The aim of our research was to prolong the in vitro culture period in species Haworthia
cymbiformis, Exacum affine and Drosera rotundifolia.
For Drosera rotundifolia two layers of media were used, both hormone-free MS. The
liquid medium was poured over the plants that have been grown in agar gelled media for two
months. The resulting plantlets have been counted and weighed after nine more months of in
vitro culture. For Exacum affine 3 experimental variants were used. The liquid media (approx.
200 ml) were poured over the plantlets grown on solid media for 2 months. After a year of in
vitro culture the in vitro-grown plantlets were weighed and the shoots were counted. In the
case of Haworthia cymbiformis calli were inoculated onto two variants of medium: Hormonefree
MS with 10 g/l activated charcoal and without liquid medium and hormone-free MS onto
which liquid medium (approx. 50 ml) was added. The calli regenerated a large number of tiny
plantlets. The plantlets were counted after 9 months of in vitro culture. The results are
presented in Table 1 and fig.1,2,3.