Biomass accumulation is a complex mechanism which shows a complicated relationship of apple-trees with environmental conditions and main agro technical factors. The efficacy of the relationship proves yielding capacity level and total phytocoenosis productivity. New rootstock types and intercalations which explain intensive designs of apple tree orchards are studied in modern horticulture.

Phytomass increase correlates with a fruit tree age, and during ontogenesis the accumulation occurs due to lateral branching and considerable reduction of an apical growth. It has been recorded, that sprout rather than rootstock plays an important role in a monthly rate of phytomass increase. It has been proved that architectonics and phytomass structure depend on cultivar peculiarities, a rootstock type, an application of various pruning terms.

We set a task to identify the effect of a rootstock type, intercalary insertion, planting density and pruning terms on phytomass increase of the apple trees under the conditions of the Forest-Steppe Zone of Ukraine.

The experiments were carried out at the department of fruit production and viticulture of Uman national university of horticulture in 1991-2010 (the university is located in the Forest-Steppe Zone of Ukraine). Trial 1 was planted by Professor H.K. Karpenchuk in spring of 1981; one-year-old Idared and Melrose trees of Yugoslavian production were planted on rootstocks M.9, MM.106 with a 4-m row. The spacing for young trees on rootstock M.9 was 1,5, 1,75, 2,0 m (thickening, 1667, 1430, 1250 trees/ha respectively), and that on ММ.106 – 1,75, 2,5, 3,0 m (1430, 1000, 833 trees/ha). Trial 2 was laid by the author of this paper in spring of 1989; planting scheme was 5х3 m, young trees of Rubinove Duky and Idared cultivars and intercalary inserts of vegetative rootstocks М.9 and ММ.106 (various vigor levels) were used. Control trees were grafted on vigorous Antonovka rootstock. Two pruning terms of the trees under study were applied: winter and summer. A type of a crown was a slender spindle. Winter pruning (“winter”) was performed using traditional industrial technology. Time for summer pruning (“summer”) was determined when the beginning of an active differentiation of a growing-point in experimental variants was observed. P.Ye. Shumylo’s technique was used to define phytomass increase.

In trial 1 phyto-mass increase (PI) of Idared trees on a dwarf rootstock M.9 when they reach the age of 10-12 years was insignificant and ranged 0.5–1.0 kg/tree, which is due to abundant yield in this period (up to 14.3 kg/tree).

In the following years PI increased, but it fluctuated in different years, PI reduction correlating with the increased yield load of the tree. Idared trees on MM.106 rootstock had higher indicators of PI, however at the age of 10-12 PI reduction had a similar tendency as in the case of growing on M.9 rootstock. A 12-year-old period has to be emphasized, during this period PI reduction was recorded –
1-2 kg/tree, which is explained by steep yield increase during this period.

In the years of experiment in trial 1 planting density (PD) had a considerable effect on PI only when rootstock MM.106 was used  and this can prove an optimal choice of planting scheme for dwarf rootstock M.9 and the establishment of a possible margin limit when trees are densely planted in a row and MM.106 rootstock is used.

Based on disperse analysis data, a dominating effect of a tree age on PI (67%) is recorded, but quite a sufficient effect of a rootstock type is observed (14%). Planting density had an important effect only when trees were grown on rootstock MM.106 (5%).

According to the research results in trial 2, PI depended on variety specific features, an insertion type and pruning terms of apple trees. PI increased till the eighth vegetation and was much higher in vigorous cultivar Rubinove Duky (up to 9.2 kg/tree). PI decreased considerably in vegetations 9-10 in all variants (cultivars Rubinove Duky and Idared) which was due to unfavorable phyto-sanitarian conditions of the plantations.

Idared trees had the highest indicators of PI, up till vegetation 8, in variants when seedling rootstock was used both under summer and winter pruning, and in combination with insertion M.9 – till vegetation 9 and winter pruning. Thus, winter pruning enhances PI of apple trees when they are grown on weak vegetative insertions.

Based on disperse analysis data, an insertion type had an important effect on PI (41% - Idared, 40% - Rubinive Duky); the age of the trees was of great significance (29% - Idared, 32% - Rubinove Duky).

The cultivation of apple trees on a seedling rootstock enhances phytomass increase, whereas weak intercalary insertions reduce it considerably. As the tree gets older, phytomass increase gets slower, depending on a rootstock type, a pomological cultivar and a pruning term.

Key words: apple tree, intercalary insertion, phytomass.