Assessment of yield and water use efficiency of durum wheat as affected by irrigation practices and soil properties in the irrigated area of oued rmel in Tunisia

This work aims to study the impact of total available soil water in the root zone (TAW) on the relation between irrigation regime and water use efficiency of a durum wheat (Triticum durum Desf. Var. Karim.) cultivar in the pedoclimatic conditions of the irrigated area of Oued Rmel in Tunisia. After calibration, STICS model was used to simulate effects of two irrigation scenarios on water use efficiency of durum wheat over a 20-year period with regard to farmers irrigation practices in the study area. To carry out the study, three types of soil in the Oued rmel irrigation scheme were chosen on the basis of their TAW. Two scenarios of irrigation scheduling were designed through the STICS model: (i) irrigation was scheduled when 50% of the TAW was depleted (I50); (ii) irrigation was scheduled when 25% of the TAW was depleted (I25). Results showed that lowest values of grain yield were obtained in soil having low TAW as a consequence of a frequent water stress occurring during the reproductive stage of wheat. The highest values of WUE, as determined at grain and biomass basis (WUEg and WUEbio indexes), were obtained when irrigation was scheduled at 25% of the TAW depletion. In I50 and I25 scenarios, highest WUEg, averaging respectively 2.25 and 2.23 kg m -3 was