Ahmed Mehmed, Stanimir Enchev and Stanislav Bozhimirov
Agricultural Academy, Agricultural Institute, 9700 Shumen, Bulgaria
Mehmed, A., Enchev, S. & Bozhimirov, S. (2021). Assessment of initial material for stevia selection (Stevia rebaudiana B.). Bulg. J. Agric. Sci., 27 (3), 536–540
The leaves of South American plant – Stevia (Stevia rebaudiana B.) contain low-calorie but highly effective glycosides (stevioside and rebaudiside) that are extracted as a commercial product, which is 300 to 320 times sweeter than sugar and can be safely used by diabetics. The enhanced interest in stevia cultivation (Stevia rebaudiana Bertoni) as a source for natural, non-calorific sweeteners requires constant enrichment of the gene pool of initial material for the selection. Propagation of stevia is carried out by seeds, vegetative and in vitro methods. Seed germination is usually very poor, and vegetative propagation by cutting the stem requires large stocks of stems, and therefore this method is limited. An alternative approach to successfully replicate and maintain stevia is to use in vitro methods.
The soil and climatic conditions in Bulgaria also allow the successful cultivation of S. rebaudiana B., but due to its high sensitivity to low temperatures, stevia in Bulgaria is only grown as an annual plant.
The current study was carried out in 2017 in Agricultural Institute – Shumen (Bulgaria). The used selection material in this study is seedlings of 33 origins, obtained by 3 different methods: from seeds, from stem cuttings and in vitro propagation. Around May 10th when the danger of frosts has passed, the plants are planted in the field at 50/30cm distance.
The selection materials Stevia differ in the evaluated morphological and productive traits. From the comparative tests, the most perspective for effective production were the seedlings from in vitro regenerates. A tendency was established for more stable yields in some stabilized populations as a result of prolonged selection. Based on dry mass yield, the R-3 population was most productive – 115 g. The method for obtaining seedlings did not have a significant effect on the height trait of the plants.
An evaluation of the gene pool of Agricultural Institute – Shumen was made and the perspective stevia origins for fresh and dry leaf mass production were selected.