Improved In Vitro Propagation of Paulownia elongata, P. fortunei and its Interspecific Hybrid P. elongata x P. fortunei

Abstract

Our paper presents an effective micropropagation protocol for Paulownia sp. (P. elongata, P. fortuneiand a P. elongata x P. fortunei hybrid). For in vitro culture initiation, axillary buds as well as seeds wereused. For the multiplication stage, modified Murashige & Skoog (MS) was tested, supplemented with0.5 mg/l BAP (6-benzilaminopurine) and mT (meta-topoline) at the concentrations of 0.5, 0.7 and 1mg/l. The media supplemented with BAP ensured intense proliferation of axillary buds but they alsocaused negative physiological effects (abundant callus growth at the plantlets’ base). In the P. elongata xP. fortunei hybrid as well as in P. elongata 1 mg/l mT ensured the highest proliferation and multiplicationrates, but the plantlets that resulted from the media supplemented with 0.5 and 0.7 mg/l mT were morevigorous and well developed. In P. fortunei 1 mg/l mT ensured average proliferation rates of 9.28 andaverage multiplication rates of 12.92. Wheat starch proved to be a cheap and very effective alternativegelling agent. Ex vitro rooting and acclimatization was very successful by using Jiffy7 pellets and floatingperlite, the latter being a technique elaborated at the Fruit Research Station Cluj, with acclimatizationpercentages of more than 80 % in the 3-5 cm long shoots and more than 60 % in the 2-2.5 cm longshoots. The protocol developed allowed eliminating the in vitro rooting stage in the commonly usedprocesses in the industry.