Effect of gibberellin on the use of reserve substances deposited in Vicia faba L. seeds at the phase of heterotrophic development under the conditions of photo- and skotomorphogenesis

2 Vasyl Stus Donetsk National University, 600-richya St., 21, Vinnytsia 21021, Ukraine Under conditions of a combination of an external (light/dark) factor and a hormonal factor (gibberellic acid) during germination, changes in the functioning of the source-sink system in heterotrophic phase of horse beans development were studied. The increase in the epicotyl, root and seedling length, both in light and dark, as well as in the dry matter of the mass of the seedling organs, was found under drug action. Reserve substances were used more intensively under gibberellin and skotomorphogenesis influence. It is evidenced by the minimum dry matter of cotyledons and higher reserve utilization rates for root and epicotyl formation. Gibberellin stimulated starch breakdown in both, but during germination in dark, the rate of starch use was higher. Other content of sugars in skotomorphic seeds was associated with more intensive outflow for organogenesis needs: formation of root and epicotyl structures. The changes in the content of starch were higher than the changes in nitrogen content in skotomorphic and photomorphic seedlings. This indicates that gibberellin stimulates hydrolysis of reserve protein only after starch hydrolysis in dark. No specific gibberellin regulation of phosphorus and potassium outflow from seeds for organogenesis needs was found, suggesting sufficient mineral nutrients supply to ensure their re-utilization during germination, photoand skotomorphogenesis processes.