Effect of Soil Type on Grapefruit and Shaddock Essential Oils

Grapefruit and shaddock essential oils (EOs) have remarkable biological activities. Soil types are characterized by various properties which affect the essential oils of grapefruit and shaddock. Many Citrus species are cultivated in the Nile Valley of Egypt, which is characterized by its clay soil, but there are no large areas cultivated with both grapefruit and shaddock. The reclaimed desert in Egypt which characterized by sand soil is expanded by planting many Citrus species, which produce different residues such as leaves, flowers, and peels rich in essential oil, which is used in the production of natural raw materials as a source for medicine and food. Thus, the variations of grapefruit and shaddock essential oils and their constituents were evaluated under sand and clay soils to find out the extent of the opportunities for expanding their cultivation in the new reclamation region as a natural source of EO. The leaves, flower, and peel EOs of grapefruit and shaddock were isolated by hydro-distillation and analyzed by gas chromatography and gas chromatography/mass spectrometry; data were statistically analyzed by one-way analysis of variance. Samples collected from trees grown in sand soil produced the greatest amounts of essential oil in both species whatever the organ from which this oil was extracted. Limonene was of the major compound in both peel and flower grapefruit essential oils, while sabinene was the predominant one in leaves EO (39.8% and 44.8%, in clay and sand soils respectively). E- phytol, linalool, and limonene were the predominant constituent in leaves, flower, and peel of shaddock essential oil, respectively. Various identified constituents in leaves, flowers, and peels noteworthy the presence of oxygenated diterpenes in percentage not less than 33% in leaves shaddock essential oil which was completely omitted in the other organs and in the grapefruit EOs. The monoterpene hydrocarbon was the major chemical class in various essential oils of grapefruit; oxygenated diterpenes, oxygenated monoterpenes, and monoterpene hydrocarbon were the main chemical classes of leaves, flower, and peel essential oils from shaddock, respectively. In the essential oil contents (%), most of the main constituents and major chemical groups were higher under sand soil than clay soil. This study serves as a reference for selection the suitable soil to produce the essential oil according to the components of interest; also, this trial recommends the cultivati