Kravets O. Physiological bases of growth regulation and morphogenesis of tomatoes under gibberellin and retardants treatment

In the thesis it was studied the features of growth processes, morphogenesis and functioning of donor-acceptor system of tomatoes (Solanum lycopersicum L.) under the influence of gibberellin (gibberellic acid, GA3) and its antagonists – triazole derivative tebuconazole and ethylene releasing compound esphon in the formation of crop productivity. Gibberellic acid (GA3) and retardants caused a clear growth regulating effect on the intensity of plant growth, accompanied by changes in relative proportion of vegetative organs weight. Application of tebuconazole resulted on the formation of a more powerful donor sphere, where relative proportion of leaf weight in the total vegetative weight of plant was higher during whole vegetation stage. The mesostructure measurement of leaves was optimized under gibberellin and tebuconazole treatment: thickness of leave increased by enhancement of linear dimention of spongy parenchyma cells and volume of palisade parenchyma cells. It was found that leaves of tebuconazole and gibberellin treated tomatoes were characterized by the highest measurements of leaf area density value, chlorophyll content and net photosynthetic productivity which created the prerequisites to enhance gross photosynthetic crop production. It was established that stems and roots are characterized by intensive depositing possibilities of nonstructural carbohydrates that remobilized to carpogenesis needs (fruit formation and growth). Reducing of sucrose content in leaves of treated plants with a simultaneous increase of reducing sugars content at the fruitification stage (brown ripeness) indicated that transport of sugar from leaves to fruits ceased earlier than from root and stem. Preparations treatment significantly influenced on the reutilization of nitrogen, phosphorus and potassium from stem and leaves. This process was more intensive under gibberellin and triazole derivative tebuconazole. We concluded that a significant increase the yield of tomato crop in the conditions of field experiment was caused by triazole derivative tebuconazole. In the conditions of vegetative experiment with stable water supply, the maximum value of this indicator was under gibberellin. Application of ethylene releasing compound esphon at the stage of 25 % fruit ripeness significantly accelerated the rate of their ripening, which led to a reduction in the number of harvests and an increase in the share of early crop production. The maturation of tomato fruit was largely determined by the intensity of maceration of fruit tissues, which is based on the processes of hydrolysis of cell wall polysaccharide components – hemicelluloses and pectins.