Dependence of apple productivity and fruit quality on the method of drip irrigation terms appointment

Modern fruit growing involves the use of drip irrigation systems. The methodology for diagnosing of drip irrigation terms appointment and calculation of irrigation rates require continuous improvement on the basis of the introduction of measuring instruments. These issues are relevant for the commercial fruit growing of the world's most common perennial crop - apple trees (Malus domestica Borkh). The purpose of the experiment was to optimise drip irrigation regimes and to analyse the evapotranspiration (ET) of an apple tree depending on the methods of drip irrigation terms appointment. For comparison, four methods were applied: 1) the digital iMetos ECO D2 soil moisture station, 2) the tensiometric method, 3) the Penman-Monteith calculation, and 4) the visual method. The control was irrigation-free treatment. The results of the experiment confirmed the effectiveness of the use of drip irrigation for the cultivation of an intensive apple orchard at the Steppe of Ukraine. According to the parameters of the drip irrigation regime and the yield of apple trees, the use of the iMetos ECO D2 soil moisture station was determined as the most effective method of drip irrigation terms appointment. In this treatment, the irrigation rate was 650 m(3) ha(-1), the crop evapotranspiration (ETc) value 3.25 thousand m(3) ha(-1), the water consumption coefficient 83.4 (3) t(-1), the irrigation efficiency 20.7 m(3) t(-1), and the marketability of apples was 93%. It was found that the removable fruit ripeness parameters: tissue density, sugar content, and degree of starch degradation, were within the sanitary norms of apple quality. This method is defined as the most water-saving, based on the experimental data on irrigation rate and crop productivity. Thus, it is recommended for the use in apple production in the South of Ukraine.