Gibberellic Acid Treatment Improved Pyrene Phytoremediation Efficiency of Ridge Gourd (Luffa acutangula (L.) Roxb.) In Soil

Abstract

ABSTRACT The use of plant growth regulators to alleviate PAH phytotoxicity is an alternative choice to increase the efficient of PAH phytoremediation. In this study, the capacity of auxin and gibberellin to enhance the growth and PAH removal of ridge gourd (Luffa acutangula (L.) Roxb.) was determined. Indolebutyric acid (IBA) and gibberellic acid (GA3) at 1 and 10 mg l−1 were applied to ridge gourd by soaking the seeds for 3 h or applied in water to 5 day-olds seedlings that were grown in 100 mg kg−1 phenanthrene- and 100 mg kg−1 pyrene-contaminated soil. The effect of plant growth regulator on PAH removal depended on the application method. IBA-treated plants did not enhance phenanthrene and pyrene biodegradation, while ridge gourd treated with GA3 by soaking and watering enhanced pyrene biodegradation, when compared with the non-treated plant. GA3 could increase the pyrene biodegradation, while GA3 applied with water at a high concentration seemed to retard the plant growth. For plant growth, only the shoot and root fresh weights of ridge gourd in the IBA-soaked treatment were higher than those of the non-treated plant. Watering with 1 mg l−1 GA3 only enhanced the root fresh weight of the ridge gourd while the GA3 application decreased the shoot and root length, especially for the 10 mg l−1 water treatment. IBA application did not increase the PAH biodegradation, while IBA applied by seed soaking at a low concentration could increase the plant fresh weight.