The Effect of Zinc and Salicylic Acid Application on Grain Yield, Essential Oil and Phytochemical Properties of Fennel Plants Under Drought Stress

To investigate the effect of different levels of drought stress, zinc and salicylic acid spray on yield and essential oil components of fennel, an experiment was conducted in two years 2018 and 2019 as split-plot factorial based on randomized complete block design with three replications at the research farm of Ivan city in Ilam province. The main factor consisted of irrigation regimes at three levels of non-stress, moderate stress and severe dehydration through irrigation levels of 50, 75 and 100 mm evaporation from Class A evaporation pan, respectively. The sub-factor consisted of nano fertilizer at two levels (without fertilizer and zinc nano-fertilizer spray) with salicylic acid spray at four levels (zero, two, four and six mmol). Drought stress decreased grain yield and essential oil yield. Fennel essential oil percentage increased with intensifying the drought stress. The concentration of 6 mM salicylic acid resulted in the highest essential oil percentage (2.8 %) and essential oil yield (29.2 kg/ha). Application of Zn nano-fertilizer at drought stress levels of 50, 75 and 100 mm increased the grain yield by 14 %, 2.5 % and 6.5 %, respectively. Most of the fennel essential oils consisted of Anethole, Fenicon, Estrogel and Limonene. The application of zinc nano-fertilizer increased the concentration of anethole and esrogel but decreased the concentration of fenecon and limonene. The application of salicylic acid also increased the amount of anethole and estrogel.