Investigation of rooting ability of poplar interspecific hybrids (Populus alba x P. euphratica) through apical meristem culture

Much attention being paid on silviculture of different Populus species and their inter-specific hybrids have increased hopes for wood yield increments in Iran. For the mentioned reason much efforts have been done on hybridization between various Populus species in order to broaden their genetic basis, as well as utilizing their entire potentials and extending their ecologic zones. However, experiences of researchers have shown that produced hybrids have increased new genetic variability, as well as differences with their parental species, by which new high yielding cultivars were introduced. This research was performed in order to quantify possible differences between new inter-specific hybrids between Populus alba as female parent and P. euphratica as male parent based on their rooting capability to be introduced as a criteria for selecting new high yielding poplar genotypes.
Producing a number of inter-specific hybrids between two poplar species, Populus euphratica and P. alba, vegetative propagation of three of the best hybrids through apical meristem culture was performed. First active vegetative buds were harvested and surface sterilized by dipping in 20% sodium hypochlorite for five minutes. Then one to two mm of the apical tips were inoculated on half-MS medium containing IBA and BA of 0.01 and 0.5 mg/l respectively. The explants were maintained in growth chamber at 24 ±1°C and 16/8 hr photoperiod for 60 days. DKW with 0.5 mg/l of BAP, 0.5 mg/l of 2iP and 0.5 mg/l IBA were used as proliferation medium. Propagated shoots were inoculated on two rooting media, DKW and ACM. Data were recorded on characteristics such as freshness, number and length of shoots and roots on rooted plantlets and analyzed based on a factorial experimental model.
The studied hybrids were significantly different based on freshness, stem length and rooting ability, in such a way that one of the hybrids even highly rooted at proliferation stage. The hybrid was strongly different with the others studied hybrids at rooting stage by producing much more roots than others as well as producing longer shoots.
The studied hybrids differentiated significantly by meristem culture based on vegetative characteristics such as rooting ability and shoot length. Superior hybrids with specific rooting ability may be selected based on the observed differences between the studied genotypes..