The article presents a study of changes in the functioning of the source-sink system in the heterotrophic phase of development of horse beans (Vicia faba L.) under the conditions of the artificial combination of external (darkness) factor and internal factor (antigiberelline retardant) during germination. It was found that the action of the drug significantly reduced the length of the epicotyl, root and total seedling. Similarly, the dry matter mass of the seedling organs decreased. The level of using seed spare substances under the influence of retardant decreased, as evidenced by the maximum dry matter of cotyledons in plants of this variant and a decrease in the utilization of reserve substances for root and epicotyl formation during germination. Tebuconazole inhibited the breakdown of starch in the dark. The higher content of sugars in the seeds of scotomorphic plants in comparison with the control is associated with a less intensive outflow for the needs of organogenesis – the formation of root and epicotyl structures. Quantitative changes in nitrogen content in scotomorphic seeds were much smaller than changes in starch content. This indicates that the retardant in the dark inhibits the hydrolysis of the reserve protein of the seed, but the process is started after the hydrolysis of starch. The purpose of the study was to establish the effect of tebuconazole on the processes of germination and redistribution of carbohydrates in seedlings of Vicia faba L. Material and methods. The work was carried out on seedlings of horse beans (Vicia faba L.) of Vivat variety, which is a medium-ripe high-yielding variety with a vegetation period of 100-105 days. The variety is technological, resistant to major diseases, has high resistance to lodging, shedding of beans and their cracking. Results and discussion. The combined effect of darkness and the drug of anti-gibberellin action of tebuconazole were used to regulate the intensity of source-sink relations during the germination of horse bean seeds. The seeds of the experimental variant were soaked for a day in 0.5% solution of the triazole-derived drug tebuconazole. Tebuconazole is a transparent crystalline substance of hazard class 3. The seeds of the control variant were soaked for 24 hours in distilled water and sown in cuvettes with wet sand. The biological replication of the experiments is fivefold. The experiment was performed under the action of light and in dark in order to study the implementation of programs of skoto-and photomorphogenesis. Morpho-biometric parameters (root length, seedling length, dry matter weight of individual organs and the whole plant) were determined on the day of 18 of germination. Determination of nitrogen content was carried out according to Keldal method, starch in the organs of seedlings was performed by iodometric method, to determine the content of total sugar and reducing sugar we used Bertrand method in modification by V. Kosolapov. Conclusion. The combination of exogenous and endogenous factors during seed germination significantly changed the intensity of donor-acceptor relations in horse bean seedlings. Under the action of the drug significantly slowed the growth of seedlings in the dark. There was the decrease in the dry matter of the organs of the seedling in dark and noted lower rates of use of reserve substances for organogenesis during germination
Keywords: retardant, scotomorphogenesis, Vicia faba L., germination
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