IRON AND NITROGEN INTERACTIONS IN GROUNDNUT NUTRITION

A pot experiment was conducted to estimate the levels of iron (Fe) nee ded to correct Fe-deficiency chlorosis in groundnut grown in an alkali ne soil and to study Fe x nitrogen (N) interactions in soil and plant and their associated effects on growth and yield. Four levels of Fe (0 , 2.5, 10, and 25 mg Fe kg(-1) soil as Fe-EDDHA) and two levels of N ( 0 and 100 mg N kg(-1) soil as NH4NO3) were applied factorially in a co mpletely randomized block design. Higher rates of 10 and 25 mg Fe kg(- 1) caused a significant reduction in leaf area and aerial biomass accu mulation irrespective of N treatment. The Fe x N interaction was signi ficant for all of these parameters. Specific leaf area increased at hi gher levels of Fe application. Higher Fe levels induced symptoms sugge stive of manganese (Mn) deficiency. This diagnosis was supported by de creasing concentration of Mn in leaf blades with increasing Fe levels. By contrast concentrations of most other elements in leaf blades incr eased with increasing levels of Fe application, suggestive of plant gr owth but not uptake of other elements being reduced by Mn deficiency.