Thermal balance of greenhouse complexes of the V generation in the summer period

When growing various crops in greenhouses an important condition for obtaining high yields is compliance with the required parameters of the temperature regime of the air environment. The air conditioning systems currently used in greenhouses of the V generation “Ultra Clima” are equipped with adiabatic panels that cool the air entering the room by evaporation of moisture from their surface. However, in some cases, such systems are not able to support the required values. This is due to the large heat flows entering the greenhouse in the summer. The paper analyzes the temperature balance of the air environment of greenhouses of the V generation, evaluates the main heat flows, determines the operating modes of cooling systems that guarantee sufficient cooling capacity to achieve the required temperatures in the room.

Phytoplankton Communities and Cyanotoxin Production in Some Bulgarian Lowland Lakes and Reservoirs

One of the most evident consequences of eutrophication of waters is the progressive spreading of persistent cyanobacterial blooms. They are often accompanied by the production of cyanotoxins in concentrations, which are hazardous for human health. In this research, we analysed phytoplankton communities in four lowland water bodies, for the presence of cyanobacterial blooms and toxin production. The cyanobacterial biovolumes we found, determine three of the lowland water bodies: Onogur Reservoir (OR), Asparuhov Val Reservoir (AVR), and Srebarna Lake (SL) as “Alert Level 1” of potentially hazardous levels of cyanotoxins. Cyanobacterial biovolume exceeds the threshold value of 8 mm3 L-1 (recreational waters) in AVR and SL at the end of the summer period. In OR, we registered sustainable bloom of Microcystis spp. during the whole summer season, and extremely high average seasonal value of the total biovolume (146.5 mm3 L-1). Micro-cystins were reported in all four analysed water bodies, with the highest concentration in OR (6 µg L-1). Cylindrospermopsin was detected in AVR and OR, while saxitoxins were in AVR and SL. The concentrations of cyanotoxins do not exceed the guideline values in recreational waters. However, the increased biovolumes of cyanobacteria are a signal that in three of the analysed water bodies, monitoring is recommended at the levels of cyanotoxins during the summer period.

Influence of seasons on heart rate variability during cognitive activity in students with different types of daily activity

It is shown that changes of heart rate variability (HRV) in students with morning, afternoon and evening chronotypes under cognitive load are characterized by seasonal dependence. A more pronounced seasonal modulation of HRV is characteristic of "pigeons", whose background values of HRV parameters and responses to load during the school day are greater in the autumn-winter period than in the spring-summer period. In" larks", HRV changes in the conditions of cognitive activity dominate in the spring-summer season, and in "owls" – in the autumn-winter season, but the observed reactions are weaker than in "pigeons". The observed differences in HRV may be caused by seasonal features of mechanisms of the heart adaptation in different chronotypes. Keywords: heart rate variability, seasons of the year, chronotypes, cognitive load.

Influence of conditions of keeping bee families in wintering on their productivity

Creating favorable conditions for the development of bee colonies, adherence to technological techniques and processes are of great importance in increasing productivity. The article highlights the results of research on the impact of increased subframe space during the wintering of bee colonies on their further development and productivity. In the course of the research, bee colonies were evaluated on the basis of a set of economically useful traits. For research, 2 groups of bee colonies were identified, 10 in each, equivalent in strength and food security, with young fertile queens bred in the same year. The formation of experimental groups took into account the strength of bee colonies, the number of closed brood, the age of the queens, the availability of feed (honey and perga), and the quality of nest cells. These indicators in the experimental groups were almost the same. When preparing bee colonies for winter, the frames in the families of the control group were in the center of the hive, removed the top insulation and unscrewed the sheets by 5–7 sm in the experimental group performed the same actions as in the control winters substituted empty store extensions, thus increasing the subframe space. During the research, honey and wax productivity, strength of families in different periods of the active season and winter hardiness were determined. It was found that bees kept in the hives with increased subframe space, in which 76.1 % less plague was detected, compared with the control group, tolerate wintering well. These families are developing more intensively in the spring and summer period – the advantage in strength was 25.8 % in April, 31.4 % in May, and 31.6 % in June. And further they show higher honey and wax productivity by 24.9 and 32.1 %, respectively.

Application of the time transgrassive aerospace information for assessment of avalanche activity and hazard (Central Caucasus)

На основе дешифрирования разновременных аэрофотоснимков с 1957 г. по 1988 г. и космических снимков с 2005 г. по 2020 г. приведены данные о лавинопроявлениях в районах Центрального Кавказа (бассейны рек Баксан, Черек и Мамихдон). Факты схода лавин устанавливались в результате сравнения разновременных аэрокосмоснимков и их GIF-анимаций по особенностям теней заснеженных поверхностей от неровностей отложений лавин, наличию лавинных снежников в весенне-летний период, по характеру и ареалам растительности, а так же по уникальному космоснимку в момент схода ла- вины. Based on aerial photographs interpretation from 1957 to 1988 and satellite images interpretation from 2005 to 2020, data on avalanche phenomena in the regions of the Central Caucasus (basins of the Baksan, Cherek and Mamikhdon rivers) are presented. Avalanche facts were established as a result of comparing different-time aerospace images and their GIF animations on the features of shadows of the snowy areas from the irregularities of avalanche deposits, the presence of avalanche snow-patch in the spring-summer period, in nature and vegetation ranges, as well as on a unique space image at the time of avalanche.

Trophic migrations of the brown bear in the forest landscapes of the Vostochny Nature Reserve on Sakhalin Island

The article deals with trophic migrations of the brown bear in the characteristic forest landscapes of the Vostochny Nature Reserve. Active life of a bear in the reserve begins after hibernation and is directly related to foraging in different seasons of the year. In the spring-early summer period, bears concentrate in valley forest complexes and coastal-marine landscapes, where, along with plant food, they obtain various products of animal origin thrown out of the sea. During the summer period, from the beginning of the course of salmon and until the end of their spawning, the animals mainly live in the mouths of rivers, and as the fish move, they go upstream and are distributed among their numerous tributaries. During the autumn period, bears concentrate mainly in mountainous forest landscapes and high-altitude natural complexes of the reserve, where they eat ripe berries and pine nuts, their trophic migrations are significantly reduced.

The results of the use of imported from the USA semen of breeding bulls in the Nizhny Novgorod region

Purpose: Study of the results of the use of bull-producers imported from the United States in the conditions of the Nizhny Novgorod region.Materials and methods. The work was performed in 2018-2019 in the farms of the Nizhny Novgorod region. The object of study - the heifers of the Holstein breed, which reached 360-380 kg of a living mass aged 13 months and above. Total experience used 495 heifers. Feeding chubs was carried out in accordance with feeding norms, taking into account the physiological state of animals. The insemination of the heifers was carried out by the rectocervical way after synchronization of hunting. We studied the number of seeds, the pregnancy from one insemination, the number of abortions and the number of repeated pubs within a month after the hotel. Statistical analysis of the data obtained was carried out in the SPSSV.15.0 program.Results. It has been established that more than 70% of the heifers were invented at the age of 13-15 months. The pregnancy from one insemination was 58%. The best result (72.2%) was obtained in the group of heifers aged 19 months and above. The results of the study show that the seed season plays an essential role in seeding. The best indicators were obtained in the summer period - 60%, in autumn - 54% and in winter - 56%.Conclusion. The data obtained give reason to believe that the optimal age of the insemination of the heifer is 13-15 months. The result of artificial insemination of the heifer has an influence of the season of the year in the insemination and season of birth of heifers, while the birth season as a factor has a higher value.

Effect of temperature and relative humidity on the milk production of dairy cows

The aim of this study was to evaluate the influence of environmental housing conditions on the milk yield of dairy cows. Measurements were taken in the summer period from June to September 2020 and in the winter period during January 2021 on a large-capacity farm of Holstein Friesian cattle. Cows were housed in free stall barn with the lying boxes and selected during the second or third lactations, in the summer period from the 51st day to the 135th day and in the winter period from the 64th day to the 120th day of lactation. The average temperature in the housing was 23 °C in summer, and 7.05 °C in winter. The average THI (thermal humidity index) value in summer was 70.43, but during the day the THI values sometimes reached 75. The dairy cows were therefore exposed to heat stress during summer. Increasing THI and temperature values negatively affected the milk yield, as there was a negative correlation between both THI and milk yield (r = -0.641; p <0.01) and temperature and milk yield (r = -0.637; p <0.01). Milk production in winter was at 58.77 kg per day and in summer at 49.55 kg per day. In the summer, the milk had a significantly lower content of fat (p <0.05), proteins (p <0.001), lactose (p <0.001), minerals (p <0.001) and conversely, a higher number of somatic cells (p <0.01). These results show that worse environmental conditions during the summer negatively affected the level of milk yield and the composition of the cows’ milk.