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The present study was conducted to investigate the effect of different levels of irrigation and withholding irrigation on yield and yield components of cornhybrid S.C.704 in 2009 in Ahvaz Shahid Salemi Experimental Field.The experiment was set up as a factorial in a randomized complete block design with three replications. Treatments were arranged with three irrigation levels:I1,I2 and I3 in which each was irrigated equivalent to 100%(control),80% and 60% available water into targeted soil respectively .Using pan evaporation of class A to calculate the quantity of water in regard to evaporation for each treated plot,and three levels of withholding water:S1,S2 and S3 which following with no implement of water stress (control), withholding water at the stage of 8th leaf growth and withholding water at the silk stage, respectively. The results of data analysis indicated that there was significant effect on kernel and dry matter yield due to irrigation and non-irrigation treatments. As drought stress severity was promoted kernel, dry matter yield, harvest index and biological yield were significantly decreased. Severe drought stress (I3) caused reducing the kernel yield by 59% when compared to plants grown under control (I1) condition. Withholding water during silk stage drastically reduced corn yield in comparison with withholding water at the stage of 8th leaf growth and control treatments.Reduction in number of seed row in cob, number of seeds per row and 1000–grain weight were primary factors for corn yield and yield declining.