Study of water regime parameters in apples during drought

Relevance. Recently, the number of hot and dry years has increased significantly. Under the influence of drought, the leaves of the apple tree prematurely fall, the ovaries and fruits fall off, which significantly affects on the yield. In this regard, the study of the water regime of apple remains relevant under drought conditions.Methods. The studies were carried out on the basis of the laboratory of physiology of fruit plant resistance at VNIISPK in 2016-2017. Apple cultivars of the VNIISPK breeding growing on the semi-dwarf rootstock 54-118 were studied. Antonovka Obyknovennaya was taken as a standard cultivar. The experiments were laid in 2013, the spacing scheme was 5 m x 3 m. The crown shape is of spindle type. The row-spacing and near-trunk stripes are kept under the fall fallow. The method of artificial dehydration was used to determine drought resistance of apple cultivars. The apple cultivars were studied with the aim to determine the physiological parameters of water regime relative to their drought resistance.Results. As a result of the two-year studies, the cultivars were characterized by the average content of water in leaves (61.2-65.1%). Water deficiency in most varieties was optimal in the field and did not exceed 10.0%. The increase in water deficiency in apple leaves was noted in drought modeling. For two years, of the leaf tissues water deficiency was in leaves of the Veniaminovskoye cultivar both in the field (5.2%) and after drought modeling (22.4%). During the growing season, the distribution of precipitation and temperature during the passage of individual phenophases by apple plants influenced the overall water content in the leaf tissues. The decrease of the water content in the leaf tissues and the increase of water deficiency were observed when dry conditions occurred. The decrease of the water regime and water deficiency in leaves was notes to a greater extent during the formation of fruits. It was found that all of the studied apple cultivars had an average level of resistance to drought. The study of water regime parameters showed that Veniaminovskoye was characterized by more stable indices and this indicated greater resistance to drought.