Yield formation of the sweet cherry (Cerasus avium L.) intensive orcards depending on interstem VSL 2 length in the Ukraine’s Southern Steppe

Abstract

The comparative evaluation of the predicted (biological) and actual yields of the sweet cherry Valerii Chkalov and Melitopolska Chorna, grafted on the interstem VSL 2 (the main rootstock is Mahaleb seedlings) was carried out in the intense orchards under the conditions of the Southern Steppe of Ukraine. The trees with the interstem VSL 2 length 30 cm appeared to be characterized by the highest spur density, displaying an increase by 19 and 11 %, as compared to tress with the interstem length 20 cm (control) and 50 cm respectively. Cv Melitopolska Chorna on the 2-4-year-old wood had the 1.3-1.6 times higher spur density than ‘Valerii Chkalov’. The analysis of the total number of spurs per tree showed that for VSL 2 length 20 and 30 cm, this index was, on the average, 1233 and 1252 pcs./tree respectively. Only when the interstem length increased to 50 cm, there was a decrease in the number of spurs per tree by 23 %. That can be explained by the reduction in vigour of the trees in this variant. The studied varieties proved to react to the change of VSL 2 length in different ways: the average yield of the ‘Valerii Chkalov’ – trees in 2014-2018 in the variants with the interstem length 20 cm (control) was equal to that with the length 30 cm – 8.9 and 9.0 t/ha respectively, but than lower with length of 50 cm – 8.6 t/ha. The trees of ‘Melitopolska Chorna’ with the interstem length 30 cm showed the highest yield – 10.1 t/ha. That surpassed the control variant by 26 %. The decrease of the yield in the variant the VSL 2 length 50 cm on the both studied strains can be explained by the lower vigour causing fewer amount of the spurs formed on a tree. In the conditions of the Southern Steppe of Ukraine the intense sweet cherry orchards during the years with the favourable weather conditions, turned out to be able to apply their productivity potential by 69-78 %.