Leaf gas exchange, dry matter partitioning, and mineral element concentrations in mango as influenced by elevated atmospheric carbon dioxide and root restriction

The effects of atmospheric CO₂ enrichment and root restriction on net CO₂ assimilation (<em>A</em>), dry mass partitioning, and leaf mineral element concentrations in `Kensington' and `Tommy Atkins' mango (<em>Mangifera indica</em> L.) were investigated. Trees were grown in controlled-environment glasshouse rooms at ambient CO₂ concentrations of 350 or 700 μmol·mol^-1. At each CO₂ concentration, trees were grown in 8-L containers, which restricted root growth, or grown aeroponically in 200-L root mist chambers, which did not restrict root growth. Trees grown in 350 μmol·mol^-1 CO₂ were more efficient at assimilating CO₂ than trees grown in 700 μmol·mol^-1 CO₂. However, total plant and organ dry mass was generally higher for plants grown at 700 μmol·mol^-1 CO₂ due to increased <em>A</em> as a result of a greater internal partial pressure of CO₂ (<em>Ci</em>) in leaves of plants in the CO₂ enriched environment. Root restriction reduced <em>A</em> resulting in decreased organ and plant dry mass. In root-restricted plants, reduced <em>A</em> and dry matter accumulation offset the increases in these variables resulting from atmospheric CO₂ enrichment. Atmospheric CO₂ enrichment and root restriction did not affect dry mass partitioning. Leaf mineral element concentrations were generally lower for trees grown at the higher ambient CO₂ concentration, presumably due to a dilution effect from an increased growth rate.