Heritability for yield, leaf:stem ratio and stevioside content estimated from a landrace cultivar of Stevia rebaudiana

Stevia rebaudiana (Bert.) Bertoni is a herbaceous perennial native to the highlands of Paraguay. A number of compounds in the leaf tissue have a potential food use as low-calorie sweeteners. The purpose of this work was to determine if sufficient genetic variability was present in a landrace cultivar of stevia to allow selection of lines with agronomic and chemical properties suitable to local production conditions. Leaf yield, leaf:stem ratio and stevioside concentration were all found to be highly heritable. Leaf-yield levels were comparable to those in other stevia-producing areas. Stevioside concentration was higher, probably as a result of production under long days. These initial results also show that improvement of stevia through selection is possible and that it has potential for production in southwestern Ontario.