tailieunhanh - Báo cáo lâm nghiệp: "Ionic interactions between precipitation and leaf cuticles"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Ionic interactions between precipitation and leaf cuticles. | 557s Ann. Sci. For. 1989 46 suppl. 557s-560s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Ionic interactions between precipitation and leaf cuticles T. Scherbatskoy University of Vermont Botany Department Burlington VT 05405 . Introduction The leaf cuticle is the most important ratelimiting barrier controlling the movement of solutes between precipitation and the leaf interior but the mechanisms and rates by which ions diffuse through the cuticle remain poorly defined. There is strong experimental evidence that cuticles contain hydratable pores up to nm in radius lined with polar groups McFarlane and Berry 1975 Schõnherr 1979 Seymour 1980 . These hydrophilic regions in cuticles probably incorporate the polar substituents of waxes and cutin as well as polyuronic acids of the polysaccharides in the secondary cuticle. These polar groups and polar pores are likely to contribute greatly to the ion exchange capacity and transport properties of cuticles. This research examined the ionic interactions between leaf surfaces and precipitation particularly the role of the leaf cuticle in mediating ion transport into and out of the leaves. Materials and Methods Ionic exchange Individual 50 pi drops of artificial precipitation representing regional ambient precipitation at pH or were applied to adaxial and abaxial surfaces of mature field-grown Acer sac-charum leaves which had been rinsed with deionized water. Ten experiments were conducted at weekly intervals between July and September in a high-humidity chamber to reduce drop evaporation. Drops were quantitatively removed after precise times beiween 4 and 128 min and analyzed for Cu2 Pb2 Zn2 K Ca2 and Mg2 . Electrophysiology Adaxial cuticles were enzymatically isolated Orgell 1955 from mature leaves of several tree species. Diffusion potentials across cuticles were measured in a flow-cell by pumping unbuffered salt solutions across the two sides of the cuticle to create ion concentration .

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