FIGURE 7.

Principal component analysis (PCA) of all parameters for treatment combination of TU and BC. T₀ = 0 mg L^–1; T₁ = 600 mg L^–1; T₂ = 600 mg L^–1; B₀ = 0% w/w; B₁ = 2.5% w/w; B₂ = 5.0% w/w. BC, biochar; TU, thiourea; RL, total root length; RFB, root fresh biomass; RDB, root dry biomass; SL, shoot length; SFB, shoot fresh biomass; SDB, shoot dry biomass; LAI, leaf area index; SOD, superoxide dismutase in leaves; POD, peroxidase in leaves; CAT, catalase in leaves; EL, electrolyte leakage in leaves; MDA, malondialdehyde; H₂O₂, hydrogen peroxide; Ci, intercellular CO₂ concentration; Pn, net photosynthesis rate; Gs, stomatal conductance; Tr, transpiration rate; SPAD, SPAD value; Soil Cd, cadmium concentration in soil; Shoot Cd, cadmium concentration in maize shoot; Root Cd, cadmium concentration in root.