Effect of phosphorus supplementation on growth, nutrient uptake, physiological responses, and cadmium absorption by tall fescue (Festuca arundinacea Schreb.) exposed to cadmium

Abstract

Cadmium is a common heavy metal pollutant. In some plants, its absorption is inhibited by exogenous phosphorus. Here, the effect of P supplementation on the growth of tall fescue exposed to Cd was evaluated in a hydroponic culture experiment. Plants were exposed to five concentrations of P (0, 0.25, 0.5, 0.75, and 1.0 mmol L-1) and three concentrations of Cd (50, 100, and 150 mg L-1), and plant growth, Cd content, absorption, physiological characteristics, and nutrient accumulation were investigated. P supplementation significantly reduced the Cd content, Cd translocation factor(TF), Cd removal efficiency, plant P absorption, chlorophyll content, glutathione levels, glutathione reductase levels, and superoxide dismutase (SOD) activity in tall fescue under Cd stress (P < 0.05). Moreover, it increased the vertical growth rate and biomass of tall fescue. At a constant P concentration, the biomass and vertical growth rate significantly decreased with an increasing Cd concentration, and the shoot Cd content, SOD activity, and TF significantly increased (P < 0.05). High P supplementation (0.75 and 1.0 mmol L-1) ameliorated the damage caused by 150 mg L–1 Cd stress, and the biomass, vertical shoot and vertical root growth rates were increased by 72.06–82.06%, 250.00–316.67%, 300.00–312.00%, respectively. In the plants subjected to 50 mg L–1 Cd stress, 0.5 mmol L-1 P supplementation enhanced biomass, vertical shoot and vertical root growth rates by 29.99%, 20.41%, and 21.43%, respectively, and reduced the Cd content in shoots (45.85%) and roots (9.71%). Except for the total potassium content and catalase activity, different concentrations of Cd negatively affected all parameters tested. Such negative effects were limited by P supplementation. Optimizing the nutrient composition and concentrations could minimize the potential negative impacts of Cd on plant growth.