The drought-resistance of 15 nectarine varieties and forms with a sign of male infertility is studied. The research identified genotypes with varying degrees of drought-resistance. The greatest degree of drought-resistance demonstrated the form 33-3-1, 512-86,41-15-2, and grade Kul'dzhinskiy 4x, Krymtsuht, Elbertaziya.

Morphological and cultivation value characteristics description of new perspective ornamental peach varieties bred in Nikita Botanical Gardens has been given. The varieties were bred as a result of using genoplasm Persica vulgaris Mill, varieties with different type of flower, P. mira (Koehne) Koval, et Kostina and Amygdalus communis L. They differ in high ornamental idices in flowering period and in bioecilogical indexes.

There are allocated some forms of distant hybrids with weak degree of fungal diseases lesion (Taphrina deformans (Berk.) Tul., Sphaerotheca pannosa (Lev.) var. persicae Woron., Clasterosporium carpophilum Aderh., Monilia cinerea Bonord. и Monilia fructigena Fr.) that are of practical interest for breeding such cultivars of peach and nectarine that will resist these pathogens.

The varieties and forms of nectarine resistant to fungi diseases (Clasterosporium carpophilum (Lev.) Aderh., Taphrina deformans Tul., Sphaerotheca pannosa (Wallr.) Fr. Lev. var. persicae Woronich) having the practical interest for modern technology growing and for breeding on these characteristics have been selected.

The perspective hybrid forms between genus Prunus persica (L.) Batch and Prunus amygdalus Batsch, having high ornamental qualities and high resistance to Sphaerotheca pannosa (L v.) var. persicae Woronich., Taphrina deformans (Berk.) Tul., Clasterosporium carpophilum (L. v) Aderh., Monilia cinerea Bonord. have been obtained for using in breeding of peach and nectarine varieties and their rootstocks.

The article mentions that 113 peach hybrid forms resistance to drought, to leaf curl infection Taphrina deformans Tul. and powdery mildew Sphaerotheca pannosa Lev. var. persicae Woronich have been obtained in the result of their studying. One of the most important agronomic sigh is a drought- resistance. Elite forms assessment on this indicator has been carried out in the most drought year during the last50 years. 23 forms with high drought-resistance have been selected. The leaves curl and false mildew are considered to be the most harmful fungal diseases reducing the plants peach vitality and leading to their lethality. Infection assessment has been carried out according to the average annual dates, and in epidemic (epiphytotic) year with a maximum disease revealing. As a result 14 hybrid forms infected by low leaves curl and 16 – by false mildew have been selected. According to the varieties characteristics complex 15 ones have been selected. Most varieties identified by their drought-resistance have belonged to the North Chinese eco-geographic group (59,1%), by a low leaves curl infection (Taphrina deformans Tul.) to the Iranian eco-geographic group (64,3%); by the false mildew (Sphaerotheca pannosa Lev.) to the Northern Chinese eco-geographic group (54,3%). The selected varieties perform the interest as sources of important mentioned economic valuated characteristics and they can be used in breeding.

The pomological description of studied samples has been given; the chemical composition and relation between biochemical characteristics in fruits of Prunus cerasifera subsp. macrocarpa (Erem. et Garcov.) var. pissardi Bailey has been studied. The obtained data are compared with characteristics, typical for fruits of varieties Prunus cerasifera Ehrh. and forms of Persica vulgaris subsp. atropurpureae (Schneid.) Zajats.

Firstly in Ukraine as the result of resiprocal interbreedings of autotetraploid (2n=4x=32) / diploid (2n=2x=16) and diploid (2n=2x=16) / autotetraploid (2n=4x=32) four sintetic triploid (2n=3x=24) hybrid forms (611-91, 13-93, 14-93, 18-93) have been obtained. Spontaneous triploid nectarinum 166-80 has been shared out from diploid hybrid seedlings population. Tetraploid and triploid nectarinum forms are valuable sources for directoinal selection and making hybrids with the complex of new signs, which are difficult or impossible to receive on diploid level.

The studying results of drought resistance for introdused nectarine varieties in the conditions of South Coast of the Crimea have been given. Four varieties shoved high resistance to drought conditions during two years have been selected.

Created in Nikitskyi botanical garden Remote hybrids of nectarine and peach with almond ordinary can be used in Breeding of nectarine and peach fok high resistauce to fundi, as wengs for creation of varieties of nectarine with high drought resistance, sweet seed kernels, high contents of organic substance, and other important Breeding characteristics. Late blossoming hybrid forms can be used in Breeding of almond fok late time of flowering and selfcompatibility.