Mist, substrate water potential and cutting water potential influence rooting of stem cuttings of loblolly pine

摘要

We investigated the influence of cutting water potential (Psi(cut)) on rooting of juvenile hardwood (dormant) and softwood (succulent) stem cuttings of loblolly pine (Pinus taeda L.) propagated under varying substrate water potentials (Psi(sub)) and volumes of mist application. Mist treatment and Psi(sub) contributed to the Psi(cut) of unrooted stem cuttings. When Psi(sub) was held constant across mist treatments, mist treatment contributed strongly to T,ut. Substrate water potential affected rooting percentage when mist treatment was sub-optimal or excessive, otherwise mist treatment had a stronger effect than Psi(sub) on rooting percentage. Cuttings rooted best when subjected to moderate cutting water potentials (-0.5 to -1.2 MPa) during the initial 4 or 5 weeks of the rooting period. Cuttings experiencing either severe water deficit or no water deficit rooted poorly. We conclude that the rooting environment should impose a moderate water stress on loblolly pine stem cuttings to achieve optimum rooting.