Effect of toxic iron concentrations on the growth of lowland rice

Iron (Fe) toxicity is a complex and major nutritional soil constraint affec ting rice production in the irrigated and rainfed lowland soils in various parts of the World including West Africa and Nigeria in particular. Data re lated to the reaction of rice cultivars especially ITA 212 and Suakoko 8 in the West Africa sub-region to Fe concentrations is sparse. A pot experimen t was conducted involving these two rice cultivars, two soil types with pre vious history of Fe-toxicity and four Fe2+ levels (control, 1000, 3000, and 4000-mg Fe2+ L-1). The experiment was a factorial design with the treatmen ts arranged in a completely randomized fashion with three replications. The effects of various Fe-levels were measured on bronzing symptoms, tissue nu trient contents, plant height, tiller numbers/pot, at 30, 60, and 90 days a fter transplanting (DAT) while grain and dry matter yields were measured at harvest. The results clearly showed that with increasing Fe2+ levels, tiss ue phosphorus (P), potassium (K), and manganese (Mn) contents decrease with age and with increasing Fe2+ levels while calcium (Ca), magnesium (Mg), an d Fe contents increase. Increasing Fe2+ levels was also observed to reduce dry matter yields, tiller numbers/pot and plant height significantly (P les s than or equal to0.05).