Leaf Gas Exchange, Dry Matter Partitioning, and Mineral Element Concentrations in Mango as Influenced by Elevated Atmospheric Carbon Dioxide and Root Restriction

Abstract

The effects of atmospheric CO 2 enrichment and root restriction on net CO 2 assimilation ( A ), dry mass partitioning, and leaf mineral element concentrations in `Kensington' and `Tommy Atkins' mango ( Mangifera indica L.) were investigated. Trees were grown in controlled-environment glasshouse rooms at ambient CO 2 concentrations of 350 or 700 μmol·mol -1 . At each CO 2 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 CO 2 were more efficient at assimilating CO 2 than trees grown in 700 μmol·mol -1 CO 2 . However, total plant and organ dry mass was generally higher for plants grown at 700 μmol·mol -1 CO 2 due to increased A as a result of a greater internal partial pressure of CO 2 ( Ci ) in leaves of plants in the CO 2 enriched environment. Root restriction reduced A resulting in decreased organ and plant dry mass. In root-restricted plants, reduced A and dry matter accumulation offset the increases in these variables resulting from atmospheric CO 2 enrichment. Atmospheric CO 2 enrichment and root restriction did not affect dry mass partitioning. Leaf mineral element concentrations were generally lower for trees grown at the higher ambient CO 2 concentration, presumably due to a dilution effect from an increased growth rate.