The article deals with the issues of peculiarities of the formation of miskanthus uterine rootstocks mass and the rhizomes yield depending on the quality of the planting material – the number of buds on the rhizomes planted. It is found out that the more buds are on the rhizome, the higher is the percentage of their survival, the more intensive is the increase in the surface mass – the plants height, the number of leaves and the leaf surface area, which contributes to the increase in photosynthesis productivity and affects not only the crop yield but also the root system increase, i.e. the planting material yield.

Direct strong correlation between plant height, leaf area, leaves number, number of buds on rhizome and rhizome mass were found. The coefficient of correlation for planting rhizomes with 1-3 buds was 0.85, 1.00, 0.71 and 1.00, respectively. An increase in the surface mass contributed to the increase in the rhizome mass growth, and, accordingly, to the planting material – rhizome – yield.

It was found out that planting rhizomes with 9 or more buds, the mass of uterine rootstocks (1409.1 g) was the largest, or 2.86 times higher than in the control. The increase in the rhizome mass and its crotch degree contributed to the formation of a larger amount of buds and the yield increase in both small and large rhizomes. Planting the rhizomes with 4-8 buds, the mass of rhizomes was also significantly higher than in the control, but it was significantly lower than the mass of uterine rhizomes were obtained under planting rhizome with 9 or more buds. Studying the factors influencing the mass of uterine rhizomes reveal that the share of " rhizome quality – buds number" factor effect on average for three years was significant and made 64.8 %.

The variability of uterine rhizomes mass in three years reproduces the phenotypic character of this trait, where, under planting rhizomes with 1-3 buds (control), the average of 87.5 % of uterine stock weight up to 500 g, and 12.5 % of rhizomes weight 501-700 g. The variation between the extreme indices ranged from 317 to 751.0 g with an average value of 533.4 g. For the rhizomes planted with 9 or more buds, 87.5% of uterine stock weighted more than 1300 g and only 12.5 % of them weighted 1101-1300 g with the variation of the index ranging from 1115 to 1963 g for an average value of 1541.2 g. That is, planting the uterine plants with a larger amount of buds on rhizomes not only increase the uterine weight, but a deviation in their minimum and maximum weight as well, indicating the phenotypic changes in this index. The buds were formed more on the larger rhizomes. 105.2 buds were formed on the rhizomes planted with 1-3 buds (control) weighing of 493.1 g, while for the rhizome planted with 9 and more buds with the weight of rhizomes of 1409.1 g there were 239.7 buds, or 2.3 times more. For planting rhizome with 4-8 buds on rhizomes also formed considerably more kidneys than in control but less than in the variant, where planted rhizomes with 9 and more kidneys. On the number of kidneys on the uterine rhizomes, as well as their weight, had a significant effect the factor "quality rhizomes - the number of kidneys", which was 48.1 % on averaged over three years, the influence of the factor "the condition of the year" was also significant and amounted to 38.1 %. The increase of the mass of the rhizomesand its degree of branching are provided for the formation a greater number of kidneys and an increase in the yield of both small and large rhizomes. For the use of rhizomes that has 9 or more kidney buds that have been formed on average for three years, it is possible to obtain of 2.3 times more small or large rhizomes compared to the control where rhizome was planted with 1-3 buds. Gardening with rhizome with 4-8 buds is provided the formation of rhizome from which you can get 1.6 times more than in the control and in 1,4-1,5 times less than rhizome planting of large rhizomes with 9 or more kidneys.

Key words: uterine rhizomes, buds number, variability of rhizome mass, quality, correlation.