The effect of irrigation and nitrogen fertilizer on yield, inputs use efficiency and seed quality of sesame cultivars

In order to investigate the quantitative and qualitative response of three sesame cultivars (Sesamum indicum L.) to different irrigation and fertilizer treatments, an experiment was conducted in the research farm of Karaj Seed and Plant Breeding Institute during 2016 and 2017. The experiment was performed as split-factorial plots in a randomized complete block design with three replications. Irrigation treatments at two levels including low irrigation regime (irrigation after 80% of usable soil moisture) and full irrigation (irrigation after 40% of usable soil moisture) in main and factorial plots with different amounts of nitrogen (0, 60 and 120 kg N ha-1) and sesame cultivars (Oltan, Dashtestan 2 and Naz single-branched) were placed in subplots. The results showed that in full irrigation conditions, application of 120 kg N ha-1 increased sesame seed yield by 83% compared to non-application. In contrast, this increase in yield in response to the application of nitrogen in low irrigation treatment was 40%. In general, the results showed that in full irrigation treatment, the use of nitrogen fertilizer for all three cultivars can be justified. Maximum grain yield was obtained in Oltan (1106 kg ha-1), Dashtestan 2 (1012 kg ha-1) and Naz single-branched (634 kg ha-1) cultivars with 115, 117 and 100 kg N ha-1, respectively. In contrast, in conditions of low irrigation, in none of the cultivars, grain yield higher than 500 kg N ha-1 was not achieved even with high amounts of nitrogen (60 and 120 kg N ha-1).