RESUMEN
The effect of increasing doses of iron, manganese and zinc applied as soil application on growth and uptake of nitrogen, phosphorus, potassium and magnesium by sunflower and squash plants was studied in pot experiment under greenhouse conditions. The growth of sunflower and squash plants responded positively to soil application of Fe, Mn or Zn. In sunflower plants, zinc application induced the highest effect on uptake of macronutrients compared with iron and manganese application. Whereas, adding iron gave the highest response in squash plants. The ratio of shoot/ root dry weight increased only with iron and zinc in both sunflower and squash plants. The marked increase in content and uptake of N, P, K and Mg by applying Fe, Mn and/or Zn suggests that when plant nutrition was balanced by using micronutrients, plants could make a better use of macronutrients