Journal of Environmental Biology

Performance of pea (Pisum sativum L.) with residual phosphorus in phytoremediated heavy metal polluted soil of Jaintia Hills, Meghalaya

V. Sailo* and Sanjay-Swami 

School of Natural Resource Management, College of Post Graduate Studies in Agricultural Sciences, CAU, Umiam-793 103, India

*Corresponding Author Email : sawmteisailo.ss@gmail.com

Received: 13.06.2020                                                                   Revised: 15.11.2020                                                    Accepted: 15.12.2020

Abstract

Aim: The aim of this investigation was to study the impact of residual phosphorus which was previously applied to maize (Zea mays) crop, on the successor pea (Pisum sativum L.) crop in the phytoremediated heavy metal polluted coal mined soil of Jaintia Hills, Meghalaya.

Methodology: A pot culture experiment was carried out during rabi 2017-18 utilizing heavy metals polluted soil already phytoremediated by maize to assess the performance of pea with eleven residual phosphorus levels applied to preceding maize crop viz. 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 mg kg^-1 soil under completely randomized design and replicated thrice. The number of pods per plant was counted for each plant harvested through sequential picking and mean was calculated for each residual phosphorus level. The number of seeds in each pod was counted treatment-wise (residual phosphorus) and the mean value was calculated for each pot. Analysis of plant and soil samples was performed using standard methods.

Results: Even under high heavy metal load, pea proved to efficiently utilize the residual phosphate fertilization, as it promoted grain yield close to the average yield at the highest level of residual phosphorus applied to the preceding maize crop (100 mg kg^-1). The phosphorus concentration in pea straw increased with the increased residual phosphorus, whereas the concentration of Cr, Cd, Ni, Pb and Co followed the reverse trend and it decreased with each increasing level of residual phosphorus. The uptake of heavy metals (Cr, Cd, Ni, Pb and Co) increased up to a certain extent and thereafter followed a decreasing trend both in the straw and seed of the plant. The phosphorus content in soil after harvest of pea ranged from 0.11 to 1.83 mg kg^-1 indicating increased availability of phosphorus with each successive increased level of previously applied phosphorus, whereas a reverse trend was observed in case of heavy metals and the lowest contents were observed at highest level of 100 mg P kg^-1 soil.      

Interpretation: The increasing soil available residual phosphorus maintained by higher phosphorus application rates in the preceding phytoremediating crop i.e. maize may efficiently be utilized for phytoremediating the remaining heavy metals contents of coal mined heavy metals polluted soil, and therefore, almost normal yield levels of pea cv. Arkel grown under normal soil can be achieved with 100 mg kg^-1 soil level of residual P.       

Key words: Heavy metals, Maize, Pea, Residual phosphorus

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