Akademik Veri Yönetim Sistemi
FRESENIUS ENVIRONMENTAL BULLETIN, cilt.30, sa.9, ss.10522-10529, 2021 (SCI-Expanded)
The leaves of the stevia ( Stevia rebaudiana Bertoni) plant, a perennial plant from the Asteraceae family, contain glycosides such as Stevioside, Rebaudioside A, B, C, D, E and Dulcoside A, which are sweeter than sucrose. However, among these glycosides, Stevioside (Stv) and Rebaudioside A (Reb A) give the plant the main sweetening properties. Especially, the higher the amount of Reb A in the leaves, the higher the sweetener quality of the products. This sweetener is known to be 200-300 times sweeter than sugar. Since the sweetener obtained from the stevia does not need insulin secretion during digestion, it can be used by diabetics. It is also preferred in diet products due to its zero-calorie feature. Adaptation studies carried out in Antalya conditions have shown that stevia can be cultivated perennially. It is important to know the change of Reb A amount and Reb A / Stv ratio, which are very important for the sweetener quality of the stevia leaves, according to the plant's development period (ontogenetic) and the position of the leaves in the plant. In order to determine the most suitable harvest time, trial samples were taken on 20 July, 5 August, 20 August, 5 September and 20 September 2020 and the amounts of Reb A and Stv were determined. Also, Reb A and Stv analyses were performed in the lower, middle and upper leaf samples on the same plant. It is found that the 4th harvest time (September 5th) is superior to other harvest times in terms of both high leaf yield and high SGs amount in Antalya conditions. At this harvest date, Reb A / Stv ratio, which is important for leaf quality, was found to be high as well. On the other hand, the change in Reb A / Stv ratios in lower, middle and upper leaves at different harvest times was found to be significant.