Synthesis of Copper-Chelates Derived from Amino Acids and Evaluation of Their Efficacy as Copper Source and Growth Stimulator for <i>Lactuca sativa</i> in Nutrient Solution Culture

Abstract

Five tetradentate ligands were synthesized from l -amino acids and utilized for the synthesis of Cu(II)-chelates 1 – 5 . The efficacy of Cu(II)-chelates as copper (Cu) source and growth stimulator in hydroponic cultivation was evaluated with Lactuca sativa . Their stability test was performed at pH 4–10. The results suggested that Cu(II)-chelate 3 is the most pH tolerant complex. Levels of Cu, Zn, and Fe accumulated in plants supplied with Cu(II)-chelates were compared with those supplied with CuSO 4 at the same Cu concentration of 8.0 μM. The results showed that Cu(II)-chelate 3 significantly enhanced Cu, Zn, and Fe content in shoot by 35, 15, and 48%, respectively. Application of Cu(II)-chelate 3 also improved plant dry matter yield by 54%. According to the results, Cu(II)-chelate 3 demonstrated the highest stimulating effect on plant growth and plant mineral accumulation so that it can be used as an alternative to CuSO 4 for supplying Cu in nutrient solutions and enhancing the plant growth.