The Effects of Plant Density on Shoot and Leaf Lamina Angles in Lolium multiflorum and Paspalum dilatatum
1992
Gibson, D. | Casal, J.J. | Deregibus, V.A.
The effects of plant density on shoot and leaf lamina zenith angles (i.e. the angles with respect to the vertical) were investigated in Lolium multiflorum and Paspalum dilatatum plants grown in pots either outdoors or in a glasshouse. Tillers appeared above the ligule of their subtending leaf with a small zenith angle but, in plants grown at low densities, gradually adopted a more horizontal position. In plants grown at high densities this gradual increase in shoot zenith angle with age was strongly reduced. The average shoot zenith angle at a given time was lower (i.e. tillers were more erect) at high, compared to low plant densities. Shoot number per plant and average shoot zenith angle per plant were directly related. In P. dilatatum plants the leaf lamina remained nearly horizontal at any plant density. This observation indicates that the movement of the leaf lamina, pivoting at the point of attachment to the leaf sheath, compensated the movement of the shoot, pivoting at the base of the leaf sheath-tube. Shoot angle responses to plant density would place leaf laminae at different heights within the canopy, affecting their ability to compete for light and their susceptibility to wind impact and herbivore grazing.
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