Iron (Fe) deficiency in plants is one of the major nutritional disorders prevalent on calcareous soil, is also termedas lime induced iron chlorosis (LIIC). Such plants however, induce biochemical mechanisms of adaptation. These changesin biochemical mechanisms of groundnut (Arachis hypogaea L.) plants were studied in hydroponically setup experimentcontaining 0, 1, 3 ppm Fe and 3 ppm Fe plus15 ppm lime. It was found that, at 45 days LIIC resistant genotype ICGV86031 recorded highest leaf ferrous content (7.44 ppm), chlorophyll content (2.41 mg g-1 fresh weight), highest root ferricreductase activity (56.86 n mol gm-1 fresh weight 2 hr-1) and highest root protonation (i.e., least pH of 3.83). All these valueswere significantly lower in susceptible genotypes JL 24 and TMV 2. Thus, it is confirmed that strategy I mechanism ofacquiring iron in lime condition was found existing in groundnut. The chlorosis resistant genotype ICGV 86031 has higherroot protonation and higher root ferric reductase activity of strategy I mechanism under lime condition.