Effects of Flooding and Drought on the Anatomy of Paspalum dilatatum

Abstract

Paspalum dilatatum occupies dierent topographic positions in the Flooding Pampa, Argentina. Populations from dierent positions are subjected to various regimes of¯ooding and drought, both of which may occur in the same growing season. We investigated the constitutive and plastic anatomical traits of P. dilatatum populations from habitats with contrasting regimes of¯ooding and drought. Both events aected root and sheath anatomy, and these eects were similar for clones from dierent topographic positions. Flooding increased the aerenchymatous tissue in the root cortex and the leaf sheaths and decreased the number of root hairs per unit of root length. Drought decreased the diameter of root metaxylem vessels, thus lowering the risk of embolisms and increasing water-¯ow resistance, and increased the number of root hairs, thereby increasing water uptake ability. In addition to these plastic responses, all clones showed constitutive characteristics that may confer an ability to withstand sudden events of¯ooding or drought: a high proportion of aerenchyma, which may maintain aeration before plastic responses take place; sclerenchyma, which may prevent root and leaf sheath collapse by soil compaction; and a conspicuous endodermis, which may protect stelar tissues from desiccation. Both constitutive and plastic anatomical characteristics are likely to contribute to the ability of this species to occupy widely dierent topographic positions and to resist temporal variations in water and oxygen availability.

Leaf plasticity in successive selection cycles of 'Saracura' maize in response to periodic soil flooding

“…When the species have higher quantity of vessels, there is a higher water flow and higher chances to avoid cavitation (Zimmermann, 1983). The diameter of metaxylem vessels is also an important factor in the water flow, because vessels with greater caliber are more prone to cavitation than vessels with smaller caliber (Vasellati et al, 2001). Therefore, the increase in the number of bundles and metaxylem vessels in the last selection cycles of 'Saracura' maize could be protecting the water system and possibly favoring the water absorption in the root, the flow and the distribution of water in the leaves.…”

“…Comparatively, evidences of leaf plasticity are more known in completely flooded plants. Physiological as well as anatomical alterations have been observed in those plants, which are also known as amphibious plants (Voesenek et al, 2006;Mommer et al, 2007).…”

Morpho-Anatomical Changes in Roots of Chickpea (Cicer arietinum L.) under Drought Stress Condition

“…Drought decreased the diameter of the metaxylem bundle in Paspalum dilatatum and caused a reduction in the cortex to central cylinder ratio [39].…”

Preliminary study on the influence of water level on the growth and morphology ofLimnocharis flava(L.) Buchenau

“…In addition, variations in parameters such as specific leaf area, relative water content (RWC) and the chlorophyll content in the tissues have been observed by different researchers (Hussner and Meyer, 2009;Li et al, 2011;Richards et al, 2011). Exposure to prolonged dry periods also affects the plant growth, morphology and development (Vasellati et al, 2001). Changing biomass partitioning patterns to increase root-shoot ratio (Asch et al, 2005), changes in the reproduction system (Rodiyati et al, 2005) and extension of roots toward the deeper soil (Dawson, 1993) or laterally (Wan et al, 1996) are some of the strategies encountered in emergent species when exposed to drought.…”