The Effect of Using Nitrogen and Potassium Fertilizers and Irrigation Regimes on Grain Yield Related traits of Sesame (Sesamum indicum L.)

In order to study the grain yield attributes of sesame in the presence of nutritional treatments and different irrigation regimes, a factorial split-plot experiment was conducted based on randomized complete block design with three replications in Shahed University of Tehran, Iran during 2015-2016. The treatments included irrigation regimes (full irrigation and irrigation up to 65 and 75 BBCH scales), three types of nitrogen fertilizers (nitroxin, urea, and the combination of nitroxin and 50% urea) and four levels of potassium fertilizer (non-fertilized as control, spraying and soil application of potassium nano-chelate and potassium dioxide). The triple interaction effect of irrigation × nitrogen × potassium was significant on plant height, the number of lateral branches, capsules, seeds per capsule, and grain yield. The highest grain yield was obtained from plants irrigated up to 50% of seed ripening (75 BBCH) in the absence of application of potassium and use of nitroxin with an average of 1340.5 kg ha-1 leading to 35% increase, compared to the control treatment. In addition, the grain yield was positively and significantly correlated with stem diameter, plant dry weight, number of capsules and seeds per capsule, and 1000-seed weight. A weak correlation was observed among the morphological traits. Further, there was no significant correlation between morphological and yield attributes. Based on the results of stepwise regression, the maximum grain yield difference was related to the total number of capsules, 1000-seed weight, and number of seeds per capsule, together explaining 98.8% of the grain yield changes.