Hydraulic architecture and water flow in growing grass tillers (Festuca arundinacea Schreb.) |
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| Authors: | P Martre H Cochard & J-L Durand |
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| Institution: | Unitéd'Ecophysiologie des Plantes Fourragères, Institut National de la Recherche Agronomique, F-86 600 Lusignan, France,;Unitéde Physiologie Intégrée des Arbres Fruitiers, Institut National de la Recherche Agronomique, F-63 039 Clermont-Ferrand, France |
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| Abstract: | The water relations and hydraulic architecture of growing grass tillers (Festuca arundinacea Schreb.) are reported. Evaporative flux density, E (mmol s?1 m?2), of individual leaf blades was measured gravimetrically by covering or excision of entire leaf blades. Values of E were similar for mature and elongating leaf blades, averaging 2·4 mmol s?1 m?2. Measured axial hydraulic conductivity, Kh (mmol s?1 mm MPa?1), of excised leaf segments was three times lower than theoretical hydraulic conductivity (Kt) calculated using the Poiseuille equation and measurements of vessel number and diameter. Kt was corrected (Kt*) to account for the discrepancy between Kh and Kt and for immature xylem in the basal expanding region of elongating leaves. From base to tip of mature leaves the pattern of Kt* was bell‐shaped with a maximum near the sheath–blade joint (≈ 19 mmol s?1 mm MPa?1). In elongating leaves, immature xylem in the basal growing region led to a much lower Kt*. As the first metaxylem matured, Kt* increased by 10‐fold. The hydraulic conductances of the whole root system,  and leaf blades, <img loading=) | |
| Keywords: | electric-circuit analogue elongating leaf hydraulic architecture hydraulic conductivity leaf transpiration water relations |
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