The study has been aimed at the development of technological methods that would help increase the propagation coefficient of improved source material of potatoes, obtained in meristem culture in vitro, grown in the primary seed production process.

The research has been based on the integrated use of field, laboratory, mathematical and statistical, computationally-comparative methods and systems analysis. In order to determine the most effective technological methods for the cultivation of improved source material in the primary seed production process, a two-factor experiment has been performed. The effect of different depth and density of microtubers spring planting on the potato productivity has been studied on the Kobza early- maturing variety.

Proved the maximum productivity of 24.2 c/ha (on the average by the factor) has been achieved with the nutrition area of 70 x 5 cm, the propagation coefficient being 1.1. With higher planting density up to 286,000 microtubers per hectare, the intraspecific competition increases, causing the decrease in plant productivity, that is, the number of microtubers, conducive to the propagation coefficient decrease. On average, long-term experiment testifies to the fact that the maximum productivity of 31.2 c/ha with the interaction of factors can be achieved with microtubers planted to the depth of 6 cm, the nutrition area being 70 cm x 10 cm, the propagation coefficient being 2.1. Increasing the depth of microtubers planting from 2, 4 cm to 6 cm improves yields on the average by 48.7 % and 45.6 % by the factor due to plant productivity growth by 36.7 % and 22.2 %, the total amount of microtubers increasing by 23.6 % and 25.7 %, respectively.

 In order to increase the propagation coefficient of improved potato source material obtained in vitro, microtubers spring planting to the depth of 6 cm and the nutrition area of 70 cm x 10 cm prove to be most economically efficient. In this case the profitability amounts to 262 %, the prime cost is 229 hryvna/kg of microtubers, net income comes to 1,155 thousand hryvna/hectare.

Key words: potatoes, southern Ukraine, primary seed production, nutrition area, the depth of planting, in vitro.