MICROPROPAGATION OF PLANTS STEVIA REBAUDIANA BERTONI IN VITRO AND CONTENT OF STEVIOSIDE IN LEAVES AFTER APPLICATION OF GROWTH REGULATORS UNDER FIELD CONDITIONS
ISOLINA ACUNA, ALES NEPOVIM, PAVEL VALlCEK
Abstract
Stevia rebaudiana Bertoni belongs to a group of plants
producing substances utiliza-ble as a non-caloric sweetener on the basis of
glycosides. Among them stevioside mostly occuring is in comparison with glucose
300 times sweeter and is present in leaves in concentration from 3 to 10 % of
dry matter. One possibility how to increase the sweetener content in leaves
is in application of growth regulators of different micro- and macroelements
and growth hormones composition by foliar spraying. Method of micropropagation
in vitro represents with respect to low germination ability of seeds an important
factor of seedlings preparation. For micropropagation in vitro nodal segments
of 6 weeks old seedlings cultivated on MS medium with half macroelements content
and in the presence of growth hormone of auxine character (NAA) in concentration
of 0.01 ppm were used. At the transfer of plants from in vitro into in vivo
conditions to support the root system formation the preparation with 5 % content
of IAA was used. The vitrified plants have been cultivated for one month in
a glasshouse and then planted to the field. Altogether 40 plants cultivated
from seeds in a box were after transplanting to the field exposed to the effect
of growth regulators. As a most effective preparation increasing concentration
of stevioside in leaves proved to be Humiforte in combination with Aminol but
the highest quantity of biomass produced was reached when the growth regulator
with commercial name Melatran was used.
Key words:
stevioside, in vitro, micropropagation HPLC, glucotest.