Concentration (content per unit plant dry weight) of macro and micronutrients were significantly influenced by plant age, except manganese and copper (Figures 3 and 4). Concentration of N, P, and K decreased during the reproductive growth stage. However, Ca and Mg concentration were increased in a quadratic fashion during advancement of plant age. The micronutrients Fe and Zn also decreased during reproductive and grain filling growth stage. The decrease in concentration of some macro and micronutrients may be associated with increase in dry weight of shoot with the advancement of plant age. This effect in mineral nutrition is known as dilution effect (Fageria et al., 1997). Uptake of macro and micronutrients were significantly increased in a quadratic fashion with the advancement of plant age (Figures 5 and 6). This increase in uptake of these nutrients may
be associated with the increase in shoot dry weight with the advancement of
plant age.