Impacts of water deficit and post-drought irrigation on transpiration rate, root activity, and biomass yield of Festuca arundinacea during phytoextraction.

Water deficit is a hazardous threat to phytoremediation, while the photosynthetic efficiency of plant leaves can rapidly recover after post-drought irrigation, thereby enhancing the root activity, transpiration rate, and metal accumulation capacity of plants. This study was designed to test whether the phytoextraction effect of drought-stressed Festuca arundinacea could recover to normal levels after post-drought irrigation. Two drought stress levels (D, slight stress and D, moderate stress) were carried out at one of five plant growth stages (G, germinating; G, tillering; G, jointing; G, booting; and G, flowering). The results showed that drought stress, regardless of level, significantly decreased the transpiration rate of F. arundinacea by 38.9%-85.7%. The degree of reduction of this physiological index was significantly higher in DG and DG than in other treatments. The biomass yield and root activity in DG, DG, DG, DG, and DG recovered and even surpassed the normal values after rewatering, suggesting that the detrimental effects of drought stress on F. arundinacea at certain growth stages can be compensated by post-drought irrigation. Drought stress also decreased the Cd uptake capacity of F. arundinacea, and the degree of reduction depended on the stress level and growth stage. Overcompensation for Cd accumulation was observed in DG, DG, DG, and DG after post-drought irrigation. The results indicated that suitable irrigation strategies can improve the phytoextraction effect of F. arundinacea and conserve water resources in practice.