Periodic variation of the water use efficiency in durum wheat

Water Use Efficiency (WUF) of five durum wheat varieties (Khiar, Karim, Nasr, Razzak and Sobirano) cultivated in Tunisia was investigated. The experiment was conducted under rainfed field conditions, irrigated pots and test tubes at ESA Kef experiment station during the cropping season of 2010-2011. Under rainfed conditions, Khiar has the highest grain yield with 29.35 q ha(-1). Biological WUE ranged from 1.72-1.49 mg dry matter per g of water for Razzak and Nasr, respectively. The WUE of grain ranged.from 0.81-0.48 mg grain per g of water for Khiar and Sobirano, respectively. Biological WUE showed positive correlation to grain yield and stomatal density and negatively correlated with leaf area. Periodic water use efficiency in pot and test tube trials indicated variation of wheat genotypes according to stage periods and how the experiment was conducted. Test tubes trials showed high, accurate and maximum value of water use. Therefore, we can consider that Khiar has a high WUE in the first period; germination-early tillering (6.70 mg dry matter per g water). Nasr and Sobirano valorise well had got water use during the second period; tillering (9.16 and 10.20 mg dry matter per g of water). Razzak shows a high WUE for the third period; booting-early heading (9.06 mg dry matter per g of water). Finally, Karim cultivar has the highest WUE during for the fourth period; heading-physiological maturity (22.13 mg dry matter per g of water). Periods of high WUE can be targeted for appropriate time of wheat cultivar irrigation.