Comparison of chlorophyll content in greenhouse tomato and cucumber leaves after HBED-Fe and EDDHA-Fe applications

ABSTRACT Iron is an essential micro-element for plant growth. In the calcareous soils of Lebanon, immobilization of iron can lead to chlorosis and reduce the yields of agricultural production. Iron fertilization is therefore crucial to ensure good plant growth. The objective of this work was to compare the efficiency of the iron chelate HBED-Fe to that of EDDHA-Fe, on tomato (Solanum lycopersicum L.) and cucumber crops (Cucumis sativus L.). Five modules were studied in two separate greenhouses: one control, one module with fertilization by EDDHA-Fe and three modules with different applications of HBED-Fe. Chlorophyll and Fe contents in leaves were analyzed at different stages of the plants' cycle. Cucumber crops treated with HBED-Fe showed 19.2% higher chlorophyll content than the ones treated with EDDHA-Fe. Tomato crops presented 11.2% higher chlorophyll content when treated with HBED-Fe. For cucumbers, HBED-Fe should be applied in three applications separated by 25 days. For tomatoes, HBED-Fe should be applied in two applications separated by a month. The use of the HBED9% iron chelate was proved to be more effective than that of EDDHA6% because more efficiency was achieved with 40% less application rate. Multiple applications were also more effective than single applications.