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Benefits Bestowed Upon Eucalypt Clonal Plantlets by Elevated CO2

Paper Reviewed
Ghini, R., de O. Mac Leod, R.E., Neto, A.T., Cardoso, D.C., Bettiol, W., de Morais, L.A.S. and Vique, B. 2014. Increased atmospheric carbon dioxide concentration: effects on eucalypt rust (Puccinia psidii), C:N ratio and essential oils in eucalypt clonal plantlets. Forest Pathology 44: 409-416.

In reporting their work on the subject, Ghini et al. (2014) begin by noting that eucalypt rust - a debilitating fungal disease - "is a serious threat to the yield of eucalypts and of other species of the Myrtaceae family [trees and shrubs found in the topics, subtropics and temperate Australia]," citing Carnegie and Lidbetter (2012), which disease they say "is believed to be native to South and Central America," citing Alfenas et al. (2005), and which they further describe as "an invasive pathogen threat that was detected in Australia in 2010," citing Carnegie et al. (2010). And, hence, they thought it of significant importance to determine how it might be impacted by the ongoing rise in the atmosphere's CO2 concentration.

Working with both open-top and closed chambers, the seven scientists studied several of the phenomena they thought might possibly be impacted by the ongoing and projected rise in the atmosphere's CO2 concentration. This they did by growing plantlets originating from two eucalypt clones - one derived from E. urophylla [MN 463] and another arising from the interspecific crossing of E. urophylla x E. camaldulensis [VM 01] - at adequate soil fertility and moisture conditions, but at different atmospheric CO2 concentrations in the two sets of chambers, where suspensions of urediniospores of P. psidii that had been collected from infected leaves of E. grandis and multiplied in Malabar plum/rose apple were sprayed on both sides of the plants' leaves.

In reporting their results, the Brazilian researchers state that in both open- and closed-top chambers, "increased atmospheric CO2 concentrations resulted in a decrease in rust pustules per leaf, uredinia [fruiting bodies] per leaf area, spores per uredinia and area under the disease progress curve in VM 01 (hybrid) clonal plantlets." They also indicate that "plant growth of the two clones was stimulated by up to 23% in height and 26% in stem diameter in the open-top chambers [enriched by ~100 ppm CO2] and by 18% for both clones in the closed chambers [enriched by ~300 ppm CO2]." And in light of these several observations, they conclude that "increased concentrations of atmospheric CO2 favorably impacted eucalypt growth and reduced rust severity, while not influencing the production of essential oils," all of which are very favorable findings.

Alfenas, A.C., Zauza, E.A.V., Wingfield, M.J., Roux, J. and Glen, M. 2005. Heteropyxis natalensis, a new host of Puccinia psidii rust. Australasian Plant Pathology 34: 285-286.

Carnegie, A.J. and Lidbetter, J.R. 2012. Rapidly expanding host range for Puccinia psidii sensu lato in Australia. Australasian Plant Pathology 41: 13-29.

Carnegie, A.J., Lidbetter, J.R., Walker, J., Horwood, M.A., Tesoriero, L., Glen, M. and Priest, M.J. 2010. Uredo rangelli, a taxon in the guava rust complex, newly recorded on Myrtaceae in Australia. Australasian Plant Pathology 39: 366-463.

Posted 30 March 2015