Elevated CO2 Accelerates Phosphorus Depletion by Common Bean (Phaseolus vulgaris) in Association with Altered Leaf Biochemical Properties

Phosphorus (P) is a major limiting factor for plant productivity in many ecosystems and agriculture. The projected increase in atmospheric CO2 is likely to result in changes in plant mineral consumption and growth. We studied P depletion by common bean (Phaseolus vulgaris) cultured hydroponically under ambient (377 ± 77 μmol mol−1) or elevated (650 ± 32 μmol mol−1) CO2 in media of low or high P. Under elevated CO2 compared to ambient CO2, the maximum P depletion rate increased by 98% at low P and 250% at high P, and P was depleted about 2-5 weeks sooner; leaf acid phosphatase (APase) activity and chlorophyll content both increased significantly; root-to-shoot ratio increased significantly at high P, although it was unaffected at low P; lateral root respiration rate showed no change, suggesting that CO2 did not affect P depletion via metabolic changes to the roots; the total biomass at final harvest was significantly higher at both low and high P. Our data showed that the increased rate and amount of P depletion during plant growth under elevated CO2 occurred in association with alterations in leaf biochemical properties, i.e., enhanced activities of leaf APase and increased leaf chlorophyll content.