Formation of the above-ground biomass of willow under the influence of varietal characteristics and the type of planting material

Abstract

Purpose. To reveal the regularities of the formation of the energy willow above-ground biomass structure and evaluate the qualitative and quantitative indicators of the biomass components under the effect of varietal characteristics and the type of planting material.
 Methods. Field experiments were conducted at the experimental field of the Institute of Bioenergy Crops and Sugar Beet (Ksaverivka 2, Kyiv region) located in the zone of unstable moisture in the central part of the Right Bank Forest Steppe of Ukraine in 2019–2022. Cuttings and shoots were harvested in autumn and stored in various ways until planting. In the spring, after planting the shoots in the open ground, the biometric parameters of plants were determined: plant height, stem diameter and the number of stems. The measurements were taken on the same day every month during the three years of the experiment. Two willow varieties were used in the experiment: Salix triandra L. variety 'Panfylska' and S. viminalis L. variety 'Zbruch'.
 Results. The intensity of growth of the above-ground biomass of willow, which also depends on the yield of planting material (cuttings or shoots), was determined by plant height, stem diameter and the number of stems. These indicators were higher in 'Zbruch' compared to 'Panfylska'. Thus, in the second year of vegetation, on the first date of measuring (in spring), the plant height of 'Panfylska' variety was 136.3 cm, while in autumn. on September 21, it was 242.8 cm. In 'Zbruch', the indicators were higher by 12.4 and 13.5 cm, respectively. A similar dependence was found when planting shoots. It should be noted that within one variety, no regular and reliable difference in plant height depending on the type of planting material was found. In the third year of vegetation, a similar dependence of plant height on varietal characteristics was obtained. On average, in 2021–2022, when planting willow cuttings of 'Zbruch' variety, plant height was 276.1 cm in the spring, while in 'Panfylska' it was 20 cm lower (256.1 cm). In autumn, plant height was higher in 'Zbruch' also by 20 cm. Depending on the year of vegetation, the increase in plant height was the greatest in the first year of vegetation compared to the second and third years. Weather conditions during the growing season affected the height of plants; However, in all years of the research it was higher when planting cuttings and shoots of 'Zbruch' compared to 'Panfylska'. No significant influence of variety and the type of planting material on the stem diameter and the number of stems was found in all years of the research.
 Conclusions. Plant height and diameter of stem in dynamics depended on varietal characteristics. In 'Zbruch' variety, when planting cuttings and shoots, the increase in plant height and stem diameter was higher compared to 'Panfylska' both at the beginning of the growing season and in autumn. During the three years of vegetation, varietal characteristics and the type of planting material (cuttings and shoots) showed no significant difference in the plant height, stem diameter and the number of stems.