Changes in the Phytochemical Composition of Humulus lupulus L. under the Influence of Bioregulators

Plants have high physiological adaptability to changing environmental conditions, one of the mechanisms of which is the synthesis of secondary metabolites that perform functions of protection against oxidative stress. An important area of modern plant physiology is the targeted study of the effect of growth regulators (GR) on the biosynthesis of valuable secondary metabolites and increasing plant resistance to stress factors. The aim of this work was to evaluate the effect of treatment with plant growth regulators and biofertilizer on the content of xanthohumol, α- and β-acids, water-soluble phenolic compounds, flavonoids, tannins and essential oils in Humulus lupulus L. cones. It was found that the most pronounced stimulating effect on the biosynthesis of secondary metabolites was provided by treatment of plants with the bioreglator “Epin-Extra”, leading to an increase in the content of xanthohumol (XN) by 2 times, α- and β-acids, as well as the yield of essential oil by 3 times and the content of tannins by 57.84%. The use of the bioregulator “Gibbersib” stimulated the accumulation of flavonoids by 64.48% and increased the yield of essential oil by 70%, while the biofertilizer “Pudret” increased the content of water-soluble phenolic compounds by 69.88%. The obtained data confirm that exogenous application of GR and biofertilizers is an effective tool for targeted modification of the phytochemical profile in hop cones. This approach opens up prospects for optimizing the quality characteristics of hop raw materials in accordance with the requirements of various industries—from food and pharmaceutical to cosmetics—and contributes to increasing its commercial value. In addition, the results of the study demonstrate the potential of using growth regulators and biofertilizers in the development of innovative strategies for increasing hop resistance to abiotic stressors, which is a key factor in ensuring production stability in the context of climate change.