GROWTH OF VEGETATIVE MASS OF ENERGY WILLOW IN THE SECOND GROWING SEASON DEPENDING ON THE TERM OF HARVESTING OF PLANTING MATERIAL AND APPLICATION OF ABSORBENT GEL

Abstract

This study aimed to elucidate the specific patterns in the development of biometric parameters in two energy willow (Salix L.) species within second-year vegetation plantations. The investigation specifically focused on the influence of two key factors: the timing of planting material (shoot) harvesting and the pre-planting treatment of cuttings with an absorbent. The research was conducted over a three-year period, from 2020 to 2022, at the experimental field of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Agrarian Sciences of Ukraine, situated in the Kyiv region. This location falls within the zone of unstable moisture characteristic of the Right-Bank Forest-Steppe of Ukraine. The object of the study was two types of energy willow: Salix triandra L. ‘Panfilska’ and Salix viminalis L. ‘Zbruch’. Every year, in the third decade of March – first decade of April, the plantations were established with standard cuttings 20–25 cm long and 2.0–2.5 cm in diameter with three to four well-developed buds. During the growing season, the following biometric parameters were determined monthly: average plant height (cm), stem diameter (mm), number of stems per bush (pcs.). Statistical processing of the results was carried out using analysis of variance to determine the reliability of differences between the experimental variants. The findings of this investigation demonstrated a statistically significant impact of both the planting material harvesting period and the application of a gel-absorbent on the development of biometric characteristics of the energy willow plantations during their second year of vegetation. The study revealed that the number of surviving plants, as well as the height and stem diameter of the energy willow, exhibited dependence on varietal characteristics when assessed dynamically throughout the growing season and averaged over the threeyear study period. Furthermore, the application of the gel-absorbent exhibited a differential effect based on both the variety and the harvesting period. Specifically, the use of the gel-absorbent promoted an increase in plant height and stem diameter in the ‘Panfilska’ variety when shoots were harvested in autumn. Conversely, in the ‘Zbruch’ variety, a more pronounced growth in these parameters was observed with spring harvesting in conjunction with the gel-absorbent treatment.