Moringa oleifera Lam. leaf extract as bioregulator for improving growth of maize under mercuric chloride stress

The contamination of agriculture soils with heavy metals is increasing due to both natural and anthropogenic activities. This has resulted in lowering the yield and quality of agriculture crops. The aim of the present investigation was to determine the effect of Moringa oleifera (M. oleifera) aqueous leaf extract (MALE) on growth and Hg phytoextraction potential of maize cv. Azam under mercuric chloride (HgCl₂)-induced stress. Soil was contaminated with different concentrations of HgCl₂ (1 and 0.5?mg/kg). The MALE was applied at 5% and 2.5% as seed soaking prior to sowing of seeds in the pots. The M. oleifera leaf was a good source of macronutrients (Na, K, Ca and Mg) and micronutrients (Fe, Zn, Mn, Co and Ni) as well as natural phenolics. The induced HgCl₂ stress significantly reduced seed germination (%), shoot dry weight, root dry weight, chlorophyll content and carotenoids content. The HgCl₂-induced stress was associated with accumulation of phenolics and Hg in roots. The accumulation of Hg in roots was significantly correlated with phenolics content (r?=?.8007, p?=?.000). The exogenous application of MALE significantly ameliorated adverse effects of HgCl₂ stress on maize plants. The accumulation of Hg in roots was significantly increased by MALE. It is inferred from findings of the present investigation that MALE served as bioregulator and can be applied to reduce adverse effects of HgCl₂ on maize. Moreover, MALE can enhance the Hg phytoremediation potential of maize.