The effect of seven concentrations of two carbohydrate sources were compared to determine the best source and the most suitable source and concentration for micropropagation of some Hosta cultivars: H. 'Gold Haze', H. 'Gold Drop' and H. 'Dew Drop'. 0, 5, 10, 20, 30, 40 and 50 g/1 sucrose or glucose were added to a MS basic medium supplemented with 3 mg/1 kinetin and 0.1 mg/1 IAA. For 'Gold Haze' 40 g/1 sucrose proved to be the best source and concentration, the proliferation ratio was 15 shoots per explant. Thirty g/1 sucrose concentration was the optimum for 'Gold Drop', the proliferation rate was 14.6 shoots per explant. In 'Dew Drop,' the best results were obtained with 30 g/1 sucrose but 40 g/l sucrose gave good results too. Both cultivars rooted well on these media. On glucose containing media, very low propagation rates were found in all concentrations and all examined cultivars.
Two urban stress tolerant Tilia clones were selected by the Department of Floriculture and Dendrology. The mother trees of the Observed clones were found in an alley of linden trees, settled on a traffic island of a busy two-lane road.
Tilia hybrid 'Saint Stephen' has a beautiful cone-shaped crown, the leaves are bright green and they keep their green colour for much longer time than the leaves on the other trees in the alley. In the nursery the Tilia hybrid 'Saint Stephen' was budded on T. cordata, T. platyphyllos and T. argentea and it had good compatibility with every rootstock. The average height of the one year old buddings was 200 cm and the buddings kept their good growing capacity in the following years as well. They had an outstanding growing capability comparing with the other Tilia cultivars.
Tilia platyphyllos 'K3' clone has similar cone-shaped crown. The growing vigor and urban stress tolerance seems to be better than Tilia hybrid 'Saint Stephen'.
The process of in vitro rooting and the anatomical characters of in vitro and ex vitro leaves and roots of Prunus x davidopersica 'Piroska' were studied. Best rooting percentage (50%) and highest root number (5.0) was achieved in spring on a medium containing 0.1 mg/I NAA + 30 g/1 glucose. At the end of rooting the parenchyma of the in vitro leaves was more loose and spongy, than during the proliferation period. In the first newly developed leaf of an acclimatised plant, the parenchyma was much more developed, contained less row of cells and less air space too, compared to the leaves developed in the field. The in vitro developed root had a broad cortex and narrow vascular cylinder with less developed xylem elements, but at the end of the acclimatisation the vascular system became dominant in the root.