is a leading, highly developed industrial-agricultural area of the country, where information on its thermal regime is crucial, as it constitutes an essential component of natural resources. Given its potential for use in the southern regions of Ukraine, this research focuses on determining temperature indicators that will aid in planning and adapting various economic sectors in southern Ukraine amid regional climate transformations. The implementation directions of these objectives are formulated within the research projects of the departments of the Faculty of Hydrometeorology and Ecology at Odesa I.I. Mechnikov National University, including: 'Zoning of Ukraine's territory based on vulnerability to climate change and selection of optimal adaptation pathways.' (No. DR0125U001204). The underestimation of certain aspects of the dynamics of regional climate temperature characteristics in the context of global climate change has resulted in these aspects remaining insufficiently studied to date. Analysis of previous research it proves the importance of studying the climatic indicators of the temperature regime of the North-Western Black Sea region, which is a leading highly developed industrial-agricultural region of Ukraine. The underestimation of certain aspects of the dynamics of climatic characteristics of the regional climate in the context of global climate change has led to these aspects being still insufficiently studied today. This article aims (using the Odessa station as an example) to present the results of a physical-statistical approach to determining regional responses in the main indicators of the temperature regime of the North-Western Black Sea region to the changes occurring in the climate system of the present period. The implementation of the physical-statistical approach was conducted using classical methods of statistical and graphical analysis. Based on long-term empirical data for 1909 spring days of the period 2001-2023, the dynamics of interdaily variability of air temperature was analyzed and the number of days with average daily air temperature in different gradations was determined. Comparing the two periods of the 21st century, it was determined that in March from the first (2001-2010) to the second (2013-2023) the number of days with average daily air temperature in the range from 5.1 to 15.0°C increases sharply: from 43.2% to 62.1% of days; not a single case with a temperature above 15.0°C was recorded in the first decade of the 21st century, unlike the period 2013-2023; the number of days with an air temperature of zero degrees and below decreased by 2.3%. In April, in the period 2001-2023, the air temperature ranged from 5.1 to 15.0°C and accounted for 88.7%. In the last month of spring, the number of days with an average daily temperature in the range from 10.1°C to 20.0°C increased by 1.4%: from 84.8% to 86.2%, but the indicator with a temperature in the range of 20.1-25.0°C decreased by 0.3%. In April and May of the last decade, no cases with an air temperature of zero degrees and below were recorded. The frequency of the average daily air temperature in higher temperature ranges increased, which indicates warmer springs, compared to the 20th century. The obtained results provide a basis for analyzing the dynamics of regional climate changes in the context of global climate change. The rational and timely application of the climate information presented in this article will contribute to the development of effective adaptation pathways, which, in turn, will make a significant contribution to ensuring the sustainable development of Ukraine. Future tasks will focus on researching the thermal regime indicators of other stations in the North-Western Black Sea region, involving additional empirical data.

The article discusses the results of a statistical analysis of increases and decreases in the average daily air temperature, presented as waves of heat and cold. By a wave of heat (cold) we mean a change in the average daily air temperature by three degrees or more that lasted for at least two days. If a wave of heat (cold) was interrupted by one day of cooling (warming) or isothermy, such cases were considered a single wave. All waves were divided into dry and wet. A wave was considered wet if there was precipitation on at least one day during the development of this wave. We calculated the frequency of occurrence, duration of dry and wet waves, and the number of days with precipitation for each wave. The analysis was carried out for waves of different intensities. On average, the number of warm and cold waves per year is the same. Approximately the same number of warm and cold waves occur in winter and summer. In spring, heat waves prevail over cold waves, while in autumn the trend is opposite. The average duration of a wave is 4 days. The more intense the wave, the longer its duration. The majority of waves are wet. Precipitation accompanies 85% of heat waves and 75% of cold waves. Precipitation falls on about half the days of the wave’s duration. Cold waves are quite often interrupted by one-day increases in the average daily temperature. It is during these days that precipitation is observed. Synoptic analysis has shown that such cases of one-day ‘interruption’ of cold waves are associated with active processes of cyclogenesis on cold fronts. Wave formation at the cold front stimulates precipitation.

To determine the duration of interphase periods and the overall vegetation season of millet plants depending on the hydrothermal conditions observed during the research years. Methods. Field experiment, analytical method, mathematical and statistical analysis, comparative-calculation method. Results. It was demonstrated that the duration of the period from sowing to seedling emergence varied between 13 and 16 days depending on the prevailing weather conditions during the research years. This stage required an average daily air temperature of 15.8–18.9 °C and a sum of active temperatures above 10 °C ranging from 92.0 to 115.7 °C. The total vegetation period of the crop also varied across the years of study, ranging from 80 to 91 days. During this period, the average daily air temperature was 21.2–22.5 °C, the sum of active temperatures above 10 °C ranged from 998.1 to 1033.1 °C, and the amount of precipitation ranged from 120.2 to 203.2 mm. A strong inverse correlation was established between the duration of the sowing–emergence period and both the average daily air temperature and the sum of active temperatures (r = –0.959 and –0.877, respectively), while a strong positive correlation was observed with precipitation amount (r = 0.943). The duration of the vegetation period was strongly inversely correlated with average daily air temperature and precipitation (r = –0.990 and –0.698, respectively), and directly correlated with the sum of active temperatures above 10 °C (r = 0.924). Conclusions. The duration of the sowing-to-emergence period, as well as interphase periods and the entire vegetation season, was significantly influenced by weather conditions. Understanding the duration of these phases in relation to hydrothermal conditions enables better planning of millet sowing dates and associated agronomic practices aimed at creating optimal conditions for realizing the genetic potential of crop varieties.

The near-surface air temperature is an essential climatic variable wildly used in studies of meteorology, climate, and environmental health. Numerous studies have developed approaches to estimate near-surface air temperature from remote sensing data for clear sky conditions, but efforts to estimate air temperature for cloudy sky conditions and daily average air temperature using remote sensing data still few. The current study introduces an approach to estimate daily average near-surface air temperature using the estimated daily maximum and minimum air temperatures with the help of time series of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) observations. The daily maximum temperatures of clear sky pixels are estimated from three MODIS products data using a linear regression model as expressed in [1], and the AIRS standard surface air temperature products data are used to fill the cloudy sky pixels for the images after a downscaling process. The retrieved land surface temperatures (LST) from Aqua MODIS night-overpass observations are used as the daily minimum air temperatures for the clear sky pixels, and the cloudy sky pixels are also filled by AIRS standard surface air temperature products data. Thus, the daily average near-surface air temperature can be estimated according to the diurnal variation of near-surface air temperature. This method was validated using field observed air temperature data of 176 ground meteorological stations in August 2013. The mean absolute error (MAE) and the root mean square error (RMSE) are 1.2 °C and 1.6 °C. The strength of the proposed methodology is that it can obtain reasonable near-surface air temperature data from remote sensing data, so it is useful in regions with sparse ground stations.

Introduction. Improving methods for modeling and forecasting changes in the number of forest fires, as well as the frequency of thunderstorms that cause them, is a significant challenge for environmental safety, emergency preparedness, and climatology. This is particularly relevant for regions with a forest landscape, such as the KhantyMansi Autonomous Okrug (Yugra). Domestic and foreign researchers have found that variations in seasonal average air temperatures and solar activity are effective predictors for modeling these processes in many regions. However, the connections between these processes and these factors in Yugra remain understudied, hindering our ability to determine the usefulness of including them in predictive models. The aim of the study is to test the hypothesis that there are significant statistical relationships between changes in the frequency of thunderstorms, the number of forest fires in the territory of Yugra, and variations in average air temperatures near the surface of the atmosphere during the thunderstorm season. The study aims to investigate whether these relationships are significant and increasing during periods of climate warming, as well as to assess the impact of solar activity on these relationships. To achieve this goal, we have analyzed the significance of correlation between the changes in the frequency of thunderstorms over the territory of Ugra and synchronous variations in the number of forest fires occurring here, as well as synchronous and ahead of time variations in the average seasonal air temperatures and solar activity in the period of climate warming. Materials and Methods. The study used observational data on average daily air temperatures, dates of thunderstorms over representative hydrometeorological stations of the studied area, information on changes in average annual solar radiation with a wavelength of 10.7 cm, and information on forest fires and related emergencies in Yugra. The data were obtained from international and Russian climate data banks and systems, as well as official reports from relevant ministries and agencies. The method of assessing the strength of links between processes was multiple correlation analysis. The statistical significance of identified links was assessed using the Student's t-test.Results. As a result of the study, it was established that the hypothesis put forward was valid. There was the correlation between the changes in the frequency of thunderstorms and the number of forest fires in the territory of Yugra with variations in average air temperatures and solar activity during the thunderstorm season. This trend was significant and increasing. We proved that the correlation of interannual changes in the number of forest fires that occurred in the XXI century in the territory of Yugra per year with synchronous variations in the frequency of thunderstorms over it was significant and intensified. The conditions were identified under which statistical relationships between changes in the frequency of thunderstorms here, as well as variations in average monthly air temperatures and solar activity, were significant and are increasing now. Therefore, when these conditions were met, it was advisable to take into account the factors under consideration during modeling and forecasting of the process under study. Discussion and Conclusion. The results obtained fully confirm the existing ideas about the impact of climate change and solar activity on the frequency of thunderstorms in the atmosphere, as well as the features of current climate change in Western Siberia. These connections can be used to predict changes in thunderstorm frequency and forest fire risk, and these predictions should be taken into account when planning activities within the unified state emergency management system.

Sheep are animals whose reproduction is affected by environmental conditions, and knowledge of the dependence of reproduction on climatic parameters will help to adjust the conditions of animal keeping. The purpose of the research was to investigate a correlation between the reproduction rates of Ascanian Merino ewes with such climatic factors as air temperature and humidity and the THI (temperature-humidity index). 3070 data of adult and 1.5-year-old ewes obtained during 2011–2022 were analysed. Methods of variational statistics and correlation analysis were applied. The degree of correlation was determined by the z-value (adjusted r-coefficient). The results showed that the fertility F% and fecundity Fm% had a strong negative correlation with the average daily air temperature in June — z = −0.996 (P<0.05) and −0.951 (P<0.05) respectively and a moderate one with the temperature in June–July −0.776 (P>0.05) and −0.887 (P<0.05), and the prolificacy Pf had a moderate negative correlation with the average daily air temperature in July −0.633 (P>0.05) and a strong one with the temperature in July–August −0.887 (P<0.05). The indices of the sexual activity renewal — index of heat IHi, index of heat time IHTi and index of conception time ICTi — revealed a significant relationship at the level of a moderate–strong with the average daily air temperature in June 0.929 (P<0.05), 0.741 (P>0.05), 0.829 (P<0.05), respectively, which indicates a decrease in the proportion of animals with the manifestation of sexual heat and a delay of the time of the manifestation of first sexual heat and conception with an increase in the temperature in June. The dependence of reproduction rates and indices of renewal on air humidity did not exceed the level of moderate, and the relationship with the THI mainly repeated the nature of the correlation with temperature. It was concluded that the reproduction rates of ewes of the Ascanian Merino breed at a moderate–strong level correlate with the temperature factors. Indicators related to the manifestation and time of heat show a greater level of correlation with the temperature in June, prolificacy — with the July parameter.

The research was carried out on the basis of the VNIISPK Laboratory of Fruit Plant Resistance Physiology in 2019-2020. The research object was the Novella cherry variety on the clonal rootstocks of the institute selection. The purpose of this research is to study the dynamics of the water regime of the Novella variety on clonal rootstocks and to identify the most adapted scion-rootstock cherry combinations. A strong relationship was determined between the cherry leaves hydration and the average daily air temperature (r = 0.99). During the ripening period of the fruits of the Novella variety scion-rootstock combinations, the maximum decrease in the total water in the leaves was recorded. The water content decreased as the age of the leaves increased. The decrease in water content in the Novella scion-rootstock combinations was accompanied by an increase in the dry matter content in the leaf tissues. There was a strong relationship between the dry matter accumulation in the leaves and the average daily air temperature (r = -0.99). The water deficit in the leaves depended on the hydrothermal regime of the summer period. Correlation (r = 0.76) between the leaves water deficit and the average daily air temperature, the amount of precipitation (r = -0.77) and the HTC (r = -0.83). The highest water deficiency indicator in leaves was found during shoots growth and formation of the leaf apparatus in the Novella variety on clonal rootstocks. The conducted studies allowed to identify adapted scion-rootstock combinations of Novella/Rubin, V-2-180, 74340, 74336, 74332, which, against the background of water content decrease and dry matter accumulation were characterized by the lowest water deficit of leaves in the summer.

From 2011 to 2024, a long-term multifactorial experiment was conducted on the slope of the Bolshoy Log ravine in the Aksai district of the Rostov region. Various crop rotations, fertilizer application levels, and methods of primary soil treatment were studied. The research aimed to determine the optimal combination of hydrothermal factors (average daily air temperature, total precipitation) for obtaining high and stable sunflower yields in the conditions of the Azov district of the Rostov region. The research revealed an increase in air temperature during the sunflower growing season with a simultaneous decrease in precipitation. Depending on the fertilizer application rate, sunflower yield ranged from 1.44 to 2.21 t/ha. A slight effect of precipitation on sunflower yield and a strong negative effect of average daily air temperature were identified. The optimal conditions for obtaining high sunflower yield in the Azov district were determined to be an average daily temperature of no more than 22.0 °C and more than 300 mm of precipitation during the growing season. Increasing the fertilizer application rate provides a cost recovery in the form of an increased yield of 4.5–6.0 kg of seeds/kg of active ingredient when the average daily air temperature increases to 23.5 °C and the amount of precipitation decreases to 160 mm during the growing season.

Wine contamination by ochratoxin A in relation to vine environment

Winter wheat is the main grain crop in Ukraine, but in recent years its yields have been declining and grain quality has been deteriorating. A significant amount of winter wheat grain does not meet the requirements for food grain, which in turn affects the quality of flour and bread. The main factor for obtaining highly productive winter wheat crops is to improve their structure, which depends on the sowing time, seeding rate, field germination of seeds, plant survival in winter, etc. The yield and quality of winter wheat seeds are formed during the period of their cultivation, where both the genetic potential of the variety and soil, climatic and agronomic conditions play an important role [4]. Therefore, creating favourable conditions for high field germination of seeds is one of the priority tasks in growing grain crops. The aim of the study is to determine the influence of weather factors on the field germination of winter wheat seeds. The research programme envisages determining the impact of weather conditions - average daily temperatures, the sum of active temperatures, precipitation during sowing and germination, and productive soil moisture reserves at a depth of 0-10 cm - on the field germination of winter wheat seeds. Laboratory and field studies were conducted at the experimental farm of the Institute of Plant Physiology and Genetics during 2016-2020. Varieties of different maturity groups - medium early and medium early - were used for the study. Field germination was calculated as the ratio of the number of seedlings to the total number of sown germinating seeds. Studies of the influence of weather conditions on the field germination of winter wheat seeds have shown that in 2016 the temperature regime of this period was lower, the sum of active temperatures was 117,5 ºC, the average daily temperature was 11,8 ºC, and the amount of precipitation for three decades was only 5,4 mm, with a moisture deficit of 88,0%. Such conditions did not contribute to the accumulation of productive soil moisture and its preservation, which led to a decrease in the percentage of field germination of seeds to 76%. With a high sum of active temperatures during the third decade of September 2017 of 141,1 oC and 2,2 mm less precipitation in September, the productive moisture content of the sowing soil layer (0-10 cm) was 23 mm, which is below the optimal level (30 mm), and the average field germination rate of the varieties' seeds was 77%. The period of sowing and germination in 2018 was characterised by sufficient moisture supply, with precipitation at the level of the long-term average of 57,7 mm (36,5 mm in the first decade and 21,2 mm in September), which was 28,2% higher than the long-term average, and productive soil moisture of 34 mm, which ensured field germination at 82%. The periods of sowing and germination in 2019 and 2020 were also favourable for seed germination. The average daily air temperature, which was at the level of the long-term average in 2019 and 2,8 °C higher than the long-term average in 2020, and sufficient precipitation, which contributed to the accumulation of productive moisture in the soil (37 mm in 2019 and 35 mm in 2020, which is 7-5 mm more than optimal), ensured field germination of seeds at the level of 86% and 83%, respectively. The study of the influence of varietal characteristics on the field germination of seeds revealed that with almost the same laboratory germination of sown seeds, there was no significant difference between varieties in field germination of both medium early and medium early varieties. On average, for medium-early ripening varieties, the field germination of seeds over five years was 81% with variation by variety from 80 to 82%, and for medium-ripening varieties also 81% with variation by variety from 80 to 83%. Over the years of research, there was also no significant difference in field germination of seeds depending on varietal characteristics, it changed only depending on weather conditions during sowing and germination.

The purpose of the work was to establish regularities of the ice formation in the largest European Lake Ladoga depending on the air temperature. The average daily air temperatures obtained at the Sortavala weather station for thirty years were used for the analysis. The main task was to determine the sums of accumulated average daily air temperatures necessary for the appearance of primary ice phenomena in areas with different depths of the Lake. To solve this problem digitized remote sensing data of the spatial distribution of ice in the fixed cells with known average depth and data on average daily air temperatures were used. For thirty last winters, the dates of the first ice appearance in each of 180 cells were selected, which were related to the accumulated to this date sum of mean daily air temperatures after its steady transition through 0°С towards the negative values. The resulting scheme of the accumulated sums of air temperatures needed for the ice appearance indicates their regular growth with increasing depth. It is assumed that this dependence will make it possible to assess dynamics of ice formation on other lakes.

Aim. To investigate the impact of weather conditions in the Forest-Steppe of Ukraine and genetic specificities of cultivars on the content of vitamin C, polyphenols, flavonoids, and anthocyanins in strawberry fruits. Methods. The study was conducted in 2023–2025; strawberry fruits of 7 cultivars of different ripening periods were selected in the experimental plots of the Institute of Horticulture of the NAAS of Ukraine. The weather indices of the vegetation period prior to collecting strawberry fruits were taken from the meteorological station Vantage Pro2 Plus, located in the experimental plots of the strawberry. The analytical study was conducted by the method of determining the quality of fruit and berry products (Kondratenko et al., 2008), in particular, using spectrophotometry methods, the content of biologically active substances was determined and expressed in mg/100 g FW. The amount of vitamin C was determined using titration with the solution of 2,6-dichlorophenolindophenol, the content of polyphenolic substances was determined using the Folin-Denis reagent, the content of flavonoids by measuring the absorption of the complex of flavonoids by aluminum chloride in the ethanol medium, the content of anthocyanins by the difference method in two buffer systems: with potassium chloride, pH 1.0 (0.025 M) and sodium acetate, pH 4.5 (0.4 M). The statistical analysis of the study data was conducted in STATISTICA 13/1 (StatSoft, Inc., USA). Results. The weather indices of the period of growth and development of strawberry fruits had a considerable impact on the content of vitamin C, polyphenols, flavonoids, and anthocyanins in them. The content of vitamin C in the fruits of cultivar Herkules was the most stable and independent from weather conditions of the cultivation year, with a minimum of 50.4, a maximum of 57.6, and an average of 53.5 mg/100 g FW. The content of vitamin C in strawberry cultivars Florence and Vibrant was the most variable and dependent on the weather conditions of the cultivation year, the average content was 52.0 and 50.9 mg/100 g FW. The amount of vitamin C in strawberry fruits considerably depended on the average daily air temperatures; the correlation coefficients for the investigated group of cultivars were high, over 0.720, the increase in the average daily air temperatures promoted a decrease in the content of vitamin C. The amount of polyphenols in cultivars Herkules and Prezent had a significant correlation with the average daily air temperatures and the HTI for the period of their growth and development, but in the first case, the correlation was direct, and in the second one, indirect. Among the investigated cultivars, the fruits of cultivars Veselka, Vibrant, and Florence were capable of accumulating the maximal amount of flavonoids, over 70 mg/100 g FW. The fruits of Prezent cultivar were capable of accumulating more than 20 mg/100 g FW of anthocyanins. The content of flavonoids in Prezent cultivar and that of anthocyanins in Veselka cultivar was homeostatic. Conclusions. It was determined that the content of biologically active substances in strawberry fruits was determined by genetic specificities of the cultivar and corrected by weather conditions for the period of their growth and development.

The subject of the study was the conditions of formation of high-protein winter wheat grain. The main goal of the research was to identify the relationships between the main agrotechnical practices, weather conditions in the early spring and protein content in winter wheat grain and to create methodological foundations for the development, implementation and adjustment of ecologically adaptive technologies for growing winter wheat in the northern Steppe of Ukraine. The research was conducted during 1986-2005 at Kirovohrad State Agricultural Experimental Station. The winter wheat was sown in three terms on 25 August, 17 September and 2 October after black fallow and non-fallow maize silage predecessor. The protein content of the grain was determined by conventional methods. The soils of the experimental plot are ordinary medium-humus heavy loamy deep chernozems. It has been substantiated that in the northern Steppe of Ukraine, winter wheat under black fallow provides a higher protein content in grain compared to its non-fallow predecessor. During the years of research, the protein content in the grain of winter wheat under black fallow was 13.94 compared to 13.0% after corn for silage. After both predecessors, both high and low amounts of protein can be accumulated in winter wheat grain at high yields. Shifting the sowing dates of winter wheat from 25 August to 2 October for black fallow, on average over the years of research, causes a decrease in the protein content of grain from 14.2 to 13.7%, and for corn for silage, on the contrary, an increase from 12.9 to 13.1%. However, this dependence can be clearly seen in 74% of years under black fallow and 47% of years after the non-fallow predecessor. In the conditions of the northern Steppe of Ukraine, the time of renewal of the spring vegetation of winter wheat plants affects the protein content of its grain. The average (third decade of March) time of spring vegetation recovery of winter wheat plants contributes to a higher protein content in the grain, which is 14.2% after black fallow and 13.37% after corn for silage. In years with an extra-early (third decade of February) renewal of spring vegetation, the lowest amount of protein is accumulated in winter wheat grain after both predecessors. The nature of the air temperature regime in the early spring period determines the protein content of winter wheat grain. When winter wheat is placed on black fallow, the highest protein content in winter wheat grain is observed in years when the average daily air temperature passes through 00C in the third decade of February and is 14.45%, and after the non-fallow predecessor – in the first decade of March – 14.16%. The highest amount of protein in winter wheat grain after both predecessors is accumulated in the years with a period from the time of transition of the average daily air temperature through 00C to active vegetation of plants from 20 to 30 days and after black fallow is 14.57%, and after non-fallow predecessor – 13.35%. In the years with the duration of this period exceeding 30 days, grain with the lowest amount of protein is formed. A sharp decrease in the protein content of winter wheat grain in the northern Steppe of Ukraine is observed in the years with an average daily air temperature during the period of ‘spring vegetation renewal – heading out’ above 110C. After black fallow, the protein content of grain decreases from 15.0 to 13.0%, and after corn for silage – from 14.3 to 13.3%. An increase in the duration of the period ‘restoration of spring vegetation – heading out’ increases the protein content in winter wheat grain. In the years with the duration of this period exceeding 35 days, the amount of protein in winter wheat grain for black fallow increases by 1.7%, and in corn for silage by 0.8% compared to the years with duration of this period not exceeding 25 days.

Sample size for estimation of the plastochron in pigeonpea