Growth characters and chemical constituents of Dracocephalum moldavica L. plants in relation to compost fertilizer and planting distance

Two experiments were carried out during two successive seasons to investigate the response of Dracocephalum moldavica L. (dragonhead) to various plant densities and compost applications. Compost levels had a promoting influence on most of vegetative growth parameters and accelerated essential oil accumulation and chemical constituents including total carbohydrate and photosynthetic pigments content. Similarly, wider plant spacing showed the greatest effect on growth components and chemical constituents. Generally, the maximum rate of compost (39.6 t/ha) combined with wider distance between plants (40 cm) had a favorable effect on most of growth characters. The same treatment gave the highest mean value for essential oil yield during the first season while the same compost rate combined with the medium distance (30 cm) gave the highest value during the second season. The main constituent of the essential oil was linalool followed by geranial. On the other hand, compost levels combined with different distances had a pronounced effect on the various essential oil constituents. It can be decisived that there is no significant difference between wider distance (40 cm) and medium one (30 cm); so, it can be recommended to apply the maximum level of compost (39.6 t/ha) combined with medium distance. (c) 2006 Elsevier B.V. All rights reserved.