Effect of copper and zinc on seed germination, phytotoxicity, tolerance and seedling vigor of tomato (Lycopersicon esculentum L. cultivar Roma VF)

Abstract

To investigate the effect of copper and zinc on germination, phytotoxicity, seedling vigor and tolerance, a laboratory experiment was undertaken on tomato (cultivar Roma VF) at Ambo University, Ethiopia. Copper and zinc in seven levels each (0, 100, 200, 300, 400, 500 and 600 ppm), were arranged in factorial CRD with four replications. Copper and zinc concentrations significantly (p<0.05) decreased germination percentage and rate, shoot and root lengths, seedling vigor, and tolerance. However, toxicity percentage to shoot and root increased significantly (p<0.05) with increasing metals concentrations. Maximum germination, shoot and root lengths, tolerance, and seedling vigor were obtained with controls. Minimum value for the germination percentage (76.6%), germination rate (4.6plants/day), shoot and root lengths, tolerance and vigor were expressed at 600ppm - zinc; however, copper ≥300ppm induced total failure on tomato seeds germination. The highest toxicity to shoot (92.3%) and root (93.4%) appeared at 600ppm zinc, whereas ≥300 ppm copper caused 100% toxicity on shoot and root. 100ppm, copper was toxic to shoot (61%) and roots (85%), while zinc showed toxicity of 68% of shoot and 66% of root toxicity. Hence, other than 100ppm, copper is more toxic than zinc for germination and seedling growth of Roma VF.