Productivity of black poplar depending on the age of the plantation

Abstract

Aim. To investigate the influence of the age of the plantation on the formation of productivity and quality indicators of raw materials of black poplar plants, which ensures maximum yield of above-ground mass. Methods. Laboratory, measurement, calculation and comparative, analysis, statistical. Results. At the beginning of the growing season, the dry matter content in poplar leaves ranged from 34.1 % (plants planted in 2018) to 42.3 % (plants planted in 2020). In July, the amount of dry matter increased and amounted to from 40.3 % to 44.9 % (2018 and 2020). During the active growing season, the highest dry matter content in the leaves was in plants planted in 2018, namely 48.7 %, the lowest content was 45.0 % in plants planted in 2020. The stems of the studied plants at the beginning of the growing season accumulated from 47.3 to 49.1 % of dry matter, and the maximum values of this indicator were provided by the plants at the end of the growing season, namely from 64.8 to 66.4 %. The amount of ash elements in poplar stems at the beginning of the growing season was from 1.7 % to 2.0 %, then this indicator changed and was from 1.8 to 2.5 %, and at the end of the growing season from 1.9 to 2.5 %. Conclusions. The dry matter content in the leaves of black poplar was higher than in the stems and both in the leaves and in the stems did not depend on the age of the plantations. The amount of ash elements in the leaves was higher compared to the stems, more ash was observed in plants with a longer growing season. The accumulation of cellulose and hemicellulose in poplar leaves occurred as follows – a greater amount of cellulose is observed in the leaves of plants with a longer vegetation period. The amount of cellulose and hemicellulose in the stems of black poplar was greater than in the leaves, and the amount of cellulose and hemicellulose increased depending on the age of the plantations. Analyzing the accumulation of nitrogen, phosphorus and potassium by the leaves and stems of plants, we note that a greater amount of nitrogen and phosphorus is in plants with a longer vegetation period. The increase in the accumulation of nitrogen, phosphorus and potassium in the leaves and stems occurs gradually during the vegetation period and reaches maximum values in August. The accumulation of chlorine and sulfur by the leaves and stems of black poplar occurred similarly to the accumulation of macroelements, namely a greater amount was noted in the leaves, a smaller amount in the stems, and the amount of chlorine and sulfur was noted in plants with a longer vegetation period.