Effect of Organic Fertilization on Growth and Development of the Root System of two Medicinal Plants, oregano (Origanum vulgare L.) and milk thistle (Silybum marianum L. Gaertn.)

Abstract

Field experiment was conducted in western Greece to determine the effects of organic fertilization on root growth of medicinal plants oregano (Origanum vulgare L.) and milk thistle (Silybum marianum L. Gaertn.). The experimental design was completely randomized with four replications. Two treatments were applied; compost 2000 kg ha-1 (F1) and compost 4000 kg ha-1 (F2). The results indicated that the soil properties were influenced by organic fertilization. The highest organic matter and total nitrogen content were found under F2 treatment. Also, F2 treatment improves soil porosity. Moreover, there were significant differences in root growth between fertilization treatments. For both medicinal plants the highest root length density, root mass density and root surface density were found under F2 treatment. Furthermore, there were significant differences in arbuscular mycorrhizal (AMF) root colonization between fertilization treatments. The greatest values were observed for F2 treatment. The highest AMF root colonization was found for oregano. A positive correlation was found between AMF root colonization and root surface density. Our results indicated that oregano and milk thistle root growth was improved with increasing compost application rates.