P. Kaymakanov*

Department of Fruit Growing, Faculty of Viticulture and Horticulture, Agricultural University Plovdiv, 12 Mendeleev, 4000 Plovdiv, Bulgaria

Abstract. In the period 2012 – 2013 the influence of 3 interstocks on growth and fruit bearing of the sweet cherry cultivar Biggareau Burlat grafted on Prunus mahaleb L. – P1 seedling rootstock was tested. As interstocks were used Gisela 5, the sour cherry cultivar North Star and the Hybrid 2/10, each of them with length 10 and 30 cm. The trees were planted in March 2006 with planting distance 6.0 x 4.5 m and were grown without irrigation and training. The sweet cherry cultivar Stella which was planted in adjacent rows was used for pollination of Biggareau Burlat. It was established that under the influence of the longer intesrock the trunk size was reduced in the area of the rootstock and the interstock itself. The trunk size was bigger in the area of the scion. The differences were more pronounced where Gisela 5 was used. The longer interstock induced weaker growth of the trees grafted on Gisela 5 and reduced the crown volume. The trees with the longer interstock have larger number of blossoms per linear metre of two-year-old wood, but with lower percent of fruit set. Despite the lower fruit set the trees with the longer interstock have higher cumulative yield compared to the crown volume and the differences to Gisela 5 are proved.