FORMATION OF QUALITY OF VEGETATIVE MASS OF ENERGY CROPS OF DIFFERENT VEGETATION DURATION

The research results show that in the samples of switchgrass plants with different vegetation periods the dry matter content varied from 52.40% in the leaves of the 3rd year of vegetation to 77.15% in the leaves of plants of the 8th year of vegetation. In the leaves of miscanthus, the dry matter content varied from 59.35 to 62.30% depending on the duration of the growing season. This figure for energy willow was in the range of 61.23–66.12%. There is a general trend in the content of raw ash in various plant organs: more in the leaves and less in the stem in all variants of the studied plants. Thus, the ash content in switchgrass plants ranged from 1.2% in the stems of plants of the 8th year of vegetation to 4.5% in the leaves of plants of the 10th year of vegetation. The ash content in miscanthus plants ranged from 1.6% to 3.0%, and in willow samples - in the range of 1.9–3.5%. The accumulation of hemicellulose in bioenergetics plants occurs gradually during the growing season. In particular, a slightly higher content of hemicellulose was observing in the stems of bioenergetics plants, less in the leaves. Thus, in switchgrass plants the highest content of hemicellulose was in the stem – 22.65%, and in the leaves 22.75%. In miscanthus plants, the hemicellulose content in the stem ranged from 21.51 to 22.55%, and in the leaves from 21.49 to 22.30%. With regard to energy willow, the distribution of hemicellulose in the plant varied like switchgrass – less in the leaves and more in the stems. The accumulation and distribution of cellulose in bioenergetics plants was similar to hemicelluloses, the leaves were smaller comparing to the stems. In switchgrass plants, the highest cellulose content was in the stems – 42.03–45.49%, and in the leaves – 42.08–45.33%, depending on the duration of the growing season. The distribution of cellulose in switchgrass and energy willow plants changed similarly. Young plants have little lignin, but with age its amount in the tissues increases significantly. Plants accumulate the most lignin in the spring and less in the fall. The accumulation of lignin in samples of bioenergetics plants was different. Its greater content was in the leaves, and less in the stems. Thus, the plants of switchgrass had the highest amount of lignin in the leaves – 18.59% (plants of the 10th year of vegetation), the lowest in the leaves – 15.92% (plants of the 3rd year of vegetation), and in the stems, respectively, 18.02 and 15.90%.