The Corymbia and Eucalyptus species eaten by koalas are generally large trees, but these are often unpopular with urban landowners and councils because of the dangers of limbs falling from a great height. We aimed to develop shorter koala food and habitat trees for urban areas by heterografting tall eucalypt species onto rootstocks of shorter species and comparing their survival and growth with homografted trees and control ungrafted trees. In total, 12 of 14 interspecific scion/rootstock combinations were grafted successfully in the nursery but graft compatibility and field survival depended on taxonomic relatedness. The six interspecific combinations that had multiple surviving trees at 5 years after planting were all between species within the same taxonomic section or between a species and its own interspecific hybrid. Almost all trees died from grafts between species in different taxonomic sections. In most cases, the height of surviving interspecific grafted trees did not differ from control intraspecific grafted trees or from ungrafted trees of their scion species. Grafting elicited a ‘thrive or not survive’ response that diminished its usefulness for producing shorter trees. However, one combination, E. moluccana/E. behriana, had field survival of 40% and reduced height (4.0 m vs 9.9 m). These could be valuable habitat trees for koalas and other fauna in urban areas.
Many eucalypt species are difficult to propagate as rooted cuttings. The mineral nutrition of cuttings is a key factor that limits adventitious root induction but little is known about partitioning of nutrients by eucalypt stock plants. This study determined N, P, K, Ca, B, S, Mg, Mn, Zn, Al, Fe and Na concentrations in the root system, pruned hedge and harvested cuttings of stock plants of the eucalypt, Corymbia citriodora. Between 17% and 31% of total plant mass was collected as cuttings at each harvest. The mobile nutrients, N, K and S, were highly concentrated in the cuttings and were removed in high amounts (e.g. 27-46% of total plant N) at each harvest, whereas less-mobile nutrients such as Ca and Zn were less concentrated in the cuttings than other plant parts. Adventitious rooting of eucalypt cuttings has been related to B concentration but this study revealed that B was much more highly concentrated in the hedge than the cuttings. Management of N and K concentrations for shoot production, and B concentrations for adventitious rooting, may be critical for sustaining rooted cutting production by C. citriodora.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.