Aerial root hydraulic conductivity increases with plant size for the aroid vine Rhodospatha oblongata (Araceae) - Journal of Plant Hydraulics Accéder directement au contenu
Article Dans Une Revue Journal of Plant Hydraulics Année : 2017

Aerial root hydraulic conductivity increases with plant size for the aroid vine Rhodospatha oblongata (Araceae)

Résumé

Rhodospatha oblongata (Araceae) is an aroid vine which reaches maturity at tree canopies. The beginning of its ascension towards the canopy occurs when one of the branches reaches the stem of a host, thenceforward reaching eight to ten meters in height. Throughout this ascendant path, R. oblongata develops two types of aerial roots: anchor roots, which are shorter and adhere to the host, never reaching the soil, and feeder roots, which are longer and also adhere to the host, but connect the vine to the forest soil. The morphological, anatomical and physiological aspects of both root types are herein compared in relation to the efficiency of axial hydraulic conductivity. It is hypothesized that i) the two root types present distinct xylem hydraulic conductivity and ii) hydraulic conductivity of both roots varies with plant size. Root characterization was based on growing R. oblongata individuals divided into five size classes. Thirty specimens with both anchor and feeder roots were analyzed along plant size increase. Both roots gradually increase in number and external diameter as R. oblongata vertically ascends to reach plant canopies. The stele of both roots increases in diameter, as well as their respective xylem vessels that become larger. The increase in these morphological and anatomical parameters has a positive influence on xylem hydraulic conductivity, which also increases along the ascendance of R. oblongata. Comparative measurements show that anchor roots, in general, present smaller morphological and anatomical structures and lower hydraulic conductivity in comparison to feeder roots. Xylem diameter distribution is unimodal for anchor roots, but bimodal for feeder roots. While all feeder roots present a great concentration of vessels around 60 µm in diameter, the second peak occurs at xylem diameter values that increase with plant size. These modifications optimize root water transport, while the vegetative body of R. oblongata increases in size, connecting its leaves at canopies to the soil water with elevated hydraulic efficiency.

Domaines

Botanique
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Dates et versions

hal-01995237 , version 1 (26-01-2019)

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Arinawa L Filartiga, Ricardo Vieira, André Mantovani. Aerial root hydraulic conductivity increases with plant size for the aroid vine Rhodospatha oblongata (Araceae). Journal of Plant Hydraulics, 2017, 4, ⟨10.20870/jph.2017.e006⟩. ⟨hal-01995237⟩
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