%0 Journal Article %1 citeulike:2873240 %A Nobel, Park S. %A Jordan, Peter W. %D 1983 %J J. Exp. Bot. %K citeulikeExport diameter, grass, hydraulics, leaf %N 10 %P 1379--1391 %R 10.1093/jxb/34.10.1379 %T Transpiration Stream of Desert Species: Resistances and Capacitances for a C3, a C4, and a CAM Plant %U http://dx.doi.org/10.1093/jxb/34.10.1379 %V 34 %X Transpiration rates and water potentials of three sympatric desert perennials, a C3 subshrub (Encelia farinosa), a C4 bunchgrass (Hilaria rigida), and a CAM succulent (Agave deserti), were analysed using an electrical circuit analogue that included resistances and capacitances for the leaves, stems, and roots. The water storage capability of the organs differed considerably, capacitance ranging over 1000-fold from the thin leaves of H, rigida to the massive leaves of A. deserti, although the capacitance per unit volume varied only 1.9-fold. The diurnal changes in water storage could support maximum transpiration rates of H. rigida for 4 min, E. farinosa for 7 min, and A. deserti for 16 h. The time constant for equilibration of water from storage to the xylem ranged from 29 s for roots of H. rigida to 52 min for leaves of A. deserti. Resistances for such movement were relatively low for the succulent leaves of A. deserti and were up to about 50-fold higher for the three organs of E. farinosa. Xylem resistances calculated using the Hagen-Poiseuille law and measured xylem dimensions were 2.1- to 2.1-fold lower than resistances estimated from observed water potential drops, a discrepancy which is in agreement with other published data. Contrary to data on other plants, the xylem resistances in the roots and leaves of E. farinosa and H. rigida averaged only 15\% of the stem xylem resistance. 10.1093/jxb/34.10.1379

@article{citeulike:2873240, abstract = {{Transpiration rates and water potentials of three sympatric desert perennials, a C3 subshrub (Encelia farinosa), a C4 bunchgrass (Hilaria rigida), and a CAM succulent (Agave deserti), were analysed using an electrical circuit analogue that included resistances and capacitances for the leaves, stems, and roots. The water storage capability of the organs differed considerably, capacitance ranging over 1000-fold from the thin leaves of H, rigida to the massive leaves of A. deserti, although the capacitance per unit volume varied only 1.9-fold. The diurnal changes in water storage could support maximum transpiration rates of H. rigida for 4 min, E. farinosa for 7 min, and A. deserti for 16 h. The time constant for equilibration of water from storage to the xylem ranged from 29 s for roots of H. rigida to 52 min for leaves of A. deserti. Resistances for such movement were relatively low for the succulent leaves of A. deserti and were up to about 50-fold higher for the three organs of E. farinosa. Xylem resistances calculated using the Hagen-Poiseuille law and measured xylem dimensions were 2.1- to 2.1-fold lower than resistances estimated from observed water potential drops, a discrepancy which is in agreement with other published data. Contrary to data on other plants, the xylem resistances in the roots and leaves of E. farinosa and H. rigida averaged only 15\% of the stem xylem resistance. 10.1093/jxb/34.10.1379}}, added-at = {2019-03-31T01:14:40.000+0100}, author = {Nobel, Park S. and Jordan, Peter W.}, biburl = {https://www.bibsonomy.org/bibtex/272a09207fd27ac67d97ba5e62b01d715/dianella}, citeulike-article-id = {2873240}, citeulike-linkout-0 = {http://dx.doi.org/10.1093/jxb/34.10.1379}, citeulike-linkout-1 = {http://jxb.oxfordjournals.org/cgi/content/abstract/34/10/1379}, comment = {(private-note)Indeed, smaller xylem diameter was apparently the main factor contributing to the larger water potential drops in the roots and stems of H. rigida (Fig. 2). pressure volume curves estimate capacitance therefore water movement into and out of storage in the leaf / stem or root Resistances predicted by the Hagen-Poiseuille law were smaller than those actually measured by 2-1- to 21-fold (Table 2). Similar results were obtained for tomato, where the predicted resistances of individual xylem vessels averaged 10-fold less than those measured (Giordano et al^ 1978), and for seven species of ferns, where predicted pressure gradients were 3- to 5-fold less than those measured (Woodhouse and Nobel, 1982). This discrepancy has been related to roughness of xylem lumen walls, the presence of perforation plates, and other obstructions (Jeje and Zimmermann, 1979). Interspecific differences in water storage may reflect the strategies that different species have to buffer changes in water potential or water content in a fluctuating environment. The large capacitance of succulents such as A. deserti, combined with low stomatal conductance to water loss, helps buffer their tissues from seasonal droughts. The lower capacitances for H. rigida and E. farinosa, resulting in lower water potentials for a given loss of tissue water, allow these species to extract water more readily from soil at low y/50".}, day = 1, doi = {10.1093/jxb/34.10.1379}, interhash = {ad806a8372b100f48f8150861b24ce61}, intrahash = {72a09207fd27ac67d97ba5e62b01d715}, journal = {J. Exp. Bot.}, keywords = {citeulikeExport diameter, grass, hydraulics, leaf}, month = oct, number = 10, pages = {1379--1391}, posted-at = {2008-06-08 08:50:58}, priority = {2}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{Transpiration Stream of Desert Species: Resistances and Capacitances for a C3, a C4, and a CAM Plant}}, url = {http://dx.doi.org/10.1093/jxb/34.10.1379}, volume = 34, year = 1983 }