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

Abstract

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.