Influence of Organic Amendments on Growth and Lead Uptake of Spinach (Spinacia oleracea L.) Grown in Lead-Contaminated Soil Abdur Rashid 1,2* , Tayyaba Naz 1 , Muhammad Mazhar Iqbal 1,3 , Javed Akhtar 1 , Muhammad Saqib 1 , Hafiz Muhammad Anwar-ul-Haq 1 , Rooh Ullah 2 , Salahudin Kabir 4 , Qiyamud Din Ikram 5 1 Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Punjab 38000, Pakistan 2 Ministry of Rural Rehabilitation and Development, Kabul, Afghanistan 3 Soil and Water Testing laboratory Chiniot, Department of Agriculture, Government of Punjab, Lahore, Pakistan 4 Institut Supérieur d'Agriculture de Lille, Lille 59800, France 5 United Nation University, Institute for Environment and Human Security Bonn, Bonn 53113, Germany Corresponding Author Email: abdurrashiduaf@gmail.com https://doi.org/10.18280/eesrj.070201 ABSTRACT Received: 19 February 2020 Accepted: 13 May 2020 Lead (Pb) is a very serious contaminant in soil because of its widespread application in agricultural, residential and industrial environments and it has ultimately harmful impacts on plant and human health. Organic amendments such as biochar (BC) and compost may reduce heavy metal toxicity in a plant. The main focus of the present research work was to evaluate the synergistic use of BC and compost to enhance the growth of spinach and to reduce the Pb uptake in spinach (Spinach oleracea L.) grown on Pb-contaminated soil. The results showed that Pb toxicity at its higher-level (1000 mg Pb kg-1 soil) reduced the growth, photosynthetic pigments and physiological attributes in 45-days-old spinach. However, this decrease was less pronounced in BC and compost amended soil. The BC and compost application enhanced shoot dry weight, total chlorophyll contents, membrane stability index and relative water contents at both applied rates 500 and 1000 mg kg-1 of Pb in soil. Under low Pb-stress (500 mg Pb kg-1), BC and compost application increased the shoot dry weight (33.5 and 39.7%), chlorophyll contents (21 and 22.1%), membrane stability index (18.8 and 17%) and relative water contents (44 and 34.6%). While at high Pb-stress (1000 mg kg-1) BC and compost increased the shoot dry biomass (17.8 and 33.3%), chlorophyll contents (31.3 and 32.5%), membrane stability (27.1 and 23.5%) and relative water contents (37 and 32.9%) respectively. Moreover, under low Pb stress the application of BC and compost reduced the Pb uptake in spinach by 78 and 56%. While under high Pb stress, BC and compost reduced the Pb uptake by 69 and 52% respectively. Therefore, it can be concluded that organic amendments can ameliorate Pb- toxic effects in spinach by changing the physiological attributes (total chlorophyll content, MSI and RWC) under Pb stress. Among the tested amendments, applied BC proved more effective for reducing Pb toxicity in spinach. Keywords: biochar, compost, heavy metal pollution, immobilization, Spinacia oleracea L 1. INTRODUCTION Heavy metal pollution of soil is a threatening issue around the globe. It is not only responsible to affect the quality and yield of crops, human and animal health but also the environment [1]. The major sources of heavy metal pollution in soil can be find in sewage sludge, industrial waste, mining, excessive pesticides and chemical fertilizers use and smelting of ores [2]. These sources have caused a recent gradual increase in heavy metal concentration and are swept over the self-purification ability of nature [3]. Subsequently, these heavy metals persist for a long period, which can be up-taken by plants to accumulate in plant tissues and hence enter to food chain [4]. These trace elements are entering to living bodies via different means like air, food, water and skin contact. Major health problems linked with heavy metals are mild cognitive impairment (MCI), chronic anemia and cardiovascular diseases [5], damage of nervous system, kidney, brain [6], bones, teeth, skin [7]). Some of these trace elements are carcinogenic, endocrine disruptors, teratogenic and mutagenic whereas, others can cause behavioral and neurological disorders especially in children [8]. These trace elements at a high concentration are obstructing both growths of underground and above surface parts of plants which can cause to inhibit the development and growth of plants and also to disturb many physiological and biochemical activities e.g. reduction in transpiration rate, damage the photosynthetic apparatus, cause breakdown synthesis, injury of the cell membrane, increase lipid peroxidation and also affect several enzymes [9]. Among heavy metals, Pb is considering one of the most hazardous toxic elements and thus it is biologically non- essential in nature. Lead occurs extensively in the environment due to its wide spread applications in petrol, paints, explosive materials, industrial wastes, and sludge. Uptake and translocation of Pb occur in plants which causes toxic impacts on its health and ultimately a declination occurs in the plant biomass production. Usually, plant avoids its toxic effects by adopting different cellular mechanisms such as adsorption to the cell wall, vacuole compartmentalization, increase the Environmental and Earth Sciences Research Journal Vol. 7, No. 2, June, 2020, pp. 53-61 Journal homepage: http://iieta.org/journals/eesrj 53