Iron accumulation in leaf trichomes and stomata of tomato as an iron reservoir provided by iron-citric acid chelate under limey soil conditions.

Abstract

Iron (Fe) is an important mineral needed for plant growth and development. Calcareous (limey) soils cause decline in Fe availability leading to chlorosis in leaves. The correction of Fe chlorosis can be succeeded by the application organic acids. In the present study, we chelated Fe-citrate complex solution, compared with Fe-EDDHA fertilizer, and evaluated the effects of the Fe-citrate chelates on tomato under limey soil condition. The study was conducted in a controlled greenhouse. "Joker F1" cultivar tomato seedlings were used as the material. The seedlings were planted in the 4-L pots filled with mild calcareous soil (pH = 8, CaCO₃ = 10%). All applications, including Fe-citric acid complex, were applied to the roots of the plants (rhizosphere region) as irrigation water, starting with the planting of seedlings and once a week for 2 months. End of the study, many morphological and histological responses were evaluated. Fe accumulation in leaf, trichomes, and stomata was assessed as a Fe pool. Both glandular and non-glandular trichomes were visualized by SEM and light microscopes. Fe was accumulated in trichomes and stomata in Fe-citrate chelates and Fe-EDDHA-applied plants. Leaf cortical cell expansion was significantly increased by iron-citric acid chelates. Fe-citric acid chelates and Fe-EDDHA treatments improved plant growth. The experiment demonstrates that Fe accumulation in trichomes and stomata plays an important role in Fe distribution to leaves as a reservoir under Fe deficiency conditions.