Working Toward A Micropropagation Technique For North American White Oaks
Oaks have an important role in landscape horticulture and urban forestry. There are numerous species native to a variety of habitats in North America and they readily hybridize between species within a taxonomic section (e.g. the white oak or red oak section). Yet their valuable characteristics have been severely underused due to the difficulty of vegetative propagation. Grafting often results in delayed incompatibility and cuttings do not easily root. Hybrids and unique types of oaks are rarely introduced to the nursery industry. This research investigated the potential for using micropropagation as a technique for the asexual propagation of oaks. Immediate challenges were to obtain responsive explants that produced elongated shoots (shoots [GREATER-THAN OR EQUAL TO] 1 cm), to control contamination during the initiation phase and to subculture shoots to achieve multiplication. Results showed 1 mg l-1 BA (6-benzylaminopurine) in Woody Plant Medium to have a significant effect (P<0.0001) on obtaining responsive explants from young white oak stock plants. GA3 (Gibberellic acid) added to the growth media was not beneficial for inducing shoot elongation in slow growing or unresponsive explants. Exogenously applied GA3 used in conjunction with BA in the media may help shoot elongation. Only one subculture was achieved as the multiplication phase proved problematic with shoots arresting in growth and browning. The concentration of BA (1.0 mg l-1 or 0.5 mg l-1) did not have a significant effect on shoot length or number during the multiplication phase. Overall, obtaining responsive explants proved successful and more research is needed to further develop the process.