The present work analyzes the effects of different water application levels on agronomic parameters and water use efficiency of a durum wheat (Triticum durum Desf. Var. Karim.) cultivar under the Mediterranean climatic conditions in central Tunisia. The objective of this work was to identify an appropriate irrigation strategy associated with high crop water use efficiency. Field experiment was conducted at the Higher Institute of Agronomy of Chott Meriem during the growing season 2011-2012. The irrigation strategy consisted in maintaining fixed the irrigation intervals and changing the volumes of water applied as a percentage of the crop water requirements. The effects of three irrigation treatments were investigated. The irrigation treatments were full irrigation (T1) corresponding to 100% of predetermined irrigation water levels, (T2) 75% of full irrigation and (T3) 50% of full irrigation. Results concerning water use efficiency revealed that T1 and T3, with respectively 1.72 and 1.6 kg/m3, were classified in the same group. T2, with 1.43 kg/m3, resulted in lowest water use efficiency. Comparing the effects of water supply on yield components, the best results were registered for T1 while the lowest yield components were obtained for T3. LAI from T1 was significantly higher than in the other treatments. According to the study results, each increase in irrigation regime increased days to maturity. The results achieved in this study showed that irrigating winter wheat with continuously providing only 50% of the crop water requirements in semi arid climate in Tunisia could result in high efficient irrigation water use.
