Co-Authors:
Fischer, R., Division of Medicinal and Aromatic Plants, Agriculture Research Organization, Newe Yaa'r Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel
Nitzan, N., Division of Medicinal and Aromatic Plants, Agriculture Research Organization, Newe Yaa'r Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel
Chaimovitsh, D., Division of Medicinal and Aromatic Plants, Agriculture Research Organization, Newe Yaa'r Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel
Rubin, B., Faculty of Agriculture and Food Quality, Hebrew University, P.O. Box 12, Rehovot, 76100, Israel
Dudai, N., Division of Medicinal and Aromatic Plants, Agriculture Research Organization, Newe Yaa'r Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel
Abstract:
The aroma in sweet basil is a factor affecting the commercial value of the crop. In previous studies leaf age was considered to be a factor that influences the composition of essential oil (EO). In this study it was hypothesized that a single observation of the EO content in leaves from different positions on the main stem (young vs old) could predict the developmental changes in the plant during its life cycle. Plants harvested at week 16 demonstrated an exponential increase (R2 = 0.92) in EO concentration in leaves on the main stem and lateral shoots, indicating higher EO concentrations in younger than in older leaves. Eugenol and methyleugenol predominated (28-77%) in the extract. Eugenol levels were higher in younger leaves (∼53%), and methyléugenol levels predominated in older leaves (∼68%). Linalool was lower in mature leaves than in younger leaves. This suggested that eugenol converted into methyleugenol and linalool decreased as leaf mature. However, in weekly monitored plants, the levels of these compounds in the EO had limited variation in the maturing leaf regardless of its position on the stem. This proposed that the EO composition in an individual leaf is mostly affected by the leaf position on the stem and not by its maturation process. Because leaf position is related to plant development, it is probable that the plant's physiological age at the time of leaf formation from the primordial tissue is the factor affecting the EO composition. It was concluded that interpretation of scientific observations should be carried out with caution and that hypotheses should be tested utilizing multifaceted approaches. © 2011 American Chemical Society.