Effects of spacing and harvesting time on herbage yield and quality

Thyme (Thymus vulgaris L.) is member of Lamiaceae family, which distributes in different areas of Meditranea and Asia. Thyme volatile phenolic oil has been reported to be among the top 10 essential oils, showing antibacterial, antimycotic, antioxidative, natural food preservative, and mammalian age delaying properties. It has been known that agronomical factors have a great effect on both quality and quantity of essential metabolites. For this reason, it is necessary to determine optimum levels of agronomical factors affecting plant growth and production. Planting space and time of harvesting are the most important agronomical factors. This study has been conducted in Research farm of ACECR, Institute of Medicinal Plants & Natural Products Research along 1999-2000 on the base of factorial experiment in randomized complete block design with three replications. Thyme is cultivated in rows of 50 cm apart with inter-row spacing of 15, 30 or 45 cm. Plants are harvested in three stages, i.e. the beginning of blooming, full blooming and fruit set. In order to study the effects of plants space and time of harvesting, plant height, plant diameter, yields of dry and fresh herbage, content (%) and yield of oil, thymol and carvacrol were measured. Planting space had significant effect on plant diameter (P < 0.05) and very significant effect (P < 0.01) on other measured parameters except oil content, which was not significant. Time of harvest had significant effect on yield of fresh herbage, content of oil and content of carvacrol (P < 0.05). Its effect on other parameters was very significant (P < 0.01) except dry herbage and oil yield. The maximum yield of dry and fresh herbage, yield and content of oil and thymol yield were obtained in 15 cm space and beginning of blooming stage. Maximum thymol content was observed in the beginning of blooming and 45 cm space. However, 15 cm spacing and harvesting in the beginning of blooming was the best treatment in respect of yield of dry matter, oil and thymol per unit area. (C) 2003 Elsevier B.V All rights reserved.