EFFECT OF NICKEL CONCENTRATION ON TOMATO PLANT NUTRITION AND DRY-MATTER YIELD

An experiment was conducted to study the effect of nickel (Ni) on the nutrition of tomato plants (Lycopersicon esculentum M. cv. Marmande). Dry matter weights of roots, shoots, and fruit were also studied. Plan ts, receiving 5, 15, and 30 mg Ni L-1, were grown in nutrient solution , and roots, stems plus branches, leaves, and fruit were analyzed at d ifferent developmental stages for essential nutrients. The presence of Ni in nutrient medium affected plant growth, decreasing dramatically dry matter yield compared to control plants. This plant reduction was likely due to the disturbances and imbalances of the different essenti al mineral elements. The general effect was a decrease in the absorpti on and accumulation of these nutrients. The nitrogen (N) content in th e plant increased significantly with increasing Ni treatments, showing a synergetic effect between Ni and N. A positive interaction between Ni and potassium (K) was also found. In this way, high levels of Ni in solution caused an increase in K uptake and, however, a decrease in s odium (Na) absorption (antagonism Na/K). Since Ni is taken up as Ni2+, its absorption in high concentrations decreased significantly the upt ake of other divalent cations, such as Mg2+, Fe2+, Mn2+, Cu2+, and Zn2 +, with manganese (Mn) being the nutrient showing the highest restrict ion in the whole plant (roots and shoots).