Effect of organic agriculture practices on the volatile aroma components of some essential oil plants growing in Egypt II: sweet Marjoram (Origanum marjorana L.) essential oil

Abstract

AbstractSweet marjoram (German type) was grown in Egypt under the conditions of organic and traditional agriculture. Mature compost was used as an organic fertilizer, while ammonium sulphate was used as a chemical fertilizer. Two levels of each fertilizer were used during plant growth. The crops were harvested and hydrodistilled in June and September, the isolated essential oil was fractionated into oxygenated and hydrocarbon fractions, then each fraction was analysed by GC and GC–MS. The results showed that the fresh herb of marjoram plants positively responded to increased levels of either organic or chemical fertilizers. The herb yield was the highest in the September harvest. Although the higher level of organic fertilization negatively affected the oil content in the fresh herb, however, the total oil yield per plant remained comparable with the lower levels of both organic or chemical fertilization. Regarding the oil composition, the results showed that marjoram (German type) grown in Egypt belongs to the cis‐sabinene hydrate/terpinene‐4‐ol chemotype. The chemical composition of marjoram essential oil did not change due to the fertilization type or level, but rather the relative percentage of certain constituents were affected. The highest concentration of cis‐sabinene hydrate (24.1%), under organic treatment was reported for a June crop fertilized at level I, while the highest concentration of terpinene‐4‐ol, (39.5%), under the same treatment, was detected in a June crop at level II fertilization. Other components showed different concentrations depending on season of harvesting, treatment, and level of fertilization. Copyright © 2003 John Wiley & Sons, Ltd.