Impact of increasing atmospheric concentration of carbon dioxide on coffee leaf rust and coffee plant growth

Abstract

The objective of this work was to evaluate the effect of increasing the atmospheric concentration of carbon dioxide on plant growth and leaf rust severity (caused by Hemileia vastatrix) on coffee (Coffea arabica). The 'Obatã IAC 1669‑20' and 'Catuaí Vermelho IAC 144' cultivars, moderately resistant and susceptible to the disease, respectively, were used. The treatments consisted of 400 and 508 μmol mol^‑1 atmospheric CO₂, in two types of open-top chambers (OTC). Plants of the two cultivars, grown in OTCs with addition of CO₂, showed increased leaf area, and increased growth rate of height and stem diameter, in comparison with plants in OTCs with ambient CO₂ concentration; however, the cultivars did not differ for leaf‑wax content. On 'Catuaí Vermelho IAC 144', rust severity reduced at increased CO₂ concentration, for number of lesions, lesioned leaf area, number of sporulated lesions, sporulated leaf area, percentage of lesioned area, and area under disease progress curve; however, on 'Obatã IAC 1669‑20', the disease severity did not vary. The incidence of lesioned leaves per plant, latent period, urediniospore germinations, and appressorium formation are not changed by the 508 μmol mol^‑1 CO₂ dose in both cultivars.