Performance of Stevia rebaudiana Bertoni Genotypes under European Temperate Zone Conditions

Stevia rebaudiana is an interesting crop due to the valuable sweeteners in its leaves. After previous field trials had shown that this genus, with its natural habitat in the subtropics of South America, performed successfully under European temperate zone climate conditions, investigations focused on sweetener quality. Therefore comparative studies with a local selection developed in the course of the field trials and six alternative genotypes were initiated in 2009. For the evaluations of vegetative performance and sweetener yield and quality, expressed as content of rebaudioside A, eight plants per genotype were cultivated in containers and kept under outdoor conditions. The local selection Gawi outyielded the other genotypes tested. However, with regard to sweetener quality it was outperformed by two genotypes providing 140% and 120% higher contents of rebaudioside A, respectively. Furthermore, one of these genotypes had higher leaf yield (10%) and much better leaf-to-stem ratio (110%). These two genotypes are recommended for further studies aiming at improved combinations of yield and quality traits.