Volatile Oil Yield and its Components of Menthol and Limonene of Peppermint Affected by Foliar Spray and Lighting Intensity

Abstract

A field experiment was conducted at a research station in the College of Agricultural Engineering Sciences, University of Baghdad, in spring 2021 to study the effects of foliar spraying of yeast extract, urea, and nano-amino acids and two lighting intensities on volatile oil yield and its components, menthol and limonene. The experiment had two factors: ambient type and lighting. The second component was foliar spraying yeast extract at 5 and 7.5 g.L-1, urea at 1000 and 2000 mg.L-1, and nano amino acids at 1 and 1.5 ml.L-1. P, K, and half of nitrogen were supplied to the soil. Randomized Complete Block Design (RCBD) with three replicates was used for the experiment. Plants grown at 100% lighting intensity had the highest percentage and production of aromatic oil, menthol, and limonene (2.24, 45.49, and 3.30%; 20.20, 9.49, and 0.74 kg.ha-1, respectively) compared to 50% lighting intensity (1.77, 31.00, and 1.91%; 11.64, 3.62, 0.24 kg.ha-1). The two treatments of spraying urea (2000mgN.L-1) and nano amino acids (1.5ml.L-1) at 100% lighting intensity yielded the highest percentage and yield of aromatic oil, menthol, and limonene at 3.07, 45.78, 3.99%; 50.23, 4.60%; 32.74, 16.44, 1.50 kg.ha-1, 29.37, 14.32, 1.17 kg.ha-1, respectively.