title: Contrasting effects of biochar, compost and farm manure on alleviation of nickel toxicity in maize (Zea mays L.) in relation to plant growth, photosynthesis and metal uptake.
abstract: Nickel (Ni) toxicity in agricultural crops is a widespread problem while little is known about the role of biochar (BC) and other organic amendments like farm manure (FM) from cattle farm and compost (Cmp) on its alleviation. A greenhouse experiment was conducted to evaluate the effects of BC, Cmp and FM on physiological and biochemical characteristics of maize (Zea mays L.) under Ni stress. Maize was grown in Ni spiked soil without and with two rates of the amendments (equivalent to 1% and 2% organic carbon, OC) applied separately to the soil. After harvest, plant height, root length, dry weight, chlorophyll contents, gas exchange characteristics and trace elements in plants were determined. In addition, post-harvest soil characteristics like pHs, ECe and bioavailable Ni were also determined. Compared to the control, all of the amendments increased plant height, root length, shoot and root dry weight with the maximum increase in all parameters by FM (2% OC) treatment. Similarly, total chlorophyll contents and gas exchange characteristics significantly increased with the application of amendments being maximum with FM (2% OC) application. Amendments significantly increased copper, zinc, manganese and iron concentrations and decreased Ni concentrations in the plants. The highest reduction in shoot Ni concentration was recorded with FM (2% OC) followed by BC (2% OC) being 73.2% and 61.1% lower compared to the control, respectively. The maximum increase in soil pH and decrease in AB-DTPA extractable Ni was recorded with BC (2% OC) followed by FM (2% OC). It is concluded that FM (2% OC) was the most effective in reducing Ni toxicity to plants by reducing Ni uptake while BC (2% OC) was the most effective in decreasing bioavailable Ni in the soil through increasing soil pH. However, long-term field studies are needed to evaluate the effects of these amendments in reducing Ni toxicity in plants.
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
authors.forename: Muhammad Zia-Ur
authors.initials: MZ
authors.lastname: Rehman
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan. Electronic address: mrazi1532@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rizwan
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Shafaqat
authors.initials: S
authors.lastname: Ali
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
authors.forename: Nida
authors.initials: N
authors.lastname: Fatima
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan; Chinese Academy of Science (CAS)-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China.
authors.forename: Balal
authors.initials: B
authors.lastname: Yousaf
authors.affiliation: Soil Science Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan.
authors.forename: Asif
authors.initials: A
authors.lastname: Naeem
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Sabir
authors.affiliation: Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
authors.forename: Hamaad Raza
authors.initials: HR
authors.lastname: Ahmad
authors.affiliation: Korea Biochar Research Centre and Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
mesh_terms: D000818:Animals; D002417:Cattle; D002606:Charcoal / Q000737:chemistry*; D002734:Chlorophyll / Q000378:metabolism; D052918:Environmental Restoration and Remediation / Q000379:methods*; D000072480:Farms; D008372:Manure; D009532:Nickel / Q000032:analysis / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D018517:Plant Roots / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*; D003313:Zea mays / Q000187:drug effects* / Q000502:physiology; D015032:Zinc / Q000032:analysis
chemical_list: D008372:Manure; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002734:Chlorophyll; D002606:Charcoal; D009532:Nickel; D015032:Zinc
keywords: Cereals; Growth; Ni toxicity; Organic amendments; Phytoremediation