Relevance. Abiotic stress, as heat, significantly affect plant and floral organs growth and development, fruit set, productivity, the quality, and survival of crops. Heat injury occurs when plants are exposed to these temperatures for a long period of time. Depending on the intensity and duration of exposure to the high temperatures, photosynthesis, respiration, membrane integrity, water relations and the hormone balance of the plants may affected.Material and methods. In this study used the commercial pepper cultivar “NW Bigarim” (HT37) released in South Korea and accessions “Kobra” (HT1) and “Samchukjaere” (HT7) selected as heat tolerant and susceptible, respectively. Total chlorophyll index and photosynthetic activities measured using a SPAD meter (Konica, Japan) and portable photosynthesis measurement system (LI-6400, LI-COR Bioscience, Lincoln, NE, USA), respectively.Results. To evaluate the positive effects of high temperature regime (40/28°C day/night, 14/10-h light/dark cycle) on the response of photosynthetic parameters in pepper plants with different heat susceptibility, we measured the total chlorophyll content (CHL) and photosynthetic activities such as photosynthesis (Pn), stomatal conductance to H2O (Gs) and transpiration rate (Tr) in a heat-tolerant (HT1) and -susceptible cultivars (HT7) in comparison with released cultivar (HT37) at fruit development stage. Heat-tolerant cultivars showed higher and more stable index of the CHL, Pn, Gs and Tr than those in heat-sensitive cultivars for 14 days of heat treatment (HT) period. However, the initial index of Pn, Gs and Tr showed significant alteration among pepper plants regardless of thermotolerance rate before HT on day 0 and day 7 after recovery at normal treatment condition (NT) except for CHL, meaning that plants response to high temperature regime is different from that in normal condition. These results suggest that constant high rates of Pn, Gs and Tr as well as of CHL in heat stress condition periods confer to avoid from heat injury during reproductive growth stages.

Relevance. The water regime is one of the main processes in the life of the plant, optimizing which can increase the yield of cultivated crops. In protected ground conditions, the plants' water needs are met exclusively by irrigation. Irrigation is the most important means of increasing the yield of greenhouse crops, including tomato. Greenhouse tomatoes are very demanding on soil moisture, as well as on air humidity. To combat overheating of the air and plants, and to increase the relative humidity of the air in greenhouses, plants for evaporative cooling and humidification of plants are successfully used, which are especially effective in drip irrigation. The combination of drip irrigation with evaporative cooling makes it possible to control the water regime of the soil and air habitat of plants.Materials and Methods. The purpose of the research: to identify the most optimal method of water supply for greenhouse tomatoes. The research was conducted in 2018-2019 in the greenhouse complex "Yugagroholding", located in the suburbs of the city of Makhachkala. The object of research was a hybrid of tomato Mei shuai. The experiments included three options: sprinkling, drip irrigation, and drip irrigation with evaporative cooling.Results. The comparative characteristics of irrigation methods by yield are presented, the results of which indicate the advantage of the second and third options over sprinkling: the highest yield was obtained in the third option and amounted to 14.7 kg/m2 . The best methods of water supply that ensure the optimal water regime of greenhouse tomatoes are identified-drip irrigation and drip irrigation in combination with evaporative cooling, the latter is the best in most indicators.

The data on the greenhouse tomato culture productivity in the long turnover (February November) without application of artificial light are presented. The plants were grown using small-volume hydroponic technology on mineral wool in the industrial greenhouse of LLC "Prigorodny" (Syktyvkar, 61° 40′ 35″ N, 50° 48′ 35″ E). Tomato seeds (hybrid Starbuck F1) were sown in early December 2016. The seedlings were illuminated for 19 h daily with the high-pressure sodiumvapor reflector lamps (HPSV-400W / REFLUX) with an installed power of 130 W/m2. In early February 2017 plants at the age of 4245 days were transferred to the greenhouse and grown at density of 2 plants per square meter under natural lighting conditions. The dependence between the light intensity at leaf level and the natural light entering the greenhouse was studied. In spring sunny days, the light intensity at the level of the upper leaves did not exceed the 450500 μmol quanta/m2s, and in cloudy weather was 2-3 times lower. It was found that the saturation of leaf CO2-uptake by light took place at intensity of 800-1000 μmol quanta/m2s. The leaves formed under light deficiency had lowered photosynthetic activity (near 3 μmol СО2/m2s). The maximal productivity of tomato culture was observed during maximum light levels and sunny period (June-July). The average value of tomato productivity was about 34 kg/m2. The data show the possibility of producing commercial tomato yield in the first light zone without artificial lighting, which significantly reduces production costs.

The field experiment has revealed that application of green manure and mulching of seedlings by organic matters and zeolite-containing clay increases the amount of nitrogen, phosphorus, and improves agro-physical parameters of soil. As consequence the yield of red beet has increased up to 14-34%, the root weight has increased up to 11-16 g, and the standard output has increased up to 3-7%. The improvement of biochemical and phytosanitary quality of roots was revealed.

The study of net productivity of photosynthesis of tomato in continuous culture has been conducted during 2010-2013. The influence of two-year interruption by crop rotation link and different systems of fertilization on the growth of vegetative mass (g/m2 per day) was determined.

The advantages of pre-sowing seed soaking in phytoregulator solutions such as Hitofos, Phytohit, Cytohit and some foliar feeding were shown at the time of carrot plants grew. As it was revealed previously at Breeding Production Stations, Urus-Martanovskiy region, the «Gribovchanin» carrot cultivar had a yield characteristics and quality of root that became much higher after seed and plant treatment by physiologically active substances.

The data of yield and tuber quality of earlyripening potato varieties obtained during tuber-formation in the forest-steppe zone of Tyumen region are presented. It was found that cv. Vesna, cv. Severniy, and cv. Red Scarlet are differed in their pattern of tuber formation in different time of growing. The cultivars Alena, Severniy, and Karatop are characterized by high starch accumulation and good taste qualities.

In field experiments, the optimal pre-irrigation moisture levels of the soil, plant density and fertilizer regulations to ensure maximizing the table beet crops with good qualities of roots under foothill zone of the Chechen Republic have been found.

The leaf-area duration and photosynthetic yield in early-maturing tomato varieties were studied in terms of planting system and degree of density of plants.

Relevance. In modern climatic conditions, the suppression of production process occurs against the background of short-term or long-term exposure to unfavorable environmental factors on agricultural plants, and, therefore, yield decreases. In this regard, there is a need for the use of growth regulators with protective and stimulating effects on many physiological processes.The aim of the work was to study the influence of the element selenium and 6-benzylaminopurine on the production process of red currant.Methods. Foliar treatments with solutions of sodium selenite and 6-benzylaminopurine (6-BAP) were made after flowering plants of the Dana and Asya varieties of the VNIISPK. The currant leaves were taken from annual shoots for determine the content of abscisic acid (ABA), the amount of pigments, and the rate of light reactions of photosynthesis. The parameters of the fruit brush of plants were recorded.Results. It was shown that treatments with sodium selenite and 6-benzylaminopurine contribute to a decrease of 2.1-3.5 times in the leave tissues of the endogenous ABA level, increase the chlorophyll biosynthesis by 27.5-48.0% and accelerate by 19.3-45.8% electron transfer rate on the level of light photosynthesis reactions. Treatment with selenium and 6-BAP of Dana plants increased the average mass of the fruit brush by 19.30% and 24.5%, respectively, Asya varieties by 20.7 and 35.8%. The increase in the average mass of the fruit brush occurred due to the enlargement of the average mass of one berry in it. It was shown that selenium and 6-BAP in the Dana variety increased the weight of the berry by 27.3% and 47.3%, in Asya by 33.3% and 45.8%. The treatment did not have a significant effect on the amount of sugars. Thus, for increase the production process, it is advisable to make foliar treatments with sodium selenite and 6-BAP during the growing season on red currant plants.