Effect of Various Environments on the Anatomy and Growth of Perennial Ryegrass and Cocksfoot

Summary Plants of Lolium perenne and Dactylis glomerata were grown in combinations of 100, 80, and 20% of full daylight, and mean day temperatures of 10.6, 15.2, and 20.5°c. Half the plants of each species were defoliated at transfer to experimental conditions. At harvest, the upper portion of the main tiller with attached leaf bases was fixed and sectioned longitudinally. Apical meristem diameters were measured at all leaf insertions from the apex to that of the youngest mature leaf. Defoliation reduced diameters of the apical column and sub‐apical region and also reduced the height of the apical column and the number of leaf pri‐mordia on it. The apex diameter was unaffected. Differences in light intensity or temperature had a minor and variable effect on the quantities measured. Differences in diameter at leaf insertions at the base of the column and at the top of the sub‐apical region appeared to be a consequence of differences in cell number. It was concluded that the size of the sub‐apical region per se had comparatively little influence on the size of leaves or the rate of leaf formation on the main tiller.