The Effect of Zinc and Iron Applications from Different Sources to Growth, Dry Matter, and Its Uptake by Lettuce (Lactuca sativa)

Zinc (Zn) and iron (Fe) are among the micronutrients humans need. However, the main food sources in developing countries such as Malaysia have low micronutrients, making it insufficient to supply the minimum daily requirement. Foliar fertilization is one of the most effective and safe ways to enrich important micronutrients in plants. This study investigated variations in Zn and Fe sources to evaluate the effects of individual Zn and Fe foliar applications on growth, dry matter, and nutrient uptake by lettuce (Lactuca sativa). Based on the result, the application of Zn and Fe in the form of sulfate salt showed a lower toxicity effect in terms of growth and dry matter of plants than Fe and Zn in the form of ethylenediaminetetraacetic acid (EDTA). In terms of Zn uptake, it was found that there was a significant difference observed compared to the control, especially when 3 kg/ha Zn was applied, regardless of whether it was in the form of sulfate or EDTA. Furthermore, there was an increase in Fe uptake observed with increased Zn application. In contrast, the Fe application showed no difference in Fe intake compared to the control. It was found that there is a decrease in Zn uptake observed with increasing application of Fe rate. Sufficient Fe content is already available in the soil, and plants only take up what is needed for growth.