The cultivation suitability assessment of summer apple varieties by intensive technology in the arid zone

The purpose of research is to study the introduced varieties of apple trees according to the main economically valuable indicators and to identify the best ones for creating intensive plantations in the semi-desert zone of the Northern Caspian Sea. The objects of study are 4-year-old apple varieties: Iyul'skoe, Mantet and Kvinti, grafted onto a medium-sized clonal rootstock 54-118. The variety Uelsi, zoned in the Astrakhan Region, was taken as control. Trees were planted in autumn 2018 using intensive technology on an area ofha according to a scheme of 5.0 × 2.0 m (1000 trees/ha). In a one-factor experiment, each variety was planted with 45 trees. All counts and observations were carried out on 10 typical trees of each variety in triplicate. The results of the study of new promising apple varieties according to the main economically valuable indicators (biometric growth parameters, drought and heat resistance, precocity and productivity) when grown under conditions of insufficient moisture and high thermal stress in the arid zone of the Northern Caspian Sea are presented. The trees of the Uelsi and Kvinti varieties (2.4 m) grew most powerfully in height, the Mantet variety (1.9 m) provided the trees with restrained growth. The maximum values of the crown projection area relative to the control were recorded in the Kvinti variety (0.9 m2), the Mantet variety (0.4 m2) was characterized by a weak development of this indicator. The Iyul'skoe variety was characterized by a high level of drought resistance, and the Uelsi variety was characterized by heat resistance. The productivity of varieties varied on average from 1.0 to 2.5 kg/tree. The largest fruits were formed in the control variety Uelsi (227.0 g), which surpassed the other varieties of this group by 29.5-42.7 %.