Biomass yield potential of Tulsi (Ocimum sanctum L.) in European conditions

Ocimum sanctum L., commonly known as holy basil, tulsi or tulasi, is a medicinal plant that offers many industrial uses in medicine, cosmetics and the food industry. Recently, the interest has risen in good-quality biomass from this plant. Therefore, the objective of this study was to determine an optimum density of O. sanctum vegetation when grown in Central Europe in order to achieve the highest possible yield of the above-ground biomass. The following were assessed as criteria of quality of the obtained biomass: the content and composition of the essential oil for O. sanctum vegetation with the highest yield, and the content of rosmarinic acid as an important representative of polyphenolic compounds providing a high industrial potential. The yield characteristics were studied in two localities and in two years for three spacing values, from the most dense (10 x 15 cm) to an intermediate (15 x25 cm) and sparse (20 x 35 cm) spacing. It was found that two good-quality harvests could be obtained in the temperate zone (the first one at the end of June and the second one in the middle of August). As we found out, a dense spacing of 10 x 15 cm provides a significantly higher yield compared to spacings of 15 x 25 cm or 20 x 35 cm, i.e. the average yield was 1.67 kg.m(-2) of fresh biomass for the first harvest and 3.72 kg.m(-2) of fresh biomass for the second harvest. The dense spacing can thus be expected to provide a potential annual average yield of 54,057 kg.ha(-1) of fresh biomass or 5963 kg.ha(-1) of dry biomass. As for the dense spacing, the harvested biomass was also of good quality. It contained about 1% essential oil with a major proportion of linalool (34-39%) and estragole (22-26%), as well as rosmarinic acid, whose average content ranged from 1.05 mg.g(-1) to 6.34 mg.g(-1). Therefore, a dense spacing of 10 x 15 cm can be recommended for O. sanctum growing in the temperate zone.