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

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^sup -1^) over control (6.79 mg kg^sup -1^). The foliar application ofFe (3% FeSO^sub 4^.7H^sub 2^O 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 FeSO^sub 4^.7H^sub 2^O kg^sup -1^). Among the soils, acid soil (without lime) produced highest yield (27.4 g pot^sup -1^) of aerobic rice followed by alkaline (21.2 g pot^sup -1^), calcareous (20.0 g pot^sup -1^) and lime-treated acid soils (17.7 g pot^sup -1^). Pusa Sugandh-3 (23.4 g pot^sup -1^) performed better under aerobic condition compared to IR-64 (19.7 g pot^sup -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 Fe^sup 2+^ content of > 42 mg kg^sup -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.