Growth and physiological responses of three poplar clones grown on soils artificially contaminated with heavy metals, diesel fuel, and herbicides

We tested the growth and physiological responses of three poplar clones [Populus deltoides Bartr. ex Marsh. ‘Bora’, ‘PE 19/66’; Populus × euramericana (Dode) Guinier ‘Pannonia’] grown for 3 years on soils artificially contaminated with heavy metals, diesel fuel, and herbicides at the Experimental Estate of the Institute of Lowland Forestry and Environment (ILFE), University of Novi Sad, Serbia. Within three field blocks, clonal whole-plots were divided into seven subplots containing a non-contaminated control and six artificially-contaminated soil treatments: (1) 10.6 kg Cd ha⁻¹, (2) 247 kg Cu ha⁻¹, (3) 183.3 kg Ni ha⁻¹, (4) 6,667 L diesel fuel ha⁻¹, (5) 236 g Oxyfluorfen ha⁻¹, and (6) 1,320 g Pendimethalin ha⁻¹. Significant clone × treatment interactions governed growth and physiology throughout the study (p < 0.05), and the influence of inorganics versus organics varied with tree age. Heavy metals had a more substantial influence on growth and physiology as the trees matured, while diesel and herbicide treatments were most pronounced during the first growing season (p < 0.0001). Clones ‘Bora’ and ‘PE 19/66’ exhibited greater biomass than ‘Pannonia’, with trees growing in the control soils exhibiting 13.8 and 19.6 times greater biomass than ‘Pannonia’, respectively.