Abstract: We analyzed the variability of agronomic characteristics, yield, and quality of apples with different ripeness and explored the dominant role of moisture regulation in apple cultivation in southern Xinjiang, aiming to provide theoretical basis for developing irrigation regime for different varieties of apple. The experiment was carried out in 2020 and 2021 in dwarf-stock dense apple orchards of Regiment 10 in Alar. Five irrigation levels \[13.5 mm (W₁), 18 mm (W₂), 22.5 mm (W₃), 27 mm (W₄) and 31.5 mm (W₅)\] were set for the test varieties Royal Gala and Fuji of five and six years old, respectively. The indices of agronomic traits, water consumption characteristics, yield and quality of apples were measured. The results showed that irrigation quota had a significant effect on apple shoot and fruit diameter. The length of new shoots increased with increasing irrigation quota, but fruit diameter was inhibited. For apple trees of different ripeness, water consumption and crop coefficient of each phenological stage were in the order of fruit expansion>fruit ripening>flowering and fruit setting, with a peak at fruit expansion. Among the various irrigation treatments, Fuji and Royal Gala had the highest yield in treatments W₃ and W₄ respectively. W₃ was the treatment with the highest water use efficiency. Fruit hardness, starch index, sugaracid ratio, and soluble solid content of Fuji and Royal Gala in treatment W₁ were superior to those of the other treatments. Fruits from the treatment W₃ had the highest water content. Hardness and the content of soluble solids were strongly correlated with water use efficiency. The comprehensive analyses on agronomic traits, water consumption, yield and quality of apples of different ripeness as well as the economic benefits showed that the suitable irrigation quota for Fuji and Royal Gala was 22.5 mm, and that the frequency of irrigation was 23 and 20, respectively.

Key words: moisture regulation, southern Xinjiang, yield, quality, water use efficiency, overall evaluation.