Enhanced Phytoremediation of Cadmium-Contaminated Soil by Parthenium hysterophorus Plant: Effect of Gibberellic Acid (GA_3) and Synthetic Chelator, Alone and in Combinations

摘要

The roles of gibberellic acid (GA_3) and ethylenediaminete-traacetic acid (EDTA) in phytoremediation of cadmium (Cd)-contaminated soil by Parthenium hysterophorus plant was investigated. GA_3 (10~(-9), 10~(-7), and 10~(-5) M) was applied as a foliar spray. EDTA was added to soil in a single dose (160 mg/kg soil) and split doses (40 mg/kg soil, four split doses). GA_3 and EDTA were used separately and in various combinations. P. hysterophorus was selected due to its fast growth and unpalatable nature to herbivores to reduce the entrance of metal into the food chain. The Cd phytoextraction potential of the P. hysterophorus plant was evaluated for the first time. Cd significantly reduced plant growth and dry biomass (DBM). GA_3 alone increased the plant growth and biomass in Cd-contaminated soil, whereas EDTA reduced it. GA_3 in combination with EDTA significantly increased the growth and biomass. The highest significant DBM was found in treatment T3 (10~(-5) M GA_3). All treatments of GA_3 or EDTA significantly enhanced the plant Cd uptake and accumulation compared with control (C1). The highest significant root and stem Cd concentrations were found in the combination treatment Til (GA_3 10~(-5) M ＋ EDTA split doses), whereas in leaves it was found in the EDTA treatments. Cd concentration in plant parts increased in the order of stem ＜ leaves ＜ roots. The combination treatment T9 (GA_3 10~(-7) M ＋ EDTA split doses) showed the significantly highest total Cd accumulation (8 times greater than control C1, i.e., only Cd used). The GA_3 treatments accumulated more than 50% of the total Cd in the roots, whereas the EDTA treatments showed more than 50% in the leaves. Root dry biomass showed a positive and significant correlation with Cd accumulation. GA_3 is environment friendly as compared with EDTA. Therefore, further investigation of GA_3 is recommended for phytoremediation research for the remediation of metal-contaminated soil.