Effects of atmospheric CO2 enrichment on chlorophyll and nitrogen concentrations of sour orange tree leaves

摘要: Since 18 November 1987, eight sour orange (Citrus aurantium L.) trees have been maintained under well watered and fertilized conditions within four clear-plastic-wall open-top enclosures, two of which continuously supplied with ambient air approximately 400 μl l−1 CO2 enriched to 700 CO2. At weekly intervals throughout years 4–7 this long-term experiment, we measured chlorophyll a contents 60 leaves on each the hand-held meter that was specifically calibrated for our study. bi-monthly intervals, also areas, dry weights nitrogen 68 from tree. Expressed per-unit-leaf-area basis, CO2-enriched contained 4.8% less than exposed air. Because their greater leaf numbers, however, 75% more total ambient-treatment trees; productivity 175% greater. Consequently, although were slightly lowered by atmospheric enrichment in use efficiencies greatly enhanced.