EVALUATION OF APPLE PLANT VARIETY COMBINATIONS IN THE CONDITIONS OF THE FOREST STEPPE OF THE RIGHT BANK OF UKRAINE
Authors: Vdovenko Serhii , Palamarchuk Inna , Tarnavska Kateryna 
Published: January 2024

A study on the impact of varietal rootstock combinations on the productivity of apple trees was established at the research station of horticulture of the Institute of National Academy of Sciences of Ukraine in 2013-2014 with 17 new and promising clonal rootstocks for apple trees. At the same time, Amulet, Askolda, Renet Simyrenko, Revena, Ligol, Todes, Jonagored varieties were used as grafts. The growing season of fruit trees began and ended depending on weather conditions. The beginning of vegetation of apple varieties on rootstocks was observed in the first decade of April, and in 2017 and 2020 in the third decade of March. During 2016-2020, the difference between varieties in the rate of bud break was 1-4 days. Flowering of the trees began at the end of April at the beginning of May and lasted for 9-11 days, depending on weather conditions. Over the years of research, an earlier flowering period was characteristic of Askold and Ligol varieties, and in most varieties the flowering phase began on May 2-4.

The characteristics of the growth processes of fruit trees of apple trees indicate a direct dependence of the strength of the growth of the tree and the rootstock. In the Revena variety, planted in 2013, the largest increase in the cross-sectional area of the stem was determined in combination with control rootstocks M 9 - 2.71 cm2, 54-118 - 8.32 cm2 and MM106 - 8.40 cm2. In the Askold variety, in the group of dwarf rootstocks, trees in combination with the control rootstock M 9 - 3.10 cm2, with the semi-dwarf rootstock K104 - 9.31 cm2, and on medium growth from the rootstock D 471 - 7.43 cm2 were stronger.According to the Jonagored variety, planted in 2014, a higher researched indicator was established in combination with the dwarf rootstock KD 4 - 3.56 cm2, on the semi-dwarf rootstock 54-118 - 5.58 cm2, medium-growing rootstock D1904 - 7.10 cm2.

According to the indicators of the total growth of shoots and the average length of shoots, stronger growth was noted in the group of dwarf rootstocks in the varieties: Revena, Askolda, Renet Simyrenko, Amulet in combination with rootstock M9. Also, with the use of semi-dwarf rootstocks, a stronger growth of one -year shoots was noted in the varieties: Revena in combination with the control rootstock 54-118 – 53.2 cm, Amulet, Renet Simyrenko, and Askolda with rootstock K 104, respectively 60.9 cm, 67.5 cm, and 73.2 cm, on a medium-sized rootstock, the strongest growth was noted in all varieties of apple trees in combinations with D 1904 rootstock.

The volume of the crown of the tree depended on the pomological variety and rootstock. From the use of dwarf rootstocks, a larger crown volume was noted in the varieties Amulet (5.0 cm3), Renet Simyrenko (8.4 cm3) with the control rootstock M 9, in the variety Revena (1.92 cm3) with the rootstock KD 4, in the variety Askolda (3.3 cm3) with rootstock D 3038 and on a semi-dwarf rootstock - in varieties Askolda (12.7 cm3), Renet Simyrenko (14.28 cm3) with rootstock K 104.

In terms of yield, the highest indicator was the Revena variety on rootstocks M 9 - 15.7 t/ha, 54-118 - 11.5 t/ha and MM 106 - 9.8 t/ha. At the same time, a higher fruit yield of the Askold variety was obtained in combination with dwarf rootstocks D 1071 - 13.7 t/ha and D 3038 - 13.8 t/ha and in the variant with the M9 rootstock, where the value was 13.0 t/ha and with a medium-sized control rootstock MM 106. Thus, for the Renet Simyrenko apple variety, the highest yield was recorded in combination with the D 1071 dwarf rootstock - 11.1 t/ha, which was 21% higher than the M 9 rootstock, and in combination with the semi-dwarf Baturyn rootstock, the yield decreased and amounted to only 3, 5 t/ha, Slobozhanska - 3.3 t/ha and D 1161 - 6.8 t/ha. One of the indicators of marketability of the crop is the average fruit weight. The average weight of the fruits in the variety rootstock combinations was the largest in the trees of the control variety rootstock combination, namely: M 9, 54-118, MM 106, and already in the varieties planted in 2014, the highest average fruit weight was obtained with dwarf rootstocks D 1071, D 3038 . However, in combinations with Revena, Amulet, and Todes varieties with rootstocks Sambirska, D 1071, fruits of the highest and first varieties prevailed - 92.2-93.0%