effects of irrigation and nitrogen application rates on yield and yield components of corn, sesame and sugar beet in mashhad climatic condition

in many crops, incorrect management of nitrogen and water is one of the most important factors in the resources productivity such as water and nitrogen. in order to evaluate the effects of different nitrogen levels (zero, 50, 100 and 150 kg ha-1) and irrigation application rates (100, 75 and 50% of water requirement per species) on corn, sesame and sugar beet, three separate experiments was conducted in agricultural research station of ferdowsi university of mashhad, iran, in 2009-2010 growing season. three separate experiments were arranged by strip plots in randomized complete block design, with three replications. the results showed that effect of irrigation application rates on biological yield and grain number per ear and interaction effects of water × nitrogen on plant height, 100 grain weight and grain yield of corn was significant. with decreasing irrigation over 25 % water requirements, the highest grain yield (4.93 ton ha-1) in corn observed by applying nitrogen equal to 50 kg.ha-1. in addition, the highest maize yield (9.41 ton.ha-1) in mentioned was obtained by supplying 100 % water requirements. effects of irrigation levels on plant height and the interaction effects of water × nitrogen on 1000 grain weight in sesame was significant. under no water stress, the highest grain yield (1.22 ton ha-1) in sesame was obtained with applying 50kg nitrogen per ha. with supplying 75% water requirements plus 50 kg nitrogen per hactar, maximum yield of sesame (820 kg ha-1) was obtained. results of this study indicated that interaction between studied factors had insignificant effect on economic and biological yield in sugar beet. with supplying 25% water requirements plus 50 kg nitrogen per ha, maximum yield of sugar beet (58.37 ton ha-1) was achieved. it seems that suitable nitrogen management can be considered as approach in optimize the water consuming.