Effect of Cadmium Pollution on Nitrogen Assimilation and Biomass Accumulation of Vigna unguiculata L
- Post by: sulegumes
- January 8, 2019
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Background and Objective: With the increased soil pollution caused by heavy metals, identifying accessions that are high nitrogen assimilators has a potential in improving soil fertility and increase crop yield. Therefore, the current study aimed at determining the variation in nitrogen assimilation and biomass accumulation of cowpea accessions to cadmium pollution. Materials and Methods: A field experiment was conducted to evaluate the plant nitrogen assimilation and dry weight matter of cowpea accessions in response to cadmium pollution in Benin city located in southern Nigeria. Five cowpea accessions (TVu-91, TVu-92, TVu-93, TVu-95 and TVu-96) were sown in the control (0ESV) and two treatments of cadmium chloride (Cd-2.5ESV and Cd-5ESV), laid out in a randomized block design (RBD) and replicated thrice. The leaves and roots were assessed at 6 and 18 weeks after sowing and (WAS) for total nitrogen, nitrogen assimilated as nitrate-N or ammonia-N form and their percentage. The plants’ biomass accumulation was also determined 20 WAS. Results: From the result, 6 WAS cadmium pollution significantly reduced foliar TN% irrespective of cowpea accession except in TVu-95. Cowpea accessions distributed nitrogen mainly as nitrate-N with the highest values observed in TVu-91 while TVu-96 recorded the highest N% assimilated as nitrate irrespectively of treatment. In addition to this, cadmium pollution reduced the overall foliar yield and plant dry weight of TVu-accessions with increased metal concentration. TVu-92 and TVu-96 in the Cd-2.5ESV and Cd-5ESV were more closely related in their mode of response to cadmium incidence compared to the other accessions. Conclusion: Nitrogen was significantly assimilated more as nitrate-N than ammonium-N and readily distributed to the leaves.
Key words: Cowpea, dry weight matter, high nitrogen assimilators, nitrate, cadmium pollution, dendrogram, ammonia-N form