The knowledge of crop response to different amounts of water is essential in order to plan and manage the water resources, especially in areas where water supply is limited.
Mature apricot trees (Prunus armeniaca L. cv. 'Búlida') grown under drip irrigation conditions were subjected to four irrigation treatments over 4 years. Control treatment (T1) was irrigated at 100% of estimated crop evapotranspiration (ETc) throughout the year, a continuous deficit treatment (T2) at 50% of the control, and two regulated deficit irrigation (RDI) treatments (T3 y T4) at 100% of ETc during the critical periods and with deficit irrigation for the rest of the year. These treatments involved water savings of around 40 and 20% in the first two and the last two seasons, respectively. The average irrigation amount applied to the control treatment was 7000 m³ ha^‑1 year^-1.
The effects of the irrigation treatments on growth and yield of apricot trees are discussed in relation to the water deficits applied. An important reduction of the yield was accomplished when water saving was between 30 and 45%, a consequence of the reduction of the number of fruits for tree. With water savings between 15 and 20% the total production was similar to the control treatment. The treatment irrigated at 50% reduced the yield in all years of study. However, the quality of the apricot was not affected by deficit irrigation. As a consequence, RDI scheduled with moderate water savings in phenological periods less sensitive to deficit, constitutes a useful irrigation strategy for apricot trees in situations of limited water resources.