PHENOLIC CONTENT AND ANTIOXIDANT CAPACITY OF WILLOW BARK OBTAINED IN AN ANNUAL CUTTING CYCLE*

Willow bark is an interesting source of bioactive substances. However, the extremely wide diversity of willow species and genotypes makes it necessary to search for the most useful ones. Preferably, the bark of the best willow genotypes should come from field plantations, which would guarantee the high quality and stability of this bioresource. Therefore, the aim of this study was to determine the phenolic and flavonoid content, the antioxidant capacity as well as the potential yield of bioactive substances from bark of ten willow genotypes harvested in two annual cutting cycles. The research material consisted of the bark of four genotypes of Salix purpurea, two genotypes of S. americana, two genotypes of S. triandra and two genotypes of interspecies hybrids of S. purpurea x S. daphnoides. One-year-old willow shoots where harvested in March 2018 and 2019 from a field experiment conducted by the Department of Genetics, Plant Breeding and Bioresource Engineering. The highest total flavonoid content was found in the bark of S. purpurea UWM 166, whereas the total phenolic content and total antioxidant capacity were the highest for S. triandra UWM 197. The highest potential yield of total phenolic was obtained from S. americana UWM 094 and S. triandra UWM 197. The highest potential yield of total flavonoids was obtained from S. purpurea x S. daphnoides UWM 193 genotype. The content of bioactive substances and their potential yields were the highest in the second year of the study.