Influence of Copper Chelation by EDTA on Growth, Survival and Development of Plumed Cockscomb (Celosia argentea) Cultivar (TVL 8) in Clay, Loamy, Sandy Garden Top and Red Earth Soils

Abstract

A greenhouse experiment was conducted to investigate the impact of chelation of Copper (Cu) toxicity on growth, survival and development by growing plumed cockscomb (Celosia argentea) cultivar (TLV 8) in 4 kg each of clay, loamy, sandy, garden topsoil and red earth contaminated with 500 mgL^-1. Cu and 5M Methylene diaminetetaacetic acid (EDTA) in the following combinations: 500 mg Cu L^-1 as CuSO₄·5H₂O and 500 mgL^-1 Cu + 5M EDTA with a control (absence of Cu and EDTA). This application was performed two weeks after planting (WAP) and was repeated at 6 WAP. Variations were observed in soil pH and organic matter content. Using the American soil texture triangle five soil types had the following soil textures: sandy-clay-loam (clay soil), sandy (garden-top soil), sandy (sandy soil), loamy-sandy (loamy soil) and sandy-loamy (red-earth). In the course of ten weeks of growth, growth parameters and morphometric characteristics were determined. Cu toxicity caused a significant reduction in growth parameters (plant height, dry root weight, dry stem weight, leaf area, leaf area ratio, and absolute growth rate) in all soil types but the maximum reduction was observed in sandy soil while the highest growth exhibited by plants grown in a loamy soil. Increasing soil copper concentration by a second applications (2 and 6 WAP) reduced the number of leaves (37% - 56%) and plant height (10% - 21%) in all soil types. Presence of EDTA in the medium effectively alleviates growth reduction induced by Cu toxicity in plants by increasing the physiological growth parameters of Celosia argentea. The performance of plant grown in the various toxic soil sample appeared to be inhibited by copper in the following order: Cu > Cu + EDTA > Control. Furthermore, loamy soil stimulated better growth of Celosia in a Cu-toxic environment.