Studies on nutrition of rice cultivars under simulated acidic conditions with particular reference to iron

Wide range of critical concentrations reported in literature for iron toxicity makes it questionable as to whether Fe itself is toxic to rice (Oryza sativa L) or is it an indicator of other latent physiological processes that inhibit rice growth. The objective of this greenhouse study was to assess the influence of iron toxicity on tolerance, relative growth, nutritional behaviour (uptake of N, P, K, Ca, Mg, Fe, Mn) and yield of rice cultivars. Sand culture studies using Hoagland-II solution superimposed with varying concentrations of FeSO4 as source of iron resulted in a mild to severe bronzing symptoms on leaves at Fe levels of 250 to 500 ppm. Mahsuri showed no symptoms while Intan Gouri exhibited severe bronzing. The increase in Fe content was positively associated with the Mn content of tissue which was significant in Mahsuri. The involvement of Mn in oxidation of Fe might be one of the reasons for differential tolerance among rice cultivars to iron toxicity.