EFFECT OF IRRIGATION WATER REDUCTION STRATEGIES ON QUALITY AT HARVEST AND DURING STORAGE OF IN-SHELL ALMONDS

Almond trees (Prunus amygdalus L. ‘Marta’) were subjected to 4 irrigation treatments: I) full irrigation at 110% of ETc (FI) II) partial rootzone drying at 50% of ETc, periodically supplied to only one side of the root system, (PRD); III) regulated deficit irrigation at 100% of ETc until June and at 30% of ETc from June until harvest (RDI); IV) rain fed (NI). In August 2007, almonds were harvested, hulled, dried and stored in shell at room temperature for 9 months. Yield average (per ha) was recorded. At harvest, kernel and nut dimensions and weight were determined. Initially and after 2, 5 and 9 months of storage peel color, rupture force, sensorial analysis and oil content (on the kernels), acidity, peroxide value and tocopherols content (on the oil), and antioxidant activity, total phenols and sugar composition (on the defatted powder) were carried out. Yield resulted significantly lower for NI trees than for FI trees, while RDI and PRD trees showed intermediate values. NI kernels and nuts had the lowest weight and size. NI kernels showed a different peel color from the other treatments, while rupture force decreased during storage regardless of irrigation. NI kernels had higher total sugar and sucrose content, with no difference among other treatments. FI, PRD and RDI samples did not show difference in antioxidant activity during storage, while NI showed a statistically lower value than PRD, the highest decrease rate in phenols content, and also received the lowest sensorial evaluation for appearance. Oil acidity and peroxide values increased during storage, regardless of irrigation. Oil from NI samples had higher α-tocopherol content than RDI and FI, after 5 months of storage. In conclusion, PRD and RDI did not significantly affect the yield and produced almonds similar in quality to those obtained by FI, reducing the use of water.