The Influence of CO₂ Enrichment on Growth, Nutrient Content and Biomass Allocation of Maranthes corymbosa

Abstract

Seedlings of Maranthes corymbosa Blume, an evergreen tree of tropical Australia and Indonesia were grown for 32 weeks under conditions of ambient and elevated (700 μmol CO₂ mol^-1) CO₂ in tropical northern Australia. Seedlings were exposed to ambient temperature, vapour pressure deficit and photon flux density fluctuations. Rates of germination and percentage germination were not affected by elevated CO₂. Total plant biomass, height growth, total plant leaf area, numbers of leaves and branches and specific leaf weight were significantly increased by elevated CO₂. Root:shoot ratio and foliar P, K, Mg, Mn and Ca levels were unaffected but foliar nitrogen levels were decreased by elevated CO₂, Nutrient-use-efficiency was unaffected for phosphorus, magnesium, manganese, calcium and potassium but nitrogen-use-efficiency increased in response to elevated CO₂.