Indole-3-acetic Acid (IAA) Assisted Phyto-extraction Potential of Ipomoea aquatica Exposed to Lead (Pb) Stress

Abstract

Agricultural lands are gradually being contaminated by heavy metals (HMs) obtained from urbanization and human activities. Lead (Pb) is one of the major heavy metals easily enters into food cycle and causes different health abnormalities. So elimination of this dangerous heavy metal from surface water is crucial and in this regard phyto-extraction based phytoremediation is an environmentally safe procedure. Again, this removal process can be amplified through the use of plant growth regulators exogenously. With this aim, an experiment was conducted to know the efficiency of the use of indole-3-acetic acid (IAA) on phyto-extraction of Pb by an aquatic hyper-accumulator plant Ipomoea aquatica. The plants were grown hydroponically with 200ppm Pb treated with 200ppm IAA exogenous spray or mixed with Hoagland solution (HS) or both. The control treatment was HS supplemented with Pb. From the experiment, it was observed that control treatment causes a great reduction in growth parameters as the plants suffered from Pb stress. Treatment with Control + IAA (spray+dissolve), produced tallest plants, longest roots and maximum dry weight. On the other hand, these parameters were got declined in case of Pb treated plants (control). Maximum Pb were accumulated on root, stem followed by leaf for Control + IAA (spray+dissolve). Control treatment caused less Pb accumulation on plant parts. So, maximum bioaccumulation factor (BCF) in root, shoot and leaf were 35.87, 15.33 and 9.15 respectively for Control + IAA (spray+dissolve) treatment. In case of root to shoot translocation, the maximum translocation factor (TF) value (0.5118) was found for Control + IAA (spray) than other treatments. Again for shoot to leaf, the maximum TF value (0.6051) was for HS + HM treatment (Control) and minimum TF value (0.4469) was observed for Control + IAA (spray). From the study, it is confirmed that, exogenous indole-3-acetic acid (IAA) successfully assist Pb phyto-extraction from aquatic bodies and Ipomoea aquatica is a potential heavy metal hyper-accumulating plant.