Changes in the Levels of Total Soluble Proteins and Sugars During Leaf Ontogeny in Stevia rebaudiana Bert.

Leaf d. wt and the levels of soluble sugars and proteins showa two-phase development during leaf growth in Stevia rebaudiana.The initial large increases in leaf size are due mainly to waterintake up to an area of around 9–10 cm². Increases inabsolute protein content were initially slow though in the secondphase increased it rapidly with dry matter and soluble sugarcontent. In relative terms, however, the concentration of free sugarsdeclined throughout leaf growth. The data indicate that leafprotein synthesis is most probably dependent upon a carbon supplyfrom in situ photo synthesis which only becomes significantat 80 per cent of full leaf area. Stevia rebaudiana Bert., leaf ontogeny, protein content, sugar content