The development of the shoot apex of Agropyron repens (L.) Beauv
1974
Rogan, P.G. | Smith, D.L.
During the phase of growth between the production of one and 10 mature leaves the primary shoot apex of Agropyron repens undergoes first an increase and then a decrease in size. The apical dome was found to attain a maximum size at the six leaf stage. The changes are attributable to changes in cell number, mean cell size remaining constant after an initial decrease. The zonation pattern, and particularly the number of tunica layers, varies with the size of the dome. The apex as a whole undergoes a greater increase in height than in diameter, with commensurate changes in the number of leaf primordia present upon it. Similar changes occur in the tiller but no such obvious trends were found in the rhizome. In an experiment in which all axillary buds were excised from the primary shoot it was found that the apex continued to increase in size well beyond the maximum attained by that of an intact plant. On this evidence it is suggested that the eventual decline of the primary shoot and tiller apices is due to an inhibitory effect on the main shoot by the developing axillary shoots.
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