Saline reclaimed water affected leaf nutritional and chlorophyll traits in almond trees

The evaluation of non-conventional water resources such as reclaimed water and water-saving techniques has gained importance during the last decades in arid and semiarid countries. This one-year study assessed the effects of two irrigation water sources: DW, desalinated water obtained by treating wastewater coming from Bari secondary wastewater treatment plant by using DESERT technology (DEsalination and SEnsoR Technology) till reaching an ECw of 1.2 dS m(-1), and saline RW, obtained by mixing the secondary wastewater with the brine produced on the DESERT prototype till reaching an ECw of 3 dS m(-1). Two irrigation strategies were used for each water source: control full irrigation, FI, 130% of crop evapotranspiration (ETc) and regulated deficit irrigation, RDI, at 80% of ETc during the kernel-filling period, in a non-bearing almond crop (Amygdalus communis L. 'Tuono' grafted on a hybrid Rootpak 20 (R) of Prunus besseyi x Prunus cerasifera L-H. Bailey and Ehrh.). Trees were planted in 100 L pots filled with representative loam soil of the area (Apulia Region, Italy). Our results showed that a high concentration of leaf phytotoxic elements (Na+ and Cl-) from RW caused a significant reduction in the K/Na ratio and total leaf chlorophyll, classifying the Rootspack 20 (R) as sensitive to salinity due mainly to Na ion uptake. These results highlight that, in semiarid areas, RW and RDI strategies should be cautiously used in future irrigation of almond. Long-term studies are needed to establish suitable management practices under salinity conditions.