Regulation of growth and development of cultivated plants in order to optimize the production process is one of the main objectives of modern plant physiology. Both activators and growth inhibitors are used for this purpose. The effect of foliar treatment with 0.005% solution of gibberellic acid and 0.025% solution of antigibberellic preparation of tebuconazole on the morphogenesis, leaf structure, photosynthetic pigment content, balance of phytohormones and eggplant productivity cv. Diamond variety was investigated. The treatment with the preparations was carried out in the budding phase. The vegetation experiment was laid under soil and sand culture in vessels of a ten-liter capacity. The morphometric parameters were determined every 10 days, the mesostructure was studied in the leaves of the middle tier in the phase of fruit formation, chlorophyll content was measured in the raw material by spect­rophotometric method. Analytical determination of phytohormones (indole-3-acetic acid, gibberellic, abscisic acids and cytokinins – zeatin, zeatin-O-glucoside, zeatinriboside, isopentenyladenine and isopentenyladenosine) was performed by high performance liquid chromatography. Under the action of gibberellic acid, plant height increased significantly, and it decreased after its treatment with tebuconazole. The stimulator and inhibitor increased the number of leaves per plant, the weight of the leaf dry matter, the area of the individual leaf blade and the area of leaves per plant. Both preparations increased the weight of the raw material of the stems and roots, as well as the mass of dry matter of the whole plant. Under the action of tebuconazole, the content of chlorophylls in the leaves increased, while under the action of gibberellic acid it decreased. After treatment with gibberellic acid and tebuconazole, the thickness of the leaf blade increased due to chlorenchyma thickening. In the variant with gibberellic acid, the thickness of upper and lower epidermis increased, and in the variant with tebuconazole, these parameters decreased. Both growth regulators increased the volume of cells of the columnar parenchyma. The contet of endogenous gibberellic, indole-3-acetic and abscisic acids of the stems and especially in the leaves increased with the treatment of exogenous gibberellic acid, whereas after the application of tebuconazole the gibberellic and indole-3-acetic acid content of the stems decreased significantly and practically decreased to traces. Instead, the amount of abscisic acid increased. After treatment with exogenous gibberellic acid, the pool of cytokinins in the leaves significantly decreased. The inactive isoforms of the hormone zeatin-O-glucoside and isopentenyladenosine dominated in the stems. The effect of tebuconazole decreased the pool of cytokinins in the stems and increased in the leaves. In general, due to the multidirectional action, growth regulators positively influenced the elements of eggplant productivity. More effective was the retardant – tebuconazole. Therefore, the anatomic-morphological and structural-functional rearrangements in eggplants under the effects of exogenous gibberellic acid and tebuconazole are due to changes in the balance and distribution of endogenous hormones. Increased photosynthetic activity, stimulation of growth processes of some organs of the plant and inhibition of others enlarged the biological productivity of the culture.

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.

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.

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.