نتایج جستجو برای: xylem

تعداد نتایج: 4505  

2014
Rosana Lopez Eric Badel Sebastien Peraudeau Nathalie Leblanc-Fournier François Beaujard Jean-Louis Julien Hervé Cochard Bruno Moulia

When tree stems are mechanically stimulated, a rapid long-distance signal is induced that slows down primary growth. An investigation was carried out to determine whether the signal might be borne by a mechanically induced pressure pulse in the xylem. Coupling xylem flow meters and pressure sensors with a mechanical testing device, the hydraulic effects of mechanical deformation of tree stem an...

Journal: :Journal of experimental botany 2003
Maciej A Zwieniecki Colin M Orians Peter J Melcher N Michele Holbrook

Ions can enhance water flow through the xylem via changes in the hydraulic resistance at border pit membranes. Because flow between adjacent xylem vessels occurs primarily via bordered pit fields, it is hypothesized that xylem sap ion concentrations would affect lateral movement of water more than longitudinal flow. Using tomato as a model system, evidence is presented for ion-mediated changes ...

Journal: :Plant, cell & environment 2011
Sanna Sevanto Teemu Hölttä N Michele Holbrook

Measurements of diurnal diameter variations of the xylem and phloem are a promising tool for studying plant hydraulics and xylem-phloem interactions in field conditions. However, both the theoretical framework and the experimental verification needed to interpret phloem diameter data are incomplete. In this study, we analytically evaluate the effects of changing the radial conductance between t...

Journal: :Plant physiology 1978
W Heyser R F Evert E Fritz W Eschrich

Following exposure of portions of mature maize (Zea mays L.) leaf strips to (14)CO(2), xylem exudate from the leaf strips contained [(14)C]sucrose. Sucrose was the only sugar in the xylem exudate which was obtained from the cut surface of the leaf strips by reducing the external pressure. The sucrose found in the xylem exudate apparently was obtained from the free space of the vascular bundles,...

Journal: :The New phytologist 2016
Sean M Gleason Mark Westoby Steven Jansen Brendan Choat Uwe G Hacke Robert B Pratt Radika Bhaskar Tim J Brodribb Sandra J Bucci Kun-Fang Cao Hervé Cochard Sylvain Delzon Jean-Christophe Domec Ze-Xin Fan Taylor S Feild Anna L Jacobsen Daniel M Johnson Frederic Lens Hafiz Maherali Jordi Martínez-Vilalta Stefan Mayr Katherine A McCulloh Maurizio Mencuccini Patrick J Mitchell Hugh Morris Andrea Nardini Jarmila Pittermann Lenka Plavcová Stefan G Schreiber John S Sperry Ian J Wright Amy E Zanne

The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well-known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and spread) should trade off against xylem efficien...

Journal: :Cryobiology 2007
Jun Kasuga Kaoru Mizuno Keita Arakawa Seizo Fujikawa

Boreal hardwood species, including Japanese white birch (Betula platyphylla Sukat. var. japonica Hara), Japanese chestnut (Castanea crenata Sieb. et Zucc.), katsura tree (Cercidiphyllum japonicum Sieb. et Zucc.), Siebold's beech (Fagus crenata Blume), mulberry (Morus bombycis Koidz.), and Japanese rowan (Sorbus commixta Hedl.), had xylem parenchyma cells (XPCs) that adapt to subfreezing tempera...

Journal: :Plant physiology 1985
R E Dickson T C Vogelmann P R Larson

The distribution of (14)C from xylem-borne [(14)C]glutamine, the major nitrogen compound moving in xylem sap of cottonwood (Populus deltoides Bartr. ex Marsh), was followed in rapidly growing shoots with a combination of autoradiographic, microautoradiographic, and radioassay techniques. Autoradiography and (14)C analyses of tissues showed that xylem-borne glutamine did not move with the transp...

Journal: :Plant, cell & environment 2017
R Brandon Pratt Anna L Jacobsen

The secondary xylem of woody plants transports water mechanically supports the plant body and stores resources. These three functions are interdependent giving rise to tradeoffs in function. Understanding the relationships among these functions and their structural basis forms the context in which to interpret xylem evolution. The tradeoff between xylem transport efficiency and safety from cavi...

2012
Yaosheng Wang Fulai Liu Christian Richardt Jensen

Comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on xylem pH, ABA, and ionic concentrations of tomato (Lycopersicon esculentum L.) plants were investigated in two split-root pot experiments. Results showed that PRI plants had similar or significantly higher xylem pH, which was increased by 0.2 units relative to DI plants. Nitrate and total ionic concentratio...

Journal: :Plant physiology 2009
Taylor S Feild David S Chatelet Tim J Brodribb

Flowering depends upon long-distance transport to supply water for reproductive mechanisms to function. Previous physiological studies suggested that flowers operated uncoupled from stem xylem transport and received water primarily from the phloem. We demonstrate that the water balance of Southern magnolia (Magnolia grandiflora) flowers is regulated in a manner opposite from that of previously ...

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