Evapotranspiration and components of corn (Zea mays L.) under micro irrigation systems in a semi-arid environment

Aim of study: This work summarizes the influence of surface drip irrigation (DI) and subsurface drip irrigation (SDI) systems on corn growth indices and actual evapotranspiration (ETc-act) and its components of plant transpiration (T-p) and soil evaporation (E). Area of study: Karaj, Iran Material and methods: The experimental soil was loamy. The corn ETc-act of each mini-lysimeter was measured based on the water balance method. The E was measured using two mini-lysimeters and T-p was estimated from the difference between ETc-act and E. Main results: The resulting data showed that the ETc-act was lower under SDI (384.8 mm) than under DI (423.4 mm). The K-cb-(m) for the corn increased after sowing and peaked during the mid-season stage, with an average value of 0.47, a minimum value of 0.0 and maximum value of 1.52 under DI and 0.53, 0.0 and 1.74 respectively, under SDI. For Ke-m, the average, minimum and maximum values were 0.33, 0.20 and 0.58 under DI and 0.23, 0.15 and 0.46 respectively, under SDI. The biomass yield was much higher under SDI (81.90 ton/ha) than under DI (63.21 ton/ha). Less E and more T-p occurred under SDI than under DI. SDI achived superior WUE (8.32 kg/m(3)) compared with DI. Research highlights: SDI was superior to DI based on biomass yield, corn height, stem diameter, and leaf area index which contributed to more favorable soil moisture conditions and low weed incidence; Thus, the SDI system is more productive and would better increase WUE than the DI system.