DIFFERENTIAL TRANSLOCATION OF ⁵⁹IRON IN IRON SUFFICIENT AND DEFICIENT SORGHUM PLANTS

Abstract

Radioactively labeled iron (⁵⁹Fe) was used to study differential uptake in sorghum plants in the recovery stage of chlorosis. Radio-labeled ⁵⁹Fe was supplied through root feeding in nutrient solution experiment (48 hrs, pH 6.2) to non-chlorotic and chlorotic plants. Chlorotic plants were further treated with foliar spray [ferrous sulfate (FeSO₄), FeSO₄ + thiourea (TU), FeSO₄ + citric acid (CA), FeSO₄ + thioglycollic acid (TGA)] to study the uptake of radio-labeled ⁵⁹Fe through root feeding during recovery process of chlorosis. Under iron deficiency, the differential uptake of ⁵⁹Fe was markedly increased in leaves and stem of chlorotic control (-Fe) sorghum plants as compared to non-chlorotic control (+Fe) and foliar sprayed (FeSO₄, FeSO₄ + TU, FeSO₄ + CA, and FeSO₄ + TGA) plants. The lowest uptake of ⁵⁹Fe was observed in younger leaves (24.33 nmol, g⁻¹ fresh weight h⁻¹) and stem (1.98 nmol, g⁻¹ fresh weight h⁻¹) of non-chlorotic control followed by foliar sprayed plants in comparison to chlorotic control, respectively. Similarly less ⁵⁹Fe uptake was observed in the older leaves of FeSO₄ + CA sprayed (21.70 nmol, g⁻¹ fresh weight h⁻¹) plants in comparison to chlorotic control (35.60 nmol, g⁻¹ fresh weight h⁻¹). The highest differential ⁵⁹Fe uptake through nutrient medium was in the roots of plants, which were foliar sprayed with FeSO₄ along with TU. The role of iron alone and along with citric acid and thiol compounds is discussed in recovery of chlorosis.

Keywords:

• iron chlorosis
• foliar application
• ferrous sulfate
• citric acid
• thiourea
• thioglycollic acid
• chlorophylls
• active iron
• iron (⁵⁹Fe) uptake
• thiols
• Sorghum bicolor

ACKNOWLEDGMENT

This work has been undertaken with the financial support received from Board of Research in Nuclear Science (BRNS), Department of Atomic Energy (DAE), Mumbai.