The elongation rate at the base of a maize leaf shows an invariant patternduring both the steady-state elongation and the establishment of the elongation zone

Spatial and temporal analyses of elongation and cell length of monocotyledo n leaves have most often been performed during the period when leaves are v isible and elongate at a constant rate (steady-state), In the present study , the focus was on the earlier stages, during the establishment of the elon gation zone. Regardless of leaf development stage, the segment located betw een 0 and 35 mm from the leaf insertion point had a relative elongation rat e that increased with distance from insertion point ('accelerating zone') w hile the segment located further than 35 mm had a relative elongation rate that decreased ('decelerating zone'), This stable pattern held for both you ng, non-emerged leaves, where it was restricted to the portion correspondin g to the length of the blade, and for leaves during steady-state elongation . In the same way, the profile of cell length was essentially the same duri ng early development and during steady-state elongation. The results of a t emporal analysis of whole-leaf elongation rate, carried out in the field an d in the greenhouse at different light intensities were consistent with a t ime-invariant pattern of elongation. Whole-leaf relative elongation rate in creased with time until the leaf reached 30-40 mm length (although at diffe rent leaf ages depending on conditions), and declined afterwards. These res ults suggest that the patterns governing the elongation rate of a sector of a maize leaf are independent of the leaf developmental stage but depend on sector position only.