THE INFLUENCE OF CO2 ENRICHMENT ON GROWTH, NUTRIENT CONTENT AND BIOMASS ALLOCATION OF MARANTHES-CORYMBOSA

Seedlings of Maranthes corymbosa Blume, an evergreen tree of tropical Australia and Indonesia were grown for 32 weeks under conditions of am bient and elevated (700 mumol CO2 mol-1) CO2 in tropical northern Aust ralia. 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 b ranches and specific leaf weight were significantly increased by eleva ted CO2. Root:shoot ratio and foliar P, K, Mg, Mn and Ca levels were u naffected but foliar nitrogen levels were decreased by elevated CO2, N utrient-use-efficiency was unaffected for phosphorus, magnesium, manga nese, calcium and potassium but nitrogen-use-efficiency increased in r esponse to elevated CO2.