Institute of Highland Animal Husbandry and Agriculture, BG-5600 Troyan, Bulgaria
MINEV, I., 2001. Preliminary results of the study of between-species hybrid 70/3 (P. spinosa x P. cerasifera) with characteristic peculiarities of P. domestica species. Bulg. J. Agric. Sci., 7: 409-413
Between-species hybrid 70/3 has a comparatively early flowering, usually at the beginning of April. Flowers are considerably bigger than those of blackthorn with an average diameter of 21.2 mm. Fruits are dark blue with purple shade. They are elliptic and have the following dimensions: height – 26.4 mm, width – 24.6 mm and thickness – 23.8 mm with a mass of 8.2 g. Their chemical composition is as follows: total sugar content – 8.85 mg %, acids – 1.34 mg % and tannin content – 0.381 mg %. The stone weight is 0.81 g and is difficult to detach. Leaves are comparatively large, those of stem branchlets with a length of 60.5 mm and width 28.4 mm. Trees have moderate growth capacity. The hybrid considerably exceeds the maternal form, i.e. blackthorn, in terms of crown volume and trunk diameter but its growth capacity is considerably lower than that of cherry plum. The morphological and agrobiological characteristics of the between-species hybrid 70/3 are similar to the representatives of P. domestica. It is also interesting from immunobiological point of view as a primary form in selection of cultivars with improved resistance to fungal diseases, tolerant to plum pox.