Green leaf area at the silking stage across differing nitrogen regimes.

The error bars represent the standard errors of the mean. Different letters above the bars indicate significant differences (p < 0.05) among different N regimes. N1: 100% N applied as basal fertilizer, N2: 70% N applied as basal fertilizer and 30% N applied at the jointing stage, N3: 50% N applied as basal fertilizer and 50% N applied at the jointing stage, N4: 30% N applied as basal fertilizer, 50% N applied at the jointing stage and 20% N applied at the big flare stage.