A field experiment was conducted in Al-Yusufiya district - Al-Mahmoudiya district, Baghdad province during the winter season 2021, to study improving the efficiency and management of water use and the productivity of lettuce under different irrigation systems. The Nested-Factorial Experiments design was used, where the main plots include the first factor, irrigation levels (I1) 50%, (I2) 75%, (I3) 100, (I4) 125%, (I5) 150% ETpan. After depleting 35% of the available water and in terms of climatic data from the American Evaporative Basin, Class A. Then the main factor is divided into three replicates, and the coefficients of the second factor are distributed randomly within each replicate, which includes the irrigation system: surface drip irrigation, a plant line drip line (S1) and a two plant line drip line (S2), The subsurface drip irrigation system is a plant-line drip line (SS1) and a two plant drip line (SS2) and furrows irrigation system (SI.) The results show that the highest field water use efficiency is 108.2 and 104.1 kg m> for the subsurface drip irrigation system (SS2) and (SS1) and at irrigation level I2. While the field water use efficiency of the surface drip irrigation system was 72.07 kg m-3 at the level of irrigation I3 for treatment (S1) and for treatment (S2) it reached 68.90 kg m-3 at the level of irrigation I4. As for irrigation in-furrow (SI), it reached 33.30 kg m for irrigation level I2 and the highest yield was 286.2 Mg. ha-1 for I5SS2 treatment, and the lowest yield was 62.50 Mg. ha-1 for I1S1 treatment. The highest average head length and head circumference were 46.19 and 69.20 cm at I5SS1 treatment, respectively.
