Folic acid-mediated phytoremediation by canola (Brassica napus L.) under mercuric chloride (HgCl2) stress

Morpho-physiological and biochemical attributes of plants are effected by heavy metal toxicity, resulting in production of huge amount of reactive oxygen species. This is the reason, that agricultural production systems are facing a major sustainability problem around the globe. This study reflects the potential of exogenous folic acid (FA) application for mitigating toxic effects of heavy metal on two verieties of Brassica napus L. (V1: super canola and V2: sandal canola). For this purpose, a pot experiment was carried out during winter of 2022–23 at University of Agriculture Faisalabad, Pakistan, in its Old Botanical Garden. We applied three levels of Mercuric chloride (HgCl2) i.e., 0 (control), 50 mM, and 100 mM in soil. Three concentrations of FA: control (spray with distilled water), 0.05 mM (50 µM), and 0.1 mM (50 µM) were implemented by foliar application. Mercury stress significantly decreased the chlorophyll contents, carotenoids contents and relative water contents by 49%, 68% and 36% respectively. The implementation of 50 and 100 µM FA enhanced the grain yield per plant upto 58.99% and 72% respectively, compared with plants which received no application of FA with highest level of mercury. Foliar application of folic acid to Brassica napus L. under heavy metal stress increased in chlorophyll contents and osmoprotectors. Most obvious phytoremediation was observed when we treated Brassica napus L. with 50 mM Mercuric choride and provided with 100 µM of FA in comparison with plants which have been given 0 µM of FA.