Abstract
The present study aimed to optimize the micropropagation of lacy tree philodendron using shoot tip explants. Axillary shoot regeneration was investigated in Murashige and Skoog (MS) medium with different types and concentrations of plant growth regulators, varied levels of MS medium salt strength, sucrose concentration, and light intensity and culture type. Adding 6-benzylaminopurine (BAP; 1 mg center dot L-1) significantly increased shoot multiplication compared with other cytokinins, and the combination of cytokinins and auxins [indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA)], yielded more shoots than cytokinins alone, with the greatest number of axillary shoots (11.4 per explant) obtained using both BAP (1 mg center dot L-1) and IBA (0.5 mg center dot L-1). In addition, the use of half-strength salt concentrations significantly reduced shoot multiplication, and high sucrose concentrations (>30 g center dot L-1) reduced explant growth. High light intensity also reduced shoot multiplication and growth, owing to photoinhibition, and shoot multiplication was more efficient in gelled culture, whereas shoot growth was greater in liquid/bioreactor culture. The best rooting success (100%) and greatest root number and fresh weight were obtained using MS medium supplemented with NAA (1-2 mg center dot L-1). The resulting plantlets were successfully acclimatized, with a survival rate of 100%, and were morphologically similar to the mother plant.