Due to source‐sink relations, a redistribution of plastic compounds occurs between plant organs during their ontogeny. The inflorescence (ear, panicle) is a main sink in annual grasses during their reproductive period. Although source‐sink relations are genetically determined, such factors as weather conditions, mineral nutrition, and biologically active compounds (BAC) could affect them. In this work, we studied the effects of BAC of a new generation on the processes of plastic compound assimilation, accumulation, and redistribution between vegetative and reproductive plant organs. We compared winter wheat cultivars differing in their morphological and physiological traits: moderately high (100‐110 cm) and semi-dwarf (85‐95 cm) ones. Plant treatment was performed at VI‐VII stages of organogenesis. The interspecies hybrid triticale was also used for a comparative analysis of source‐sink relations. Plants were treated with stimulators of humine nature and lignin derivatives enriched in micronutrients. Due to their specific structure and physical and chemical properties, this group of natural high-molecular-weight substances is characterized by a high physiological activity; they stimulate photosynthesis and carbohydrate metabolism. Photosynthesis is known as a basis for plant productivity; however, the process of reutilization of vegetative organ plastic compounds plays similarly an important role [1]. BAC tested favored a greater assimilate deposition in the leaves, stems, and ear structural elements due to increased duration of photosynthesis during reproductive period. Thus, the highest content of dry matter in the leaves was observed by the VIII stage of organogenesis. In triticale, it comprised 24‐28%, in wheat ‐ 23‐25%. At this stage, the proportion of leaves in total biomass was on the average of 20% in triticale and 25% in wheat, the proportion of stems was 65% in triticale and 55% in wheat, and the proportion of ears was 15 and 20%, respectively. By the XII stage of organogenesis, the ratio between organs was changed. In triticale, the ear comprised 43%, stem 52%, and leaves only 5% of total biomass. Thus, in triticale, stems comprised a large portion of the biomass. The analysis of reutilization process showed that 53% of nitrogen and 24% of phosphorus came to the grains from stems. In wheat, the ratio between organ biomass by the XII stage of organogenesis was as follows: in moderately high wheat, ears comprised 51%, stems 41%, and leaves 9% of biomass; in short-stem wheat, the corresponding values were 58, 36, and 6%. Stems provided ears with 35‐42% of secondary nitrogen and about 23% of phosphorus. Thus, the vegetative organs represent a reserve of unused plastic compounds. Therefore,