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® of Prunus besseyi × 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® 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.