|EBELHAR, M. WAYNE|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2008
Publication Date: 8/1/2008
Citation: Zheljazkov, V.D., Cantrell, C.L., Ebelhar, M., Rowe, D., Coker, C. 2008. Productivity, Oil Content, and Oil Composition of Sweet Basil as a Function of Nitrogen and Sulfur Fertilization. HortScience. 43(5):1415-1422.
Interpretive Summary: Sweet basil (Ocimum basilicum L.) is the most widely grown species of the genus Ocimum L. Recent research demonstrated that sweet basil could be a feasible essential oil crop for Mississippi and possibly the southeastern U.S.; however, basil plant nutrition has not been investigated in the southeastern U.S. Prior research in other parts of the world demonstrated significant effect of plant nutrition on sweet basil productivity and oil composition. Nitrogen is the major modifier of crop yields (Marschner, 1999). Previous research on sweet basil nutrition has demonstrated a positive effect of increasing N rates on basil productivity. The hypothesis to be evaluated in this study was that N and S rates would have a significant effect on sweet basil productivity and oil content, and would significantly impact the concentration and yield of (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol. Furthermore, N and S fertilization of sweet basil could be used as a tool to target the production of basil with increased essential oil yields or oil with a desirable composition (an elevated concentration of a compound of interest). The objective of this study was to evaluate the effects of N and S application rates on total basil production, oil content, dry herbage yield, essential oil composition, and yield of major oil constituents. The research has focused on the quantification of (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol, because these are the major important basil oil constituents and previous research indicated that these constituents were relatively conservative (stable) traits. Herewith, the actual (real) concentrations of the four major constituents in basil oil, as a function of N and S fertilization are reported. The results from this study demonstrated that N and S applications can be used as management tools with respect to sweet basil production, oil content, and oil composition.
Technical Abstract: Nitrogen (N) and sulfur (S) were believed to be important nutrient management tools for the production of sweet basil (Ocimum basilicum L. 'German') with desirable oil content and composition and also acceptable herbage yields. A multi-location research study was initiated to evaluate the effect of N (0, 60, 120, and 180 kg N ha-1) and S (0, 20, 40, and 80 kg S ha-1) rates on biomass production, oil content, and oil composition for sweet basil. The three locations in Mississippi (Stoneville, Poplarville, and Verona) were selected based on geographic and climatic variation. Location, N rate, and their interaction were significant on basil dry herbage yields. The herbage yield means were 4,967 kg-1 ha-1, 2,907 kg-1 ha-1, and 2,122 kg-1 ha-1 for Poplarville, Verona, and Stoneville, respectively. Oil content was significantly affected by location with means of 0.69%, 0.80%, and 0.64% for Stoneville, Poplarville, and Verona, respectively. Location, N, and S had significant effects on oil yields, with means of 14.7, 38.7, and 18.5 kg-1 ha-1, for Stoneville, Poplarville, and Verona, respectively. Overall, essential oil yields were maximized at N application rates of approximately 50 to 60 kg N ha-1, whereas maximum response to S fertilization appeared to be beyond 80 kg S ha-1. Location and N application rates had significant effect on the yields (per area basis) of the major basil oil constituents (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol, whereas S had a significant effect on eucalyptol yield only. Eucalyptol concentration was positively correlated to the concentration of (–)-bornyl acetate. This is the first study to quantify (in real concentration) the response of the major sweet basil oil constituents (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol as a function of N and S application rates. Also, it is the first study to demonstrate a strong response of basil oil yield to S. The results from this study demonstrated that N and S applications can be used as management tools with respect to sweet basil production, oil content, and oil composition.