This study was designed to evaluate the yield response of trickle-irrigated corn grown on a clay-textured soil under the and Southeast Anatolia Project (GAP) area conditions during the 2000 growing season at Koruklu in Turkey. The effects of three different irrigation levels (100, 67 and 33% of cumulative Class-A pan evaporation on a three- and six-day basis), and two irrigation intervals (three- and six-day) on yield were investigated. Trickle laterals were laid out on the soil surface at a spacing of 1.40 m. A total of 581 mm of water was applied to the full-irrigation treatments (100%) for both irrigation intervals. Seasonal water use ranged from 358 to 562 mm across treatments. Highest average corn yield (11920 kg ha(-1)) was obtained from the full-irrigation treatment (100%) with six-day interval. Corn grain yields varied from 7940 to 11330 kg ha(-1) and 7253 to 11920 kg ha(-1) for three- and six-day irrigation intervals, respectively. Irrigation levels significantly increased yield. Maximum irrigation water use efficiency (IWUE) and water use efficiency (WUE) were 2.53 and 2.27 kg m(-3) in treatment of I-33 with six-day interval. Both IWUE and WUE values varied with irrigation quantity and frequency. The research results revealed that the trickle irrigation system could be used successfully for irrigating corn crops under the and climatic conditions of the Southeast Anatolia Project (GAP) area in Turkey. Copyright (C) 2002 John Wiley Sons, Ltd.