Stevia rebaudiana (Bertoni) is the Paraguayan perennial shrub, belongs to Asteraceae family is well investigated and introduced in different regions of the world. The leaves of the stevia plants contain diterpene glycosides – sweet non-toxic dietic substances that are in 100–300 times sweeter than sucrose, which are used in food industry as the substitute of sugar and synthetic sweeteners. Extracts of a stevia have pharmacological effect. The all-toning, hypoglycemic and antigipertensive action, positive influence of a stevia on digestion, suppression of fungal and microbic growth, antineoplastic effect are well known. The effect of duration of photoperiod on the accumulation of dry mass and the content sweet glycosides was studied on 10 genotypes of stevia in the controlled conditions. Samples are analysed by method of a highly effective liquid chromatography with detecting of a signal on a hybrid mass spectrometer. It was revealed that the dry mass of the plants, which were cultivated under 12 and 14- hours photoperiods, authentically didn't differ while under the 16-hour photoperiod it considerably increased in all the studied genotypes. The change of photoperiod from 12 to 16 hours light per day also resulted in increasing of the amount of sweet glycosides in leaves of plants of genotypes studied. A significant variability is seen in the percentage composition of steviol glycosides .The greatest mass of sweet glycosides was accumulated by plants of those genotypes which had higher percentage of sweet glycosides in leaves, but not the greatest dry mass of leaves. The lines of a stevia which are accumulated the greatest dry mass of leaves, and also having high percentage containing sweet glycosides in leaves under the of short and long- day conditions are allocated. The obtained data can form a basis for carrying out the selection of new lines of stevia with valuable properties, adapted to the lighting conditions of the region of cultivation.
Химия растительного сырья (http://journal.asu.ru/index.php/cw/article/view/470)