Many previous studies show that 5-aminolevulinic acid (5-ALA) promotes the growth and the yield of several crops and vegetables at low concentrations. In this study, the growth of Populus sieboldii treated with 5-ALA was examined. The shoots with 4 leaves were cultured on medium containing IBA(0.05μg/L). After taking roots, the plants were sprayed with 0-4mM 5-ALA solution. The plants were cultured under 16 hours light conditions at 25℃. It was showed that the dry weight of plants treated 1.0 mM 5-ALA were increased to 1.4-fold as compared to the control after 14 days. Especially, the promotive effects of 5-ALA were shown in the length and dry weight of stem significantly. These results suggest that 5-ALA may apply to promote the growth for some woody plants.
