Effect of Spacing on Growth, Yield and Chemical Composition of Stevia Plants (Stevia rebaudiana Bert.)

The aim of this study was to determine the effect of plant spacing on the growth, yield and chemical composition of stevia grown in Poland. The variable factor was spacings of 50 cm x 30 cm, 45 cm x 25 cm and 30 cm x 30 cm. Seedlings were planted during the first ten days of June, and the plant material was harvested between the 10th and 20th of September. In July and September, seedlings were subjected to biometric measurements, and plant samples were taken for chemical analyses. Plants grown at 50 cm x 30 cm spacing were characterised by an increased content of reducing sugars, nitrates, phosphorous, potassium and magnesium, but the yield of the herb and leaves was smallest. The greatest yield of the herb and leaves was found for the 30 cm x 30 and 45 cm x 25 cm spacings with the lowest mass of single plants. Leaves from plants grown in the 30 cm x 30 cm spacing were also characterised as having the greatest concentration of dry mass and phenolic compounds and the lowest concentration of phosphorus and magnesium. Spacing did not significantly affect the biometric parameters of the plants in July, but in September, a difference was observed in the lateral width and total number of shoots. Spacing did not affect the plant pigment contents in the leaves of stevia.