According to sugar beet yield formation during the periods of intense roots growth, the value of daily sugar increments in them – is very high. With the slowdown in root growth the dry weight and daily sugar increments is reduced. But in the period of growth processes inhibition under the influence of unfavorable weather conditions are not always observed termination of sugar growth in the roots. Change of sugar content in the raw mass of sugar beet root during the growing season is in the opposite direction of the change of water content in it; the ratio of these substances is constantly changing during the growing season of crop.

Earlier studies are proved that the sugar content of roots depends primarily on the length of the period of active growth and development, and sucrose may be the only component through which the end of the growing season there is an increase of dry weight of roots.

The sugar accumulation in sugar beet goes continuously, slowly at the beginning of sugar accumulation and more intense – in the second half, at the end of the growing season is slowing. The increasing pace of sugar accumulation is coincides with the formation of the largest leaf area of crop and fastest of plants growing.

Experimental researches were conducted on the experimental field of Bila Tserkva National Agrarian University during 2010–2012. Technology of sugar beet growing on test plots was common for the forest-steppes of Ukraine, except for the elements that were studied.

Total area was16.2 m², accounting – 13.5 m², repetition – 4-thou-time. For research are used sugar beet diploid pelleted seed hybrids: Ukrainian ChS 72, Leopard, Zoom and triploid hybrid pelleted seed: Umansky ChS 97, Oryx, Murray.

Over the research years on intensity of leaves formation, growth and development of roots is influenced not only the field germination, varietal composition but also weather conditions during the growing season. The share of weather conditions influence was 73 %.

In average of research years the daily gain of root mass held in July and August most intensively, which coincided with the most intense of leaf apparatus increase.

The growth of root weight is depending on biological forms of sugar beet held differently depending on the phase of plant development. Thus, from sowing to the beginning of September intensely growth of roots mass held in triploid hybrids and from September to harvesting – on the contrary in diploid hybrids of both domestic and foreign origin. In addition, hybrids of foreign selection of both biological forms is differed the intense of roots mass growth in autumn from September prior to harvesting, compared with hybrids of domestic origin.

In average of research years there is a tendency intensive gain weight of roots both biological forms of hybrids of domestic origin in August compared with foreign, and hybrids of foreign selection is differing the intense of roots mass growth in the autumn from September prior to harvesting. The intensity of roots mass growth and leaf surface depends on the provision of plant by moisture regardless of biological forms of beet and their origin. According to optimal or excessive moisture plants growth and development are satisfactory both of domestic and foreign origin and even with a slight deficit of moisture this process is slow down and leaf apparatus is fades regardless of the phase of plant development.

Research has established the regular increase of sugar growth in the roots of both biological forms of sugar beet. On average of research years during the growing season, from early July to September sugar content increase in diploid forms was
5.8 %, triploid – 6.0 %.

There were not significant differences depending on the biological forms.

Most intensive sugar is accumulates in the roots in July and August, regardless of hybrids of both biological forms of sugar beet, which coincided with the most intensive growth of root mass and leaf apparatus mass accumulation.

The average of three years the dynamics of the sugar content is gradually increasing to 0.8-2.5 % from one account date to another, regardless of biological forms of sugar beet. There was no significant difference on the dynamics of sugar accumulation in the root, depending on the varietal composition of hybrids.

Key words: sugar beet, biological forms, the dynamic of leaf apparatus growth, the dynamic of root mass growth, sugar content.