Vegetative propagation by stem cuttings and container production from stem cuttings of eastern redcedar (Juniperus virginiana L.)

Abstract

Eastern redcedar (ERC) is an important tree for windbreaks in the Great Plains. Despite ERC spreading from desired locations to become a nuisance tree, seedling demand remains for windbreak and conservation purposes. Clonal propagation of ERC male plants as a substitute for seedlings has been suggested to slow its spread. The goal of this research is to 1) develop procedures for producing male ERC from stem cuttings, 2) investigate the use of a wire staff from a marking stake as an iron source in producing ERC, and 3) compare the use of controlled release fertilizers with different release rates to continuous liquid feeding for the production of container grown ERC from stem cuttings. Hardwood, softwood, and semi-hardwood stem cuttings from juvenile stock plants were treated with solutions of indole-3-butyric acid (IBA) combined with naphthalene acetic acid (NAA) to evaluate rooting potential. Rooting percentage of hardwood and semi-hardwood cuttings was unaffected by the auxins (48% and 3%, respectively). However, softwood cuttings treated with NAA had reduced rooting compared to untreated cuttings (15% and 29%, respectively). The number of roots per rooted cutting was generally enhanced by the application of NAA. Both hardwood and softwood cuttings had increased root number per rooted cutting when NAA was applied. Rooting percentage of hardwood cuttings from male trees treated with increasing concentrations of NAA had an increasing quadratic response to the auxin. Root number, however, was unaffected. In a greenhouse study, the nutrient release of iron using a marking flag staff and three different release rates of controlled releaser fertilizer in soilless substrate was monitored over 13 weeks. Analysis of substrate solution determined nutrient composition, pH, and electrical conductivity (EC). The addition of the wire staff in the soilless substrate increased the pH and decreased the EC of the substrate solution compared to the control. Controlled release fertilizer impacted pH and increased EC relative to the control. EC among the release rates was similar over 13 weeks. In separate experiments, rooted stem cuttings of ERC were subjected to different fertilizer treatments based on the Kansas Forest Service (KFS) fertility program: the KFS blend, KFS blend supplemented with chelated iron (10% DTPA), and KFS blend with a wire staff or three different release rates of controlled release fertilizer and a water-soluble continuous feed fertilizer to determine nutrient impact on substrate pH, EC, growth, and nutrient composition over the course of 21 and 22 weeks respectively. Although tissue analysis revealed iron was highest in the chelated iron treatment, addition of iron in either form had no effect on growth of ERC rooted cuttings, suggesting iron was adequate in all treatments. The controlled release fertilizers and the water-soluble fertilizer had higher EC relative to the control but still within normal range. Tissue analysis showed differences between fertilizer treatments and the control in all macronutrients, but only Mn and Zn of micronutrients. Height and shoot dry weight were most affected by the addition of the controlled release fertilizers and the water-soluble fertilizer, but caliper and root dry weight were unaffected after 22 weeks of treatment. These results suggest controlled release fertilizers, regardless of release rate, can be used successfully in the production of ERC from stem cuttings over 22 weeks, and their effect on plant growth is comparable to a water-soluble fertilizer. These findings suggest the potential of cloning male ERC by vegetative propagation and producing them for conservation purposes is possible.