N-Fertilizer (Urea) Enhances the Phytoextraction of Cadmium through Solanum nigrum L.

Arosha Maqbool,Muhammad Saleem Arif,Mohamed M. Abdel-Daim,Muhammad Riaz,Saad Alkahtani,Shamaila Noreen,Afzal Hussain,Tahira Yasmeen,Muhammad Rizwan,Shafaqat Ali

doi:10.3390/ijerph17113850

Abstract

Heavy metal contamination is currently a major environmental concern, as most agricultural land is being polluted from municipal discharge. Among various other pollutants, cadmium (Cd), one of the most harmful heavy metals, enters into the food chain through the irrigation of crops with an industrial effluent. In the present study, a pot experiment was designed to assess the effect of different nitrogen (N)-fertilizer forms in the phytoremediation of Cd through Solanum nigrum L. Two types of N fertilizers (NH4NO3 and urea) were applied to the soil in different ratios (0:0, 100:0, 0:100, and 50:50 of NH4NO3 and urea, individually) along with different Cd levels (0, 25, and 50 mg kg−1). The plants were harvested 70 days after sowing the seeds in pots. Cadmium contamination significantly inhibited the growth of leaves and roots of S. nigrum plants. Cadmium contamination also induced oxidative stress; however, the application of N-fertilizers increased the plant biomass by inhibiting oxidative stress and enhancing antioxidants’ enzymatic activities. The greatest plant growth was observed in the urea-treated plants compared with the NH4NO3-treated plants. In addition, urea-fed plants also accumulated higher Cd concentrations than NH4NO3-fed plants. It is concluded that urea is helpful for better growth of S. nigrum under Cd stress. Thus, an optimum concentration of N-fertilizers might be effective in the phytoremediation of heavy metals through S. nigrum.

Highlights

Anthropogenic activities have resulted in environmental degradation and a significant reduction in soil productivity [1]
Stunted growth was observed in the control group, while no such signs were observed in the Stunted growth was observed in the control group, while no such signs were observed in the NN-fertilizer-treated group
Our results revealed that superoxide dismutase (SOD), POD, CAT, and ascorbate peroxidase (APX) activities of S. nigrum were recorded in response to Cd stress

Summary

Introduction

Anthropogenic activities have resulted in environmental degradation and a significant reduction in soil productivity [1]. Abiotic stress, such as heavy metals, extreme temperature, and salinity, affect crop production [2]. Industrial discharge, sewage sludge, mining, and agriculture have become major precursors of heavy metal discharge into water bodies and soil [3]. Compared with all other heavy metals, cadmium (Cd) is considered lethal once it becomes part of the food cycle. Around 70% of the dietary intake of Cd occurs from consuming the vegetables and grain crops grown in Cd-contaminated soils [4]. Cadmium is highly toxic for plant growth and seed germination, in addition to the antioxidant, photosynthetic, and enzyme activities [5].

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Results

Discussion

Conclusion