Interactive effects of polystyrene microplastics and Pb on growth and phytochemicals in mung bean (Vigna radiata L.)

Interaction of different pollutants can aggravate hazards to biotic components in agroecosystems. Microplastics (MPs) are especially needed to be focused on because of their increasing use in life around the globe. We investigated the interactive impacts of polystyrene microplastics (PS-MP) and lead (Pb) on mung bean (Vigna radiata L.). Toxicity of MPs and Pb directly impeded V. radiata attributes. In combination i.e., M2P2 (40 µM Pb + 4.0 mg L-1 MPs) predominantly reduced the shoot root fresh and dry weights. \ Pb and PS-MP impaired the Rubisco activity and chlorophyll contents. The dose dependent relationship (M2P2) discomposed indole 3-acetic acid by 59.02%. Individual treatments P2 (40 µM Pb) and M2 (4.0 mg L^-1 MPs) respectively instigated a decline (44.07% and 27.12%) in IBA, while ABA was elevated. M2 significantly enhanced the contents of Alanine (Ala), Arginine (Arg), Proline (Pro), and glycine (Gly) by 64.11%, 63%, and 54% compared to control. Lysine (Lys) and Valine (Val) presented a converse relationship with other amino acids. Except for control, a gradual decline in yield parameters were observed in individual and combined applications of PS-MP. Proximate composition of carbohydrates, lipids and proteins also reflected a clear decrease in these compounds after combined application of Pb and MPs. Although, individual doses caused a decline in these compounds but effect of combined doses Pb and PS-MP was highly significant. Our results demonstrated the toxicity effect of Pb and MP in V. radiata attributes that is mainly linked with cumulative physiological and metabolic perturbations. These collective negative impacts of different doses of MPs and Pb on V. radiata would certainly pose serious implications for humans.