It has been proposed that glutathione can relieve the effects of Fe deficiency. This study tested the effects of glutathione foliar treatments to prevent Fe chlorosis, using as positive controls soil and foliar Fe fertilisation.Medicago scutellataplants were grown in soil -5.7% CaCO 3 - supplemented or not with 4 and 8% CaCO3 . Two Fe-III--EDDHA soil treatments -5 and 10 mg Fe kg –1 -, and three foliar treatments -three applications each of 2.14 mM Fe-III--EDDHA, 1 mM glutathione, and the previous two combined- were applied. Measurements include leaf chlorophyll and Fe concentrations, biomass, leaf enzymatic and non-enzymatic antioxidant systems and carboxylates. The addition of CaCO 3 caused typical Fe deficiency symptoms, including changes in chlorophyll, Fe, antioxidant systems and carboxylates, which were prevented by soil and foliar Fe fertilisation. The foliar treatment with glutathione also led to higher chlorophyll, leaf extractable Fe and root Fe, as well as decreases in some antioxidant systems, whereas leaf Fe concentrations decreased. The combined foliar application of glutathione and Fe was even more efficient in preventing chlorosis. Including glutathione in foliar fertilisation programs should be considered as an option for Fe chlorosis prevention, especially when relatively large leaf total Fe concentrations occur in the so called chlorosis paradox.

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