Effects of Agricultural Techniques on the Quantitative and Qualitative Characteristics of Stevia Rebaudiana Bertoni, under Mediterranean Conditions (Karditsa, Thessaly, Greece)

Worldwide, Stevia cultivation is increasing steadily, with thousands of hectares being exploited with this natural sweetener plant.The present study represents the first largescale field experiment of the performance of Stevia rebaudiana1 (Bertoni) in Greece, allowing the documentation of a wealth of information regarding the response of this species in a Mediterranean environment.Our experiments were conducted during 2008-2009, in a slightly alkaline soil of 7, 6 pH, using a basic 3-3-6 fertilization (N-P-K).We used the Criolla variety and the plants were transplanted at the end of May.We focused particularly on the effect of different planting distances on: the maximum height of plant, the green stem weight, the green leaf weight, the green root weight, the dry stem weight and dry leaf weight.We used six different spacing systems (60x20, 60x40, 75x20, 75x40, 90x40, 90x20cm), for comparison.Our preliminary results indicate a better plant performance in the 75x40cm spacing system.In the spacing system of 60x20cm, the largest stack of plants compared to the remaining spacing systems, resulted in the greatest amount of harvested material, measured in kg of dry leaves weight per hectare.The qualitative analysis of the concentration of steviol glycosides (stevioside and rebaudioside-A),2 revealed that the spacing system 75x40 also provided the largest concentration of glycosides on plant leaves.By contrast, the largest concentration of total glycoside percentage alone was found in the 60x20 spacing system.The plants after harvesting were dried by an innovative method we inspired, using the tobacco dryers (Virginia, Burley) and the results gave us leaves of great color.Our experiments should provide the basis for further studies in the Southern Balkans, providing the necessary information for afull-scale domestic stevia cultivation, with significant economic, cultural, and social benefits for Greece.