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Ontogenic variation and effect of collection procedure on leaf biomechanical properties of Mediterranean seagrass Posidonia oceanica (L.) Delile
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Orientador(es)
Resumo(s)
Leaf mechanical traits are important to understand how aquatic plants fracture
and deform when subjected to abiotic (currents or waves) or biotic (herbivory
attack) mechanical forces. The likely occurrence of variation during leaf ontogeny in these traits may thus have implications for hydrodynamic performance
and vulnerability to herbivory damage, and may be associated with changes in
morphologic and chemical traits. Seagrasses, marine flowering plants, consist of
shoot bundles holding several leaves with different developmental stages, in
which outer older leaves protect inner younger leaves. In this study we examined
the long-lived seagrass Posidonia oceanica to determine ontogenic variation in
mechanical traits across leaf position within a shoot, representing different developmental stages. Moreover, we investigated whether or not the collection procedure (classical uprooted shoot versus non-destructive shoot method: cutting the
shoot without a portion of rhizome) and time span after collection influence
mechanical measurements. Neither collection procedure nor time elapsed within
48 h of collection affected measurements of leaf biomechanical traits when seagrass shoots were kept moist in dark cool conditions. Ontogenic variation in
mechanical traits in P. oceanica leaves over intermediate and adult developmental stages was observed: leaves weakened and lost stiffness with aging, while midaged leaves (the longest and thickest ones) were able to withstand higher breaking forces. In addition, younger leaves had higher nitrogen content and lower
fiber content than older leaves. The observed patterns may explain fine-scale
within-shoot ecological processes of leaves at different developmental stages,
such as leaf shedding and herbivory consumption in P. oceanica.
Descrição
Palavras-chave
Biomechanics; leaf age Non-destructive shoot method Plant ontogeny Seagrass Stiffness Strength
Contexto Educativo
Citação
Editora
Blackwell Verlag GmbH