The Effects of Light and Temperature on Germination of Stevia (Stevia rebaudiana BERT.) Seeds

Abstract

The Stevia rebaudiana (Bert.) Bertoni is a perennial herbaceous plant and belongs to family of Asteraceae(Compositae). The contents of S. rebaudiana (Bert.) Bertoni consist mainly non-caloric stevioside and rebaudioside Asweeteners. Low seed germination is an important problem in stevia cultivation. Therefore in this study, the effects of lightand temperature on germination performance of stevia seeds were studied. Stevia rebaudiana seeds were treated with twolights (light/darkness) and four different temperatures (15 ºC, 20 ºC, 25 ºC, 30 ºC). For each treatment, 50 seeds werecounted and placed into petri dishes. Experiments were conducted as a randomized complete design method with threereplicates. Germination was started within 6 to 10 days depending on the treatments. The highest seed germination rate(71%) was observed in darkness/25 ºC temperature and followed by darkness/20 ºC (68%) and light/25 ºC (67%). On theother hand, the lowest seed germination rate (31%) was obtained from 15 ºC in both light and dark conditions and followedby darkness/30 ºC (43%) and light/30 ºC (49%). The results showed that lower (15 ºC) and higher (30 ºC) temperaturessignificantly decreased the germination rates of stevia independently from the light treatments.