Formation of the leaf surface area of winter rapeseed depending on the technological methods of cultivation

Purpose. To study the regularities of the formation of dry biomass of winter rapeseed plants depending on the sowing method, seeding rates, level of mineral nutrition and genotypic characteristics of the crop. Methods. Field (phenological observations, determination of leaf surface area in dynamics, accounting of dry biomass at key stages of vegetation), laboratory (determination of the mass of dry matter of one plant, analysis of morphometric parameters of leaves), mathematical and statistical ones. Results. It was established that formation of dry biomass is significantly influenced by the sowing method, the level of resource provision (agrophone) and sowing density. The usual row method at all sowing rates and agrophones provided higher indicators of dry mass accumulation, which is associated with better use of the feeding area and reduced competition between plants. The highest biomass values were recorded in the phase of early ripening at a sowing rate of 0.8 million/ha, fertilizer application and the use of a growth regulator. Comparison of both genotypes showed the advantage of the hybrid in terms of growth intensity and stability of indicators within the variable agrobackgrounds. The positive effect of mineral nutrition was observed in all phases of development, the largest increases were in the phases of budding and full flowering. With an increase in the seeding rate to 1.0 million/ha, a decrease in individual plant mass was noted, which indicates an increase in intraspecific competition. Conclusions. Effective biomass formation is achieved by combining the seeding rate (0.6-0.8 million/ha), the usual row method and full mineral nutrition with a growth regulator. The results have practical significance for improving winter rapeseed growing technologies: optimizing seeding density, nutrition system and genotype selection.