Conflicting reports exist about the effect of N supply on the rate of leaf emergence. We examined effects of N deficiency on leaf and tiller emergence, tiller initiation and apical development in 'Aroona' and 'Gamenya' spring wheat (Triticum aestivum L.). Four levels of N (e.g., 50 micrometer N = N50) were supplied by hourly irrigation with complete nutrient solution of plants growing in sand. The control plants in Exp. 1 (N1600) had 64 g kg to the -1 N in the shoots at the two-leaf stage, compared with 33 in N50, 50 in N300, and 58 in N800. Compared with control plants, dry matter of N50 plants was 10%, N300 50%, and N800 80%. Results in Exp. 2 were similar. The rate of leaf emergence was decreased in all N50-treated and some N200-treated plants, but not N300- or N800-treated plants. Tiller bud initiation was decreased in the N50 treatment. The number of tiller buds was correlated with total number of leaves; if a leaf emerged, N deficiency did not affect tiller initiation. Nitrogen treatment did not alter the sequence of tiller emergence, but tiller emergence was delayed or did not occur in N50, N200, and N300 plants. Nitrogen treatment had little effect on the rate of apical development. The double-ridge stage of development was delayed approximately equal to 2 d for both cultivars at the two lowest N treatments. Terminal spikelet production was also delayed by approximately equal to 2 d at these N treatments in Aroona, but not in Gamenya spring wheat. The rate of primordia initiation was decreased in N50 and N300 plants, resulting in fewer spikelet primordia. The level of N deficiency affected plant response to the stress.