Combined Effects of Irrigation Interval and Composition of Macronutrients on Changes in Essential Oil and Chemical Compounds of Ginger (Zingiber officinale R.)

To evaluate the changes in essential oil and chemical compounds of ginger plant under the influence of irrigation interval and NPK macronutrients, an experiment was carried out using randomized complete blocks in the form of a split plot with 9 treatments and 3 replications in Pakdasht Region, in 2021. Treatments included irrigation internals at three levels: V1=4, V2=6, and V3=8 days, as the main factor, and NPK at three levels, F1= (N: 300, P: 100, K: 200), F2= (350, 150, 250), F3 :( 250, 50, 150) (kg.ha-1) as the sub-factor. Extraction of essential oil in this research was done by distillation with water using a Cloninger machine, and the analysis of essential oil compounds was done by gas chromatograph, and 34 chemical compounds were identified. The main components of essential oil in terms of percentage included (α-zingiberene=23.65), (geranial=11.09), (camphene=9.58), (β-sesquiphellandrene =8.43), (β-bisabolene=3.75) and (α-curcumene=2.6). These 6 compounds included 59.1% of the total ginger essential oil, and the other 28 compounds made up only 40.9% of the total essential oil. The results of analysis of variance showed that the interaction effect of irrigation and studied fertilizers on essential oil and main compounds of ginger essential oil were significant at the 1% probability level. The best treatments for essential oil and camphene traits were V1F3, geranial V3F2, α-zingiberene V1F2, and for three traits of α-curcumene, β-bisabolene, and β-sesquiphellandrene was V3F3. Some of the compounds in ginger essential oil were increased by optimal irrigation and supply of essential nutrients for the plant, but some compounds increased under water stress and insufficiency of NPK.