Impact of deficit irrigation with saline water on yield, soil salinization and water productivity of barley in arid regions of Tunisia
Field studies were conducted for two years to determine the effects of irrigation regimes with saline water (7.6 dS/m) on soil salinity, yield and water productivity of barley in the arid region of Tunisia. Barley was grown on a sandy soil and drip-irrigated with well water having an ECi of 7.6 dS/m. For two years, a complete randomized block design with three replicates was used to evaluate five irrigation regimes. Full treatment (FI) was irrigated with an amount equal to 100% of cumulated crop evapotranspiration (ETc), DI-50 treatment irrigated at the same frequency as FI treatment but with quantity equal to 50% of accumulated ETc during growing period and deficit irrigation during tillering stage (DI-Dev), maturity (DI-Mat) and both stages (DI-Dev+Mat). The results showed that soil salinity was significantly affected by irrigation treatments. Higher soil salinity was maintained in the root zone with DI-50treatment than full irrigation (FI). DI-Dev, DI-Dev+Mat and DI-Mattreatments resulted also in low ECe values. This highest soil salinity accompanied with DI-50 treatment reduced barley yield significantly. However, regulated deficit treatments provide acceptable yields compared to full irrigation treatment. Water productivity (WP) obtained in field experiments corresponds with values reported in the literature and was affected by irrigation treatments. The lowest WP values occurred under the FI treatment, while the highest values were obtained under DI-50 deficit irrigation treatment. However, the difference between FI, DI-Dev, DI-Mat and DI-Dev+Mat treatments was not significant. The full irrigation (FI) and deficit irrigation (DI-Dev, DI-Mat and DI-Dev+Mat) strategies were found to be a useful practice for scheduling barley irrigation with saline water under the arid Mediterranean conditions of southern Tunisia.