Drought stress affects productivity and fruit size of new apple cultivars

Growing apples in some regions may be restricted due to drought since the apple is a crop sensitive to drought stress. It is necessary to supply enough water in orchards during the critical period, more specifically during the development of the fruit. Otherwise, the lack of water would result in a reduced yield. To ensure fruit quality and yield, it is better to prevent drought by irrigation. However, water is not an unlimited resource. Therefore, this work deals with the evaluation of the production of several apple cultivars under reduced water supply. Growth and yield parameters were evaluated in 14 apple cultivars with ‘Golden Delicious’ used as a control. Trees were grafted on M 9 rootstock and planted at a density of 2272 trees ha^‑1 in Eastern Bohemia (Czech Republic) in 2014. The trees were left without an irrigation system. The date of flowering was recorded for each single tree and the girt of trunk was measured at the end of the vegetation to determine the trunk cross-sectional area at height of 0.6 m. Fully matured fruits of each cultivar were harvested. The total yield of each tree was recorded, the specific productivity was calculated, and the fruits were divided in 4 size factions (<65 mm, 65-75 mm, 75-85 mm, >85 mm). Cumulative yields in apples ‘Topaz’, ‘Artiga’, ‘Flordika’, ‘Frosta’, ‘Reluga’, ‘Gala’, and ‘Rucla’ were significantly higher compared to LSQUOGolden DeliciousRSQUO. These cultivars appeared to be better suited for growing upon conditions of absent supplemental irrigation.