Deficit Irrigation Treatments in Citrus X Limon in Mediterranean Area: Physiological and Financial Evaluation

Mediterranean citrus production faces increasing water scarcity and rising irrigation costs under climate change, making the identification of agronomically and economically sustainable irrigation strategies essential. Although deficit irrigation (DI) has been widely studied in citrus, most research has primarily focused on physiological responses or yield, while integrated evaluations combining crop performance with farm-level profitability under real commercial conditions remain limited. An experiment tested three treatments on plots with ten lemon trees (Citrus x limon) each: Moderate deficit irrigation (DI1) with fertigation at 3.5 l/h (87% ETc), severe deficit irrigation (DI2) at 2.7 l/h (67% ETc), and a control irrigation (CI) at 4 l/h (100% ETc). All treatments included six irrigation emitters per tree. Black plastic mulch was used, and data were collected over eight months on growth, photosynthetic parameters, mineral nutrition, and financial performance. DI1 may be suitable during years with average or high rainfall but is not recommended in summer or droughts while DI2 is only useful for short-term survival under extreme drought conditions. DI1 showed similar vegetative growth, photosynthetic parameters, and mineral levels as the CI, though with lower yields. DI2 significantly underperformed in all parameters. Financially, CI was most profitable, followed by DI1, while DI2 had the lowest return. Then, DI methods can reduce water use by 10–33%, albeit with an 8% (DI1) to 62% (DI2) drop in profitability. DI1 treatment can be a practical option under favorable weather, offering a balance between water savings and economic returns. In contrast, DI2 treatment is not sustainable for ongoing productivity.