Differential response of foliage plants to iron deficiency

Eight species of tropical foliage plants were screened to determine their response to Fe‐stress conditions. Plants were grown for 120 days in modified Hoagland's nutrient solution at pH 6.3 containing either 0, 0.22 or 5.52 mg/liter Fe (as Fe⁺³‐HEEDTA). Araucaria heterophylla and Dracaena marginata showed leaf chlorosis and decreased growth at 0 and 0.22 mg/liter Fe. Ficus benjamina and Nephrolepis exaltata ’Bostoniensis’ showed little or no chlorosis or growth differences at either 0 or 0.22 mg/liter Fe. Over a 3 week period, F. benjamina and N. exaltata ’Bostoniensis’ decreased nutrient solution pH approximately 1 to 1.5 units lower than either D. marginata or A. heterophylla at all Fe levels. Codiaeum variegatum var. pictum, Dieffenbachia maculata ’Camille’, Epipremnum aureum, and Philodendron scandens oxycardium were intermediate in growth, chlorosis and lowering of the nutrient solution pH. One explanation for the differential Fe response between these species may be their ability to lower pH of the rhizosphere.