Taro response to different iron levels in hydroponic solution¹

Journal Series No. 4116, Hawaii Institute of Tropical Agriculture and Human Resources, University of Hawaii, Honolulu, HI.

Abstract

Iron (Fe) deficiency is a nutritional problem limiting crop production worldwide. To determine the response of taro [Colocasia esculenta (L.) Schott cv. Bun Long] to Fe deficiency, taro propagules were grown for 35 days in hydroponic solutions with six initial levels of Fe (0, 1.25, 2.5, 5, 10, and 20 μM). Taro plants grown in the 0 μM Fe level solution exhibited severe chlorosis of the leaf blades and abnormal root morphology characterized by reduced lateral root formation. Dry weights of leaf blades, roots, and petioles, total biomass, and leaf area were significantly lower in the 0 μM Fe treatment than in the other treatments. However, there were no significant differences in these parameters among treatments in the range of 1.25 to 20 μM Fe. Segmented regression models best described both the effect of initial Fe levels on leaf blade Fe content (R²=0.98), and the relationship between leaf blade dry weight and leaf blade Fe content (R²=0.92). The critical Fe level in leaf blades is probably not a fixed point but rather a range between 55 to 70 mg Fe/kg (dry weight basis). No significant interactions were observed between Fe concentrations in the leaf blades and other nutrients.

Notes

Journal Series No. 4116, Hawaii Institute of Tropical Agriculture and Human Resources, University of Hawaii, Honolulu, HI.

University of Hawaii, Hawaii Branch Station, 461 West Lanikaula Street, Hilo, HI 96720.