Section 36
Chapter 35,316

Mist level influences cutting water potential and rooting of stem cuttings of loblolly pine

Lebude, A.; Goldfarb, B.; Blazich, F.; Frampton, J.; Wise, F.

HortScience 38(5): 840


ISSN/ISBN: 0018-5345
Accession: 035315664

Vegetative propagation of loblolly pine (Pinus taeda L.) by stem cuttings is used for multiplying superior full-sib families and elite individuals within superior families. To produce rooted cuttings cheaply and efficiently, propagators must produce rooted cuttings on a large scale. However, this often makes control of the rooting environment a challenge, especially when propagators use rooting environments ranging from greenhouses to direct field setting of cuttings. Therefore, the following research was conducted to define physiological variables that might predict successful rooting among a variety of rooting environments. Specifically, the relationship between mist application and cutting water potential (Y cutting), and the relationship between Y cutting and rooting percentage of stem cuttings in a polyethylene-covered greenhouse was investigated. Six mist regimes were tested in two experiments. One experiment used dormant, hardwood stem cuttings collected in February, cold-stored, and then set in April, while the other experiment used succulent, softwood cuttings, taken and set in June. Seven, 14, 21, 28 and 35 days after setting (DAS), Y cutting was measured destructively, utilizing a pressure chamber, on two cuttings in each plot every 3 hours between 0500 HR and 2300 HR (seven measurements for each day that measurements were recorded). Rooting success was scored 70 DAS for all cuttings and cuttings were considered rooted when they had at least one root? 1 mm. For both experiments, Y cutting was strongly related to the log of mist application. Mean rooting percentages were 73% and 63% for hardwood and softwood cuttings, respectively. Rooting percentage, in both experiments, was related to Y cutting and the square of Y cutting. Rooting increased with increased Y cutting (became less negative), however, as Y cutting continued to increase, rooting declined, suggesting that cuttings may need to experience moderate water deficit for optimum rooting. The curves generated defined a range of Y cutting, specific for each cutting type, which corresponded with the greatest rooting in each experiment. Results serve as a step in defining a range of Y cutting that may be applicable among various rooting environments.

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