Journal of Crop Production and Processing

This research was designed and implemented to determine the effect of different irrigation regimes on the grain yield, dry matter, tiller number per unit area, degree of maturity, panicle harvest index, percentage of leaf rolling, day to 50% flowering, and the physiological maturity of rice genotypes, using a split plot randomized complete block design in two years (2014 and 2015). Four irrigation regimes (every 1, 3, 5 and 7 days of irrigation) were assigned to the main plots and 12 rice genotypes were in the subplots with three replications. The results showed that irrigation regimes, genotypes and interactive effects of these two factors had a significant impact on all measured traits at the 1% probability level. All genotypes tended to produce the most grain yield in the second irrigation regime (the three-day irrigation interval); genotype IR 81025-B-327-3, with 6555.10 kg ha^-1 of grain yield, out-performed the remaining genotypes in this level of irrigation regime. Also, the second irrigation regime (the three-day irrigation interval) had the highest amount of dry matter, tiller number, degree of maturity, and panicle harvest index. Considering the positive and significant correlation between these traits and grain yield, their increase could be regarded as one of major reasons for the increase in the grain yield at the second irrigation regime (the three-day irrigation interval). The degree of maturity with day to 50% flowering and physiological maturity were decreased with increasing irrigation intervals; the latter modifications could be regarded as a defense mechanism to avoid drought