Heavy metal accumulation in various tissues of radish (Raphanus sativus) grown under different ratios of organic amendments

Root vegetables have greater risk of metal contamination from compost application to soil than other horticultural crops. Moreover, soil organic amendments pose potential environmental hazards. The objective of the present study was to examine the heavy metal uptake in different tissues (petiole, blade, skin, pulp) of Raphanus sativus exposed to organic amendments doses. The impact of the above materials on heavy metal concentration of the soil and plant development parameters were also evaluated. A pot experiment was established with eight treatments arranged in a randomized complete block design and four replicates. Co-compost of sewage sludge and olive wastes at 100, 200, 300 m3 ha–1, composted olive leaves, olive tree pruning wastes, olive mill pomace and poultry manure at 100, 200 m3 ha–1, commercial liquid organic fertilizer at 50 Kg ha–1 with or without inorganic NPK fertilization and a no fertilizing control, were applied to plants. The results showed that sewage sludge application strongly increased the yield and improved radish size cultivated in silt loam soil. The edible radish part had the lowest Fe, Mn, Cu, Zn, and Cr content, whereas the highest Mn, Cu, Zn, Cr was found in the blade and increased Fe, Ni, Pb were recorded in the skin. Organic treatments gave higher Fe, Mn, Cu, Zn amount in both aerial plant tissues compared to the control soil, while Ni, Pb, Cr of all the radish parts were not affected by treatments. This study suggested that organic amendments application gave low permissible levels of all metal content in radish tissues and increased radish productivity. Therefore, organic materials used herein can be applied for normal plant growth without metal contamination of the plant and the soil.