|Ebelhar, M. Wayne|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2009
Publication Date: 1/11/2010
Citation: Zheljazkov, V.D., Cantrell, C.L., Astatkie, T., Ebelhar, M. 2010. Productivity, Oil Content and Composition of Two Spearmint Species in Mississippi. Agronomy Journal. 102(1):129-133. Interpretive Summary: 'Scotch’ (Mentha x gracilis Sole) and ‘Native’ (Mentha spicata L.) spearmints are well established crops in the northern part of the United States, but have not been evaluated in the southeast. Recently, there has been an expanding market for spearmint essential oils and the essential oil broker companies are interested in expanding the spearmint production area into the southeastern United States. Two-year field studies were conducted at two locations in Mississippi (Verona and Stoneville) to evaluate the effect of nitrogen (N) application rate and cut (harvest time) on ‘Scotch’ and ‘Native’ spearmint herbage yield, essential oil content, oil composition, and the yield of individual oil constituents. In summary, ‘Scotch’ and ‘Native’ spearmints can be successfully grown in Mississippi and presumably in other regions in the southeastern US with similar environmental conditions. Overall, location, N application rate, and cut would affect ‘Scotch’ and ‘Native’ spearmints productivity, oil content, and composition. Increased N application rates at 80 and then at 160 kg ha-1 may increase herbage and oil yields from ‘Scotch’ spearmint, suggesting that commercial ‘Scotch’ spearmint plantation should be provided with 160 kg N ha-1(fertilized with 80 kg ha-1 for each cut). ‘Native’ spearmint could provide similar yields when fertilized with either 80 or 160 kg N ha, but the higher N rate would increase oil yields. Also, yields from the first cut of ‘Native’ spearmint were greater than yields from the second cut, however, the oil content from the second cut was higher than in the herbage from the first cut.
Technical Abstract: 'Scotch’ (Mentha x gracilis Sole) and ‘Native’ (Mentha spicata L.) spearmints are grown in the northern United States, but have not been evaluated in the Southeast. Two-year field studies were conducted in Mississippi at two locations (Verona and Stoneville) to evaluate the effects of N application rate and cut (harvest time) on yields, essential oil contents, compositions and the yield of individual oil constituents [(-)-carvone, (R)-(+)-limonene and eucalyptol] in Scotch and Native spearmints. Application of N at 80 and 160 kg/ha increased herbage and oil yields in Scotch, suggesting that commercial Scotch plantations should be provided with 160 kg N/ha. Native spearmint provided similar herbage yields when fertilized with 80 or 160 kg N/ha, but the higher N rate increased oil lyields. The essential oil yields in this study were higher than the average oil yields for spearmint grown in the United States during 2008. The essential oil composition of Scotch and Native spearmints grown in Mississippi were simlar to the oil produces in other states and other regions in the world. At the Verona site, the average (-)-carvone concentration in the essential oil of Scotch was 68 to 75%, whereas the concentration of (-)-carvone in Native oil ranged from 59 to 62%. At Stoneville, the average (-)-carvone concentration in Scotch oil was 74%, whereas (-)-carvone in Native oil was 68 to 74%. Both Scotch and Native spearmints could be grown as essential oil crops in Mississippi and possibly in other areas of the southeastern United States.