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, photo- and skotomorphogenesis processes.

Functional changes in the source-sink system of maize sprouts under combination of external (light/dark) and hormonal (gibberellic acid/retardant) factors during germination were studied. It was found that the phytohormone action significantly increased the coleoptile, root and seedling length, dry matter mass of organs, both in light and in dark. Tebuconazole caused the opposite effect due to its retardant action. The inactivation of endogenous phytohormone was confirmed by less intensive use of seed substances, the minimum dry matter of root and coleoptile and lower reserve utilization rates under tebuconazole influence, in particular under photomorphogenesis condition. The non-maximum mass of cotyledons may indicate a kind of optimization of use of reserves under tebuconazole treatment. Gibberellin stimulated starch breakdown in both light and dark, but starch usage was higher in dark. The lower content of sugar in the seeds of skotomorphic plants in control and under gibberellin action was explained by intense outflow for the organogenesis needs. Gibberellin stimulated the hydrolysis of reserve protein after intensive starch hydrolysis in dark. Specific gibberellin regulation of phosphorus outflow for the organogenesis processes under the photo- and skotomorphogenesis conditions and no regulation for potassium under photomorphogenesis conditions were found.