Partial Rootzone Drying As a Water Conservation Strategy for Tropical Citrus Production

Partial rootzone drying (PRD) is an irrigation strategy that consists in keeping half of the rootzone well-irrigated while the other half is allowed to dry in order to trigger root-to-shoot signaling to increase water use efficiency. A field experiment was conducted to evaluate the effect of PRD on growth and fruit production in mature grapefruit (Citrus paradisi Macf.) trees. Three different irrigation treatments were applied to 22-year-old ‘Rio Red’ grapefruit trees grown in a one acre plot: 1) Control: both sides of the rootzone were irrigated with drip irrigation (double line); 2) PRD: one part of the rootzone was irrigated with a single drip line; and 3) MS: microsprinklers. After the first year, PRD saved 41% water compared to the control without affecting fruit quality; no differences were found in fruit diameter, fruit firmness, juice percentage, total soluble solids, acidity , maturity index or yield. PRD did not cause any negative effect on tree overall condition during the first year. Second and third year still need to be evaluated but if data follow the same trend, this could be suggested as an effective water conservation approach.