Productivity and economic efficiency of growing sunflower depending on the sowing time and plant density in the Right-Bank Steppe of Ukraine

Abstract. The article presents the results of scientific researches on the influence of sowing time and density of standing of sunflower plants on the dynamics of the content of available moisture in soil in the conditions of the Right-bank Steppe of Ukraine.
 One of the decisive factors for the achievement of high and sustainable crop yields in the conditions of unstable moistening of the Right-Bank Steppe of Ukraine is the accumulation and rational use of moisture, which is one of the most important unregulated factors limiting the yield.
 On average, during the years of research, the most available moisture in the 0-10 cm soil layer was in the first sowing period - when it was heated to a depth of seed 5 - 60C and was 25.0 mm. It was found that the moisture available to plants in the meter layer of soil at the time of sowing remained high and significantly influenced the dynamics of emergence of seedlings. On average, during the years of research, the most available moisture in the 0-100 cm soil layer was during the first sowing period - for warming it to a depth of seed 5 - 60C - 178.6 mm. In such conditions, quite favorable conditions of moistening of the sowing layer of soil are created in order to receive friendly and complete seedlings when sowing in the first - second decade of April. However, at the end of the third decade of April, there is a significant decrease in gross moisture reserves in the sowing and deeper layers of soil, which limits the productivity of crops.
 Of particular importance for sunflower plants is the content of available moisture in the 0 - 100 cm layer of soil after the formation of baskets. During this period, the sunflower intensively consumes the available moisture from the deeper layers of soil. Analyzing the results of the research, it should be noted that in most cases, a higher seed yield in sunflower hybrids was formed in those variants where the period from the formation of the basket to flowering occurred in June or the first decade of July, regardless of the year of fall medium long-term indicators.
 It was also found that the moisture available to plants in the meter layer of soil in the flowering phase was different during the years of research and varied in terms of sowing and depended on the density of plants. The highest moisture reserves available to the plants in the soil layer were 0-100 cm, in the crops of Forward hybrids, LG 56.32, LG 54.85, LG 55.82 were at planting densities of 60 thousand hectares, at the first sowing period - in the flowering phase - 127 mm. 
 The optimal sunflower sowing period for LG 55.82 and LG 54.85 hybrids in the Right Bank steppe is soil warming up to a depth of seed 5-60C, for Forward and LG 56.32 hybrids is warming up to, a depth of seed 9-100C, optimal density - 60 thousand on ha. Under these conditions, the LG 55.82 hybrid produced a yield of 3.85 t / ha, the LG hybrid 54.85 - 3.64 t / ha, the Forward - 3.09 t / ha, the LG hybrid 56.32 - 3.62 t / ha.
 Taking into account the annual variation of weather conditions of spring sowing, it should be differentiated with regard to water and heat regimes.
 

The article presents the results of scientific research on the management of technology elements and the influence of factors on the productivity of sunflower in the Right-Bank Steppe of Ukraine. The studies were conducted in the fields of the Institute of Agriculture of the Steppe NAAS, which is located in the black earth zone of the Right-Bank Steppe of Ukraine. The level of sunflower productivity is determined by the conditions of water and nutrient conditions of soil. Water regime is formed by the weather conditions, the amount of soil moisture reserves, the amount and intensity of rainfall during the year, incl. during the growing season. The moisture reserves available to plants in the meter layer of soil before sowing, in the flowering phase and before harvesting were different during the years of research, varied in terms of sowing and depended on the density of standing plants. Of particular importance for sunflower plants is the content of available moisture in the 0–100 сm layer of soil after the formation of baskets. During this period, sunflower intensively consumes available moisture from deeper layers of soil. The amount of nitrogen, phosphorus and potassium varied significantly over the years and under the influence of different fertilizer backgrounds. Application of nitrogen fertilizers in combination with phosphorus and potassium, N40P40K40 + PP and N40P40K40, improves soil nutrition and creates more favourable conditions for growing and developing sunflower plants and maintaining soil fertility. Under these conditions, the LG 55.82 hybrid with a plant density of 60 housand/ha formed the highest yield for the first sowing period – 3.85 t/ha. Considering the economic indicators, it is efficient to grow LG 54.85 and LG 55.82 hybrids for the first sowing period. Forward and LG 56.32 sunflower hybrids provide the highest economic performance for the third sowing period. Among the hybrids, it is most economically apropriate to grow LG 55.82 when sowing at soil temperature of 5–6°C and plant density of 60 thousand/ha. The net profit in this variant was 22043 UAH/ha, and the level of profitability was 224.1%. The energy efficiency ratio was the highest in the first sowing period of the LG 55.82 hybrid – 4.44.

The relevance of the current study is due to the fact that global warming in the south of Russia has significantly moved forward the onset of the hot period, especially in areas of risky farming. Sowing at the previously recommended scientifically based optimal time no longer guarantees stable yields of maize. Based on this, the purpose of the study was to determine the effect of the sowing time of new promising maize hybrids of our own breeding on productivity and yield structure elements in the steppe part of Kabardino-Balkaria. The study was carried out in field trials on the field of the research and production site of the Institute of Agriculture of the KBRC of the Russian Academy of Sciences in 2019–2021. In general, during the years of study, weather conditions were typical for the steppe area of the KBR. As a result, there was determined that the optimal sowing time for maize hybrids was the second decade of April. When sowing at this time, there was identified productivity improvement and an increase in the values of yield elements. On the contrary, sowing in the third decade has shown a decrease in the values of these indicators in all studied samples. During the second sowing period, there was the greatest productivity decrease among the late-maturing hybrids ‘Karat SV’, ‘Terek’ and the hybrid population ‘Kabardinskaya 3812’ by 1.4; 1.5 and 1.8 t/ha, respectively. The middle-early hybrid ‘Maisky 260 MV’ has shown a smaller decrease by 0.7 t/ha. During the first sowing period, number of ears per 100 plants increased by 4–11 pieces. The ears were better grained with 5–60 pieces of the excess over the second period. The weight of one cob during the first sowing period ranged 105–120 g on average, which was 9–22 g more than the same indicator during the second sowing period.

Purpose: to develop rational combinations of species and varieties of perennial leguminous grasses, soil water and nutrient regimes, which will contribute to obtaining stable fodder yields with high levels of protein and energy content. Materials and methods. Research is being carried out on perennial leguminous grasses on the experimental field of the institute. The experiment is three-factor and includes three options for maintaining the pre-irrigation soil moisture limit (60, 70 and 80 % of the lowest moisture capacity), three options for the soil nutritional regime (NPK₁, NPK₂ and control – without fertilizers), eight types of legumes are studied according to the third factor. The generally accepted experimental methods were used when setting up experiments and conducting research. Results. In the full germination phase there were from 294 to 386 plants of grass species per 1 sq. m. Their height before harvesting varied according to the experimental variants from 0.60 to 1.01 m in the first cutting, from 0.38 to 0.94 m in the second and from 0.25 to 0.66 m in the third cutting. The grass stand total water consumption in the year of seeding was 4.2–4.7 thous. cub. m/ha, increasing in subsequent years to 4.8–5.7 thous. cub. m/ha. The soil water regime and fertilizers had a significant impact on crop yield. In control options with a pre-irrigation limit of 60 % of the lowest moisture capacity, the green mass yield in the second year was 26.6–40.9 t/ha. With improved soil nutrition and good water supply, the yield increased to 48.2–87.8 t/ha. Sainfoin and blue-hybrid and variegated alfalfa plants responded to the improved growing conditions most actively; 54–88 t/ha of green mass were gathered from these sites during the season. Conclusions. Selection of optimal combinations of soil water and nutrient regimes, as well as the new promising perennial leguminous grasses species and varieties introduction into the field feed production in the Lower Volga region will ensure high and stable yields of fodder rich in energy and nutrients.

The Crimean Peninsula is located in the dry zone. In the steppe Crimea, which is the driest part of the peninsula, the major limiting factor for crop productivity is the natural moisture supply of plants. The purpose of the research was to establish the relationships between hydrometeorological factors (moisture reserves in the soil before sowing, precipitation amount and Selyaninov hydrothermal coefficient during the growing season) and sunflower yield depending on planting dates (I, II, III decade of April) and plant density (30, 40, 50, 60, 70 thousand units per hectare). The studies were carried out on the trial fields of the Research Institute of Agriculture of Crimea (village of Klepinino) in 2017–2019 using hybrid of ultra-early sunflower ‘Avangard’. The laying of field experiments, accounting, analyzes and statistical processing of data were carried out according to the methods of field research and methodology of field agricultural experiments with oil crops. A strong correlation was observed: 1) between yield and precipitation amount in May (r = 0.977) and moisture reserves before sowing (r = 0.978), planting dates – the first decade of April; 2) between precipitation amount in May (r = 0.932) and moisture reserves before sowing (r = 0.977–0.978), sunflower was sown in the second decade of April; 3) moisture before sowing (r = 0.892), crop planted in the third decade of April. A close positive relationship (r = 0.853–0.972) was observed at the optimal plant density for the region (40 thousand units/ha) between the amount of precipitation in April–May, moisture reserves in the soil before sowing and yield of sunflower. This indicates a high value of moisture availability during this period in the crop yield formation. In denser crops (50–70 thousand units/ha), the closest relationship is observed between the yield and the amount of precipitation in May. This makes the latter primary and decisive in the cultivation of crops with such a density since the competition for moisture increases with an increase in the number of plants per unit area. The closest relationship between the Selyaninov hydrothermal coefficient and sunflower yield was observed in April and May (r = 0.833–0.967) when plants grow more intensively and require sufficient moisture.

Influence of Sowing Times and Agricultural Plant Care on Water Consumption and Productivity of Sunflower Hybrid Region

Abstract. Purpose. The study is aimed at a comparative analysis of apricot cultivars of various ecological and geographical origin of the genetic collection of the Mountain Botanical Garden by the initial phenological phases of flowering and vegetation in order to determine their degree of interconnection and determine the autochthonous varieties and forms of the Dagestan apricot. Methods. The study is based on the methods of phenological observations in accordance with generally accepted methods with their own additions. Results. It was revealed that the appearance of red bud varieties varied in a wide range (March 28 – April 21), on average, on April 6. The white bud phase was observed in the first and second decade of April from the 1st to the 25th day of the month, and the beginning of flowering from April 5 to 28. Vegetative buds begin to wake up as a whole later than generative ones, with the exception of varieties and hybrids bred from crosses with plum and alpine plum. Beginning swelling buds, flushing buds and leaves in the second and third decade of April, on average on April 11, 21 and 25, respectively. Correlation analysis showed the presence of a positive correlation between the majority of generative and vegetative traits of varieties and forms of apricot, significant at the level of P ≤ 0,05. An inaccurate correlation was found between the trait “bud swelling” and all generative traits. According to the results of cluster analysis, the proximity of most of the cultivars of Dagestan origin to each other was established, with the exception of the Khonobakh variety and its varieties, which turned out to be closer to the Central Asian varieties, which is probably due to its allochthonous origin. The scientific novelty of the study is to assess the phenological phases of flowering and swelling of apricot cultivar leaves under the conditions of the Tsudakhar experimental base showed that the majority of Dagestan cultivars are early flowering (13 samples from 22) and medium (7), while in European and Central Asian prevail varieties of medium and late flowering.

In the years 2008-2011, phenological observations of flowering of male inflorescences were carried out in seven taxa from the genus <em>Corylus</em>: <em>C</em><em>. americana</em>, <em>C</em><em>. avellana</em>, <em>C</em><em>. avellana</em> ‘Contorta’, <em>C. avellana </em>‘Pendula’, <em>C. </em>× <em>colurnoide</em><em>s</em>, <em>C</em><em>. cornuta</em>, <em>C. maxima</em>, grown in the Maria Curie-Skłodowska University Botanical Garden in Lublin. Simultaneously, the hazel pollen seasons in the atmosphere of Lublin were analysed using a Durham sampler. The aim of the work was to assess the flowering in seven <em>Corylu</em><em>s </em>taxa in relation to selected meteorological elements and to describe the pollen seasons in the years 2008-2011.<br /> During the study years, the annual phenological cycles in the studied <em>Corylus </em>taxa differed markedly in terms of timing of the onset of the successive flowering phases. During the four years of observations, the earliest beginning of hazel flowering was found at the end of January, whereas the latest – at the end of March. The earliest full bloom took place in the first decade of February, and the latest – in the first decade of April. The end of flowering was reported in February or in the first or second decade of April. Each year, <em>C. avellana </em>was the first to produce flowers and it was subsequently followed by <em>C. americana</em>, <em>C. </em>× <em>colurnoides</em>, <em>C. maxima</em>, <em>C. avellana </em>‘Pendula’, <em>C. avellana</em> ‘Contorta’, and <em>C. cornuta</em>. The pollen seasons in the study period began at the end of January, in the second decade of February, or in the first decade of March. The end of the pollen seasons most frequently took place in the first or second decade of April. The length of the pollen seasons ranged from 38 to 49 days, while the length of the flowering periods in the individual taxa was 22 days on average. During the four study years, the onset of flowering in <em>C. avellana </em>and the beginning of the pollen season coincided on the same day, whereas the onset of flowering in the other taxa was usually reported after the beginning of the pollen seasons. The flowering period of <em>C</em>. <em>avellana </em>‘Contorta’ and <em>C. cornuta </em>lasted from 5 to 16 days after the pollen season. The development of inflorescences was most closely related to maximum temperature and relative air humidity.

This study, conducted in the period 2006-2008, involved an evaluation of yield and commercially useful traits of red cabbage grown from seedlings produced from seeds sown at three different times (the second decade of April, the third decade of April, and the first decade of May). Seedlings were produced in multicell trays in an unheated greenhouse and in a nursery bed from seeds sown at the same time. The experiment included 6 red cabbage cultivars (‘Huzaro F<sub>1</sub>’, ‘Kalibos’, ‘Langedijker Polana’, ‘Rodeo F<sub>1</sub>’, ‘Roxy F<sub>1</sub>’, ‘Zelox F<sub>1</sub>’). After cabbage heads were harvested in the second decade of October (in each year), total and marketable yield as well as head weight and the head shape index were determined. Red cabbage yield was shown to be significantly dependent on the cultivar, time of sowing, and method of seedling production. Among the cultivars studied, the following proved to be the most productive, irrespective of the other experimental factors: ‘Zelox F<sub>1</sub>’ (marketable yield averaged 398.11 kg×100 m<sup>-2</sup>), ‘Roxy F<sub>1</sub>’ (marketable yield averaged 368.82 kg×100 m<sup>-2</sup>), and ‘Rodeo F<sub>1</sub>’ (marketable yield averaged 331.59 kg×100 m<sup>-2</sup>). The cultivar ‘Kalibos’ was characterized by the lowest marketable yield (on average 257.09 kg×100 m<sup>-2</sup>). Delayed sowing (to produce seedlings) by 10 and 20 days, compared to the earliest sowing time, had a significant effect on the reduction in total and marketable yield. Irrespective of the time of sowing, the production of seedlings in multicell trays did not have a significant effect on higher head weight. But the influence of the cultivar was significant - heads of the highest weight were found in the yield of the cultivar ‘Zelox F<sub>1</sub>’ (head weight was on average 1.71 kg). The head shape index was more than 1 and on average it did not exceed 1.35. The cultivar ‘Kalibos’ had the most elongated heads (with a conical shape), while cabbage heads in the cultivar ‘Langedijker Polana’ were closest to the spherical shape.

Rising temperatures are already affecting fruit production, and phenological data are important in examining the agroclimatic conditions of the area. The research aims to analyse climate indicators for the sustainability of apple (Malus domestica, L.) production in Slovakia – the onset of the phenological phase of full flowering (BBCH 65) in 1931–2020, the occurrence of frost days in 1961–2020, and the analysis of the area and yield of apple trees in 2014–2022. The results show that in 1931–1960, full flowering began in the third decade of April (western Slovakia – April 24) and in the first decade of May (eastern Slovakia – May 3). On the contrary, over the past 30 years, the average onset begins already in the second decade of April (western Slovakia – April 18) and in the last decade of April (eastern Slovakia – April 25). This also caused a higher probability of frosts occurring between the 1st and 10th day after the onset of the BBCH 65 phase (Piešťany station – up to 137%), and thus a greater risk of flower damage. Due to climatic and economic factors, the total area of orchards is decreasing, but this is also related to the decrease in fruit harvest in Slovakia.

In order to study the effect of the time of sowing seeds on the passage of morphogenesis and productivity of rapeseed, the scheme included experiments where the seeds were sown in I, II, III in April, I and II in May. The experiment used varieties of Golden Ball, Purpurleopop, Purpurov and Geisha, and control was the variant in which the seeds of the Golden Ball varieties were sown in the second decade of April with a row spacing of 45 cm. laboratory - to determine the total yield; statistical - to establish the reliability of the investigated factors. Seed germination analysis used in the experiment ranged from 78.9% to 81.1% on average. The highest indicator of seed germination was characterized by the Purpulepop variety, where the studied value was 83.2%, which was dominated by the seed germination of the control variant by 2.1%. In the early stages of sowing seeds, the period of seedling formation was shorter. Seeding of seeds in the first two decades of April on the surface of the soil was observed for 8 days. The short sprouting period was characterized by all varieties of turnips. As a result of sowing turnip seeds at a later date, namely in the third decade of April - the first and second decade of May and the setting of a higher soil temperature, the period of germination was extended and ranged from 8 to 10 days. By using the term of sowing seeds I-II decade of April, the short interphase period was characterized by Purpleupop and Purpurova varieties, where the specified period was only 22 days. The sowing of turnip seeds at a later date ensured the formation of an interphase period of "seedlings - leaf rosette" in 23-25 days except Purpulopop variety. The interphase period "leaf rosette - the beginning of rooting" and "the beginning of rooting - technical maturity" determined the benefits of early seeding, namely in the first decade of April on varieties Purpulopop and Purpurov.The short vegetation period was characterized by the Golden Ball plants for sowing seeds in the first and third decades of April and the first of May. During the specified seeding period the duration of the growing season was only 40 days. A longer vegetation period was characterized by plants of the Geisha variety for sowing seeds in the first two decades of April. As a result of the use of the researched elements of technology to grow turnips in open soil, the total yield varied from 11.0 t / ha to 24.0 t / ha. The most productive is the first sowing of rapeseed, where its value ranged from 20.6 t / ha to 22.7 t / ha. At the same time, when sowing seeds in the first decade of April, the yield of turnip varieties Purpulepop was the highest and was 22.7 t / ha, or the increase was 2.4 t / ha.

Relevance of the research. Winter wheat is considered to be a leading cereal crop. One of the area of stabilizing this crop production is to intensify its cultivation on the drained soils of Polissya. Due to the changes in external factors (global and regional climate change, soils, etc.) and technology, the question of modeling the process of crop productivity formation remains relevant. Objective of the research was to evaluate the impact of climate change (increase of average air temperature) on the winter wheat yield on the drained lands of Western Polissya when applying different fertilizer systems. Research methodology. The research was conducted in a stationary long-term field experiment of the Volyn State Agricultural Research Station of NAAS. The following fertilizer systems were investigated: control (without fertilizers); organic fertilizer – green manure crop; mineral fertilizer - N60P60K60 + lime; organic-mineral fertilizer - N60P60K60 + green manure crop + lime. In the course of the study, a systematic analysis of long-term results of field experiments and meteorological observations using mathematical and statistical methods, correlation and regression analysis were used. Research results. The coefficient of yield variation over the years of research on a variant without fertilizers reached 27%, against 19% for the organic-mineral fertilizer system. Applying the fertilizers helped to reduce the variability of winter wheat yield by 19 - 23%. Correlation analysis of winter wheat yields in view of the average air temperature of the early spring period (from the second decade of February to the first decade of April) was 0.85. Low air temperatures in this period indicate the late dates of the beginning of spring crop vegetation, which negatively affected wheat productivity. Relatively high temperatures contribute to earlier spring processes and, accordingly, positively affected the yield formation. The correlation coefficient of the average air temperature and wheat yield in the spring-summer period (second decade of April - the second decade of July) was - 0.71. Conclusions. The highest efficiency on sod-podzoliс drained soils is provided by applying organic-mineral fertilizer system. The average wheat grain yield when applying this fertilizer system was 5,7 ton per hectare (+ 38% over control). The application of balanced fertilizer systems reduces the amplitude of grain yield fluctuations from 27% to 19%. The temperature regime in the period from the 2nd decade of February – till the 1t decade of April has a significant effect on the yield of winter wheat grains. Having the average temperatures over 5оC, yields increased by 1-1,5 ton per hectare, and on the contrary, rise of average temperatures in the spring-summer period more than 16оC significantly reduced this index. The established mathematical dependences enabled to estimate the projected winter wheat yield by the analysis of the temperature regime over the years. The conducted research and established features make it possible to calculate the projected winter wheat yields by the temperature regime of the period from the end of February till the beginning of April. The study of the interrelation between the crop productivity and the combined action of temperature and water regime is supposed to be the next stage of the research.

Formation of Sesame Productivity under the Influence of Agricultural Techniques under Dry Steps of Ukraine

The article is devoted to the study of bioecological features of Ipomoea nil in the conditions of the Tashkent Botanical Garden. Seeds were sown 8 - 10 cm deep in the first decade of April. Seed germination averaged 85% - 90%. The beginning of vegetation and leaf regrowth in Tashkent is observed in the second decade of April. The flowering phase was observed in the first decade of August and fruiting was noted in the first decade of September. Biometric indicators of the plant during the generative phase were revealed as follows: plant height 2.95 ± 0.22 m, generative shoot length 2.62 ± 0.24 m, number of leaves 46.5 ± 3.59 pcs., leaf length 10.11 ± 0.49 cm, root length 19.85 ± 0.88 cm, number of flowers 42.8 ± 2.37 pcs., flower diameter 4.82 ± 0.28 cm. Potential seed productivity (PSP) of the plant was noted 13.5 ± 0.5 pcs., real seed productivity (RSP) was 10.8 ± 0.44 pcs. And in turn, the seed productivity coefficient (SPC) amounted to 80.0% ± 1.31%. The primary results prove, according to the success of Ipomoea nil introduction, the noted indicators in Tashkent conditions.

One of the forgotten crops is turnip, which originates from Western Asia. It belongs to the oldest vegetable plants and has been cultivated by man for over 4 thousand years. Successful cultivation of turnip is possible if the elements of cultivation technology are observed. Therefore, the purpose of the research was to establish the optimal sowing dates of turnip seeds and their impact on plant productivity and quality indicators of the root crop in open ground conditions. The research was conducted in 2023–2024 in the conditions of Western Polissya of Ukraine. Turnip seeds were sown in the 2nd and 3rd decades of April, and the 1st, 2nd and 3rd decades of May. The varieties Zolota Kulya, Purpurlepop, Purpurova and Geisha were used in the experiment. The control was the variant in which the seeds of the Zolota Kulya variety were sown in the 2nd decade of April using a wide-row method with a row spacing of 45 cm. The experiment determined the duration of interphase periods of growth and development of turnip varieties, the mass of leaves and turnip roots, the total yield of root crops and their quality depending on the time of sowing seeds. The study was carried out in three replicates using the randomized block method. As a result of growing turnips, it was found that at early sowing dates (the second and third decades of April), the germination period is shorter, and at sowing seeds at later dates, the germination period is extended and ranges from 8 to 9 days. When sowing turnip seeds in the third decade of April, there is a more active growth of root crops; when sowing in the first and second decades of May, active plant growth and root crop development are observed; when sowing seeds in the third decade of May, better development of the leaf surface is established. The largest mass of root crops is characterized by the turnip variety Purpulepop (388.3 g) when sowing seeds in the second decade of April. The optimal seed sowing date, which contributes to obtaining a higher yield of turnips, is the second and third decades of April, where the value can vary from 23.8 t/ha to 24.9 t/ha of root crops. When sowing seeds in the first and third decades of May, the yield of turnip roots decreases. The highest yield of root crops is characterized by the turnip variety Purpulepop 24.9 t/ha and 24.6 t/ha, which exceeds the yield of the Zolota Kulya variety by 1.5 and 1.2 t/ha, respectively. The highest dry matter content is possible when sowing seeds in the first decade of May for all turnip varieties - (18.89 − 19.51 %), with the varieties Purpurova (19.51 %) and Geisha (18.89 %) standing out; the highest sugar content (10.66 and 11.34%) or an increase of 2.88 % and 2.2 % is possible for early sowing dates (second and third decades of April) for the Purpurova variety; an increase in protein content by 12% is possible for the Zolota Kulya variety when sowing seeds in the third decade of April, and an approximate value is characterized by the Purpulepop varieties (6.63%) when sowing seeds in the second decade of May and the Purpurova variety - 6.61% (third decade of April); vitamin C in root crops can increase by 7-10% for the Purpulepop and Purpurova varieties, the seeds of which should be sown in the second-third decade of April and the first decade of May.