Effects of regulated, precision and continuous deficit irrigation on the growth and productivity of a young super high-density olive orchard

Water is the main limiting factor for olive cultivation in rainfed conditions. In irrigated orchards, water avail-ability is scarce mainly during drought periods. Thus, increasing irrigation efficiency is a key issue to improve water management, especially in semiarid conditions. The objective of this study was to assess different irrigation strategies on tree growth and production components during three years in a young super high-density olive orchard (Arbequina cv.) located in northeast Spain. Four deficit irrigation strategies were compared to a control strategy based on replenishing crop evapotranspiration. The four strategies were as follows: Continuous Deficit Irrigation (CDI), two Regulated Deficit Irrigation strategies (Moderate, MRDI, and Severe, SRDI), and a precision Irrigation strategy based on daily trunk growth (Precision). In the Precision strategy, olive oil production increased by 7% and the vegetative variables did not show significant reductions, resulting in an average yearly water savings of 31% compared to the control strategy. The Regulated Deficit Irrigation strategies also produced promising results based on the high average yearly water-saving rates of 19% and 29%. However, the SRDI strategy exhibited significant reductions in tree height, lateral branches growth, olive yield, and oil yield compared to the control. On the other hand, the MRDI strategy did not differ significantly in oil yield, tree height, and lateral branches growth compared to the control or Precision strategies. Similarly, the CDI strategy resulted in significantly lower tree height, lateral branches growth, and production compared to the control. Although the observed reduced growth in both SRDI and CDI strategies presents an interesting opportunity for managing excessive vigor in super high-density olive orchards, it is important to consider that this approach may compromise production in successive seasons.