Abstract

Patrick Okori, Cosmos Magorokosho and Thokozile Ndlela

The effect of cadmium (Cd) accumulation on mineral composition in roots and shoots, growth development, chlorophyll and water content of tomato (Solanum lycopersicon Mill 63/5F1) seedlings was tested under doses of 0 (control), 10, 50 and 100 µM. Cadmium accumulation was defined by elevated concentrations as 50 to 100 µM in root and shoot tissues. Element uptake by roots and shoot was negatively affected by raise in cadmium concentrations, especially in 100 µM Cd. Root and shoot elongation, root and shoot fresh and dry biomass, leaf area were negatively affected by increasing Cd concentrations. Tissue water content, growth tolerance index, chlorophyll a, chlorophyll b and total chlorophyll content were limited by cadmium toxicity. The addition of Cd in the growth medium also had significant deleterious effect on net photosynthetic rate (Pn) and intracellular CO2 concentration (Ci), with Pn being reduced by 27.2 and 62.1% at 5 μmol/L and 100 µM Cd treatments compared to the control, respectively, while Ci increased correspondingly by 28.4 and 39.3%.