Effect of iron application on iron nutrition of aerobic rice grown in different soils

Abstract

Enhancing the content of Fe in edible portion of rice for improving human health is a global challenge. A greenhouse experiment was conducted to evaluate the relative effectiveness of soil, foliar and seed treatment of Fe in alleviating Fe-deficiency using two rice cultivars (IR-64 and Pusa Sugandh-3) grown on alkaline, calcareous, acid and lime-treated acid soils. Results showed that on an average, soil application of Fe improved the available Fe status of soil (8.14 mg kg⁻¹ ) over control (6.79 mg kg⁻¹ ). The foliar application of Fe (3% FeSO4.7H2O solution, thrice 40, 60 and 75 days after sowing of rice) was more effective and economical in enhancing the yield (9.42%) as well as increasing Fe content (3.48%) of milled rice as compared to soil application (67 mg FeSO4.7H2O kg⁻¹ ). Among the soils, acid soil (without lime) produced highest yield (27.4 g pot⁻¹) of aerobic rice followed by alkaline (21.2 g pot⁻¹ ), calcareous (20.0 g pot⁻¹ ) and lime-treated acid soils (17.7 g pot⁻¹ ). Pusa Sugandh-3 (23.4 g pot⁻¹ ) performed better under aerobic condition compared to IR-64 (19.7 g pot⁻¹ ). Ferrous-iron content in rice plants proved to be a better index of Fe nutrition status compared to total plant Fe and chemically extractable soil Fe. The Fe²⁺ content of ≥ 42 mg kg⁻¹ in plants (on dry weight basis) appeared to be an adequate level at 45 days after sowing for rice grown under upland aerobic condition.