The influence of preparations of phytohormone gibberellin and antigibberellin–retardants tebuconazole and chlormequat chloride – on the germination of plant seeds with different types of reserve compounds in the light (photomorphogenesis) and in the dark (skotomorphogenesis) was studied. It was established that under the action of gibberellin, stimulation of the aboveground part and root system growth of maize, beans and pumpkin seedlings was more intensive in comparison with the control. This process was faster in the dark. The use of tebuconazole and chlormequat chloride significantly inhibited the process of germination both in the light and in the dark. At the same time, the coefficient of the use of reserve substances was maximal under the action of gibberellin, and minimum under the action of retardants, both under the conditions of skoto- and photomorphogenesis. The change in the growth characteristics and the coefficient of the use of reserve substances of bean seeds was accompanied by a decrease in the content of total nitrogen, indicating the use of reserve nitrogen-containing compounds in the processes of morphogenesis. The content of protein nitrogen in the control was lower under the conditions of skotomorphogenesis than in the photomorphic seedlings, and the opposite effect was noted for the actions of gibberellin and the retardant. In the later stages of germination, the largest reserve oil of pumpkin seed remained in cotyledonary leaves of photomorphic plants under the effects of chlormequat chloride, which clearly correlated with the least intense growth rates of seedlings in this variant, both in the light and darkness. Under conditions of skotomorphogenesis the growth stimulating effect of gibberellin significantly increased, and the light blocked the action of this phytohormone.

We investigated the effect of gibberellin and the antigibberellic agent chlormequat-chloride on gas exchange and use of reserve substances in pumpkin seedlings during germination in the light and in the dark. We established that an artificial strengthening or growth inhibition of pumpkin seedlings in conditions of skotomorphogenesis caused an increase in of respiration intensity. Gibberellin treatment increased the proportion of assimilation processes in carbon dioxide gas exchange of seedlings, and growth inhibition by retardant caused an increase in respiratory costs when the nutrition type switches in the light from heterotrophic to autotrophic. The formation by seedlings of the demand for reserve assimilates from cotyledons was largely determined by change of activity of subapical meristems, which is manifested in the acceleration of seed germination, enhancing of histogenesis for the actions of gibberellin and in the weakening of these processes under the influence of retardants. Reserve substances used both oil and nitrogen-containing compounds. The content of protein nitrogen in pumpkin cotyledons decreased more in the light than in the dark, moreover growth inhibition by the retardant slowed down and growth increase by gibberellin accelerated this process both in conditions of photomorphogenesis and skotomorphogenesis.

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We investigated the influence of gibberellin and antigibberellin agents (tebuсonazolе and chlormequat-сhloride) on the growth, development, leaf apparatus, formation of the mesostructure, net photosynthetic productivity, contents of different forms of carbohydrates and nitrogen compounds in the vegetative organs of potatoes of the Sante sort and their productivity. We established that the use of tebuconazole and chlormequat-сhloride reduced the linear dimensions of plants and increased the number of leaves on them, the mass of damp matter of leaves and their area. Gibberellic acid increased plant height and leaf area significantly. Gibberellic acid and tebuconazole thickened the laminae by cell proliferation of the main photosynthetic tissue – chlorenchyma. The volume of the cells of palisade parenchyma increased under the influence of these agents. The size of the spongy parenchyma cells increased due to the action of the growth stimulator. The content of chlorophyll in potato leaves was reduced significantly after processing by gibberellic acid and it grew after application of tebuconazole. Content of photosynthetic pigments tended to increase due to action of chlormequat-сhloride. It was found that retardants increased starch content and protein nitrogen in the roots, stems and tubers with a simultaneous decrease in the sugar content of the vegetative organs. Gibberellic acid reduced the content of sugar and starch in the roots, stems and leaves and increased their content in the tubers. The hormone reduced content of protein nitrogen in leaves. Gibberellin and antigibberellin agents increased the weight of dry matter in the plants, raised net photosynthetic productivity and optimized productivity of the culture. Treatment of potato tubers with the retardants during the dormant period led to slower germination, which contributed to preservation of production.

Using growth stimulators and anti-gibberillin preparations of different chemical compounds, we created different pressures in the coordinate covalent bond systems during germination of sunflower seeds. Using gibberellin and treptolem growth stimulators and Paclobutrazol and Chlormequat-Chlorid anti-gibberillin preparations is an efficient method of reconstructing coordinate covalent bond during the germination of seeds of oil-bearing crops. It allows determination of the role of the hormone factor in the utilization of reserve lipids over the heterotrophic phase of plant development. Blocking the synthesis of gibberellins by retardants caused decrease in activity of lipase, hydrolysis of reserve lipids and the meristem, which resulted in decrease in the energy of germination. Compared to the control, the impact of gibberellin increased the content of butyric acid, and the impact of Paclobutrazol reduced the content of butyric acid. Linoleic acid showed exactly the opposite changes. In relation to the control, a significant increase in the content of non-saturated linoleic acid was observed in both variants of the experiment. Gibberellic acid stimulated and Paclobutrazol slowed the usage of free higher fatty acids for the process of morphogenesis.

The regulation of plant growth and development under application of antigibberellin compounds is accompanied by changes in the donor-acceptor system that in turn affects the accumulation and redistribution of carbohydrates and nitrogen-containing compounds. We studied the influence of tebuconazole 0.025% (EW-250) and 0.05% and 0.07% esphon (2-CEPA) on growth processes, leaf apparatus and content of various carbohydrate forms and total nitrogen content in vegetative organs of tomato hybrids Bobkat and Solerosso. A field-based micro-trial setup was established from 2013 to 2017. The plants were treated via foliar spraying with aqueous solution of retardants at the time of initiation of budding. Phytometric measurements were determined every 10 days, the content of various carbohydrate forms and total nitrogen in organs of plants was determined by using biochemical methods in a fixed dry material (the content of sugars and starch – by iodometric method, and the total nitrogen content – by Kjeldahl). It was found that both retardants reduced the linear growth of tomato plants. The results indicate that 2-CEPA treatment significantly decreased the plant height of both hybrids. Application of drugs increased the number of leaves per plant. The leaf dry matter weight increased, the most significant effect was created by EW-250. The leaf area of the retardant-treated tomatoes hybrid Solerosso increased and decreased in the hybrid Bobcat. Application of antigibberellin compounds intensified the outflow of sugars and remobilization of starch in roots and stems of both tomato hybrids. The content of starch, reducing and non-reducing sugars in leaves of hybrid Solerosso was higher after EW-250 treatment. 2-CEPA increased the content of reducing form of sugars, and EW-250 increased non-reducing form in the hybrid Bobkat. EW-250 intensified the accumulation of carbohydrates in fruits due to reducing sugars in both tomato hybrids, whereas 2-CEPA reduced their content compared with control. Growth inhibitors increased the starch content in fruits at the beginning of vegetation and intensified its reutilization at the end. This process was most intensive was in variant of EW-250-treated plants regardless of hybrids. We proved that there was a clear tendency to decrease the ratio of sugar content to starch in almost all organs of both tomato hybrids during the growing season. The most significant was the reduction of this ratio after EW-250 treatment. At the fruitification phase, the proportion of starch in retardant-treated plants increased compared to the control. The increased accumulation of carbohydrates in tomato fruits treated with EW-250 caused an increase in the average weight of the fruit. We have found that the total nitrogen content in vegetative organs decreased in the control and in the experimental variant of both tomato hybrids during vegetation. EW-250 accelerated the outflow of total nitrogen from roots and stems and increased its content in leaves. This drug retarded the accumulation of this element in fruit. Such changes in the dynamics of total nitrogen under the influence of tebuconazole resulted in enhanced formation of fruit on tomato plants. We concluded that the antigibberellin compounds EW-250 and 2-CEPA due the action on growth processes and leaf apparatus of tomato plants, changed the character of donor-acceptor relation through an increase in outflow of plastic substances from vegetative organs to fruits, which optimized the crop production.

One of the main tasks of modern plant physiology is regulation of growth and development of cultivated plants in order to optimize the productive process. The attention of the scientific community is focused on the use of natural activators and growth inhibitors. We investigated the effect of foliar treatment with 0.005% solution of gibberellic acid (GA3) and 0.025% solution of the antigibberellic preparation tebuconazole (EW-250) on morphogenesis, leaf mesostructure, the content of photosynthetic pigments, the balance of endogenous phytohormones and productivity of Capsicum annuum L., Antey variety. The vegetation experiment was carried out in the conditions of soil-sand culture in vessels with a volume of 10 L. Treatment of plants was carried out in the budding phase. Morphometric parameters were determined every 10 days. The mesostructure of the middle tier leaves was studied in the fruit formation phase, and the chlorophyll content was determined in the raw material by spectrophotometric method. Analytical determination of endogenous phytohormones – indolyl-3-acetic (IAA), gibberellic (GA3) and abscisic (ABA) acids and cytokinins – zeatin (Z), zeatin-O-glucoside (ZG), zeatinribozide (ZR), isopentenyladenine (iP) and isopentenyladenosine (iPA) were performed by high performance liquid chromatography – mass spectrometry (HPLC-MS). With GA3 treatment, plant height increased considerably, while with EW-250, it decreased. Both regulators led to an increase in the number of leaves on the plant, the leaf raw biomass, stems and roots and the dry matter of the whole plant, the area of a single leaf blade and the total area of leaves on the plant. Under the action of EW-250, the chlorophyll content in the leaves surged, while under the action of GA3 it tended to decrease or did not change at all. Both regulators thickened the chlorenchyma and boosted the volume of the columnar parenchyma cells. GA3 treatment induced a rise in the thickness of the upper and lower epidermis, and EW-250 led, on the contrary, to a decrease. It is shown that after treatment with exogenous GA3, the content of endogenous IAA and ABA decreased and GA3 in plant stems increased. Instead, EW-250 caused a decrease in the levels of GA3, IAA and ABA in the stems. Exogenous GA3 enhanced the accumulation of endogenous GA3 and IAA and inhibited ABA in the leaves. Under the action of the retardant, the level of ABA in the leaves did not change, while GA3 and IAA decreased. Treatment of plants with the studied growth regulators caused a decrease in the pool of cytokinins (CK) in stems. EW-250 showed a significant rise in the hormone content in the leaves. After spraying with GA3 solution, the level of ZG, Z and ZR grew. Under the action of the retardant, the increase in the CK pool occurred exclusively due to the iP. Growth regulators optimized the productivity of sweet pepper plants: under the action of GA3 there was an increase in the number of fruits per plant, and after the use of EW-250 there was a rise in the average weight of one fruit. The obtained results showed that anatomical-morphological and structural-functional rearrangements of sweet pepper plants under the action of exogenous gibberellic acid and EW-250 took place against the background of changes in the balance and distribution of endogenous hormones. Increased photosynthetic activity, stimulation of growth processes of some plant organs and inhibition of others enlarged biological productivity of the culture.

We studied the comparable effect of gibberelic acid and tebuconazole on morphogenesis, mesostructure formation and redistribution of flows in sweet peppers and tomatoes. It has been found that the use of gibberelic acid and tebuconazole retardant during budding leads to increased plant productivity due to optimization of the structure and operation of the plants’ leaf apparatus. It was established that both gibberelic and antigibberelic tebuconazole drug stimulated the formation and functioning of the photosynthetic apparatus of peppers and tomatoes, but the mechanisms of this regulation were different. Increased photosynthetic activity of plants under the influence of gibberellin was determined primarily by the formation of more leaves and total leaf surface. When using tebuconazole retardant there was a significant restructuring of the organization of leaf mezostructure: the leaves were thickened by chlorenchyma proliferation, there was an increase in the volume of columnar parenchyma cells and linear dimensions of spongy parenchyma leaf cells. The surface density of leaves significantly increased, the chlorophyll content and nitrogen content (especially protein) also increased, compared with control variants and variants using gibberelin. Such a profound restructuring of the photosynthetic apparatus in plants under the actions of tebuconazole led to a significant increase in donor leaves function of peppers and tomatoes, which is an indicator of the growth of net productivity of photosynthesis – the highest among all the variants of the experiment. The results also show that increasing the chlorophyll phytocenotic index was more significant than the increase of leaf index: the tomatoes under the action of tebuconazole had a lower leaf index than in control options, but due to a higher chlorophyll index the crop productivity increased.Since during the fruiting period the costs of assimilates to the growth of vegetative organs are greatly reduced, optimization of photosynthetic apparatus in pepper and tomato plants led to the laying of more fruit per plant and increasing crop yield. The analysis of the mass ratio of the researched vegetative and fruit plants shows that the mass fraction of fruit (an acceptor sphere of plants during fruiting) under the action of both drugs increased. Thus in both variants of the experiment both the mass fraction and donor assimilates of leaves were higher. Apart from the main source of assimilates – the processes of photosynthesis, which intensified due to the formation of a larger area of leaf surface (variant with gibberelin) or optimization of mesostructure (variant with tebuconazole) it is probable that the formation and growth of the embryo occurred in part due to reutilization of carbohydrates from the vegetative plant organs in carpogenesis processes.