The crown is comprised of connective tissue which joins the root and shoot. It develops at the base of the coleoptile during seedling development. The crown produces buds that are the source of shoots (tillers), adventitious roots, rhizomes, and stolons. Crowns also serve as storage organs for carbohydrate reserves to support the growth of new plant organs.
During the vegetative stage, when the shoot apex and blade meristems are situated safely below grazing height, there is minimal danger of mismanagement. Nevertheless, avoid severe defoliation during this stage to ensure continued leaf growth and further development of the plant systems.
With sod-forming rhizomatous grasses, if above-ground meristem systems are destroyed, recovery will depend upon new shoot initials arising from adventitous buds in crown tissue. Inspect this zone for the appearance of new shoot initials. If none are present, avoid severe defoliation.
With bunch grasses, preserve leaf blade collars until new shoot initials are evident either in crown tissue at the shoot base, or can be found arising from basal nodes of the culm (as in annual ryegrass). (See Deams, page 24, figure 4)
[Shoot initials can be exposed by stripping the sheath from enclosed internode.] If shoot initials are weakly developed, move the livestock to an adjacent paddock or otherwise reduce stocking rate to prevent destruction of the currently active shoots.
For either sod forming or bunch grasses, "take a half, leave a half" is usually wise advice. This ensures the preservation of the above ground regrowth mechanism until an alternative regrowth mechanism is developed.
Severe defoliation with exposed leaf collars may result in minimal leaf area in recovery growth. The seed head, however, remains in the stubble suppressing the growth of shoot initials from axillary and/or crown buds. This suppression is called apical dominance.