Improvement of fruit quality by moderate water deficit in three plum cultivars (Prunus salicina L.) cultivated in a semi-arid region

Introduction. Drought can affect the qualitative and nutritional attributes of plum (Prunus salicina L.). The aim of this work was to study the effect of regulated deficit irrigation (RDI) on the quality of plum fruits. Materials and methods. Experiments were conducted during two consecutive seasons (2011-2012) with three cultivars ('Black Diamond', 'Black Gold' and 'Black Star') recently introduced in the region of Regueb (center of Tunisia) characterized by a semi-arid climate. During the fruit growth period, treated trees (RDI 50) received 50% of the irrigation water provided to the control (CI) for three months. Results and discussion. Water restriction reduced the diameter and weight of the fruit though the extent depended on the cultivar. However, other measures of fruit quality were improved for all cultivars with an increase of fruit firmness, pH, soluble solids and sucrose content, and a decrease of total acidity. Additionally, 'Black Diamond' fruit from treated trees had high level of total phenolics and flavonoids. Conclusion. Regulated deficit irrigation may save water in semi-arid regions and improve fruit quality with only moderate impact on productivity.