This study tests the hypothesis that silica accumulation in grasses is an inducible response to grazing. It also examines if silica concentration is correlated to other leaf structural and chemical parameters. To that end, five tropical grass species (Andropogon gayanus var.
bisquamulatus, Elymandra androphila, Hyparrhenia subplumosa, Panicum maximum var. C1 and Panicum maximum var. local) were subjected to various clipping treatments in cultivation. Clipping was found to increase silica concentration in three of five species (blades and sheaths),
but this response was rarely strong and varied with clipping frequency. Defoliation also caused other changes in leaf structure, i.e. production of leaves with juvenile characters including higher Specific Leaf Area (SLA), higher Relative Water Content (RWC), and lower carbon concentration.
This suggests that enhanced silica accumulation is not a very specific response to defoliation. Silica concentration also varied among species and was correlated to leaf structure and chemical composition. Andropogon gayanus var. bisquamulatus had the lowest silica concentration
and the highest carbon concentration, while Panicum maximum showed the opposite combination of traits, suggesting that species with more sclerified leaves might be less silicified. Positive correlations between silica content and RWC, soluble ash, and SLA suggest that variation in silica
accumulation among species and treatments might be related to transpiration rate.
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