Root Xylem Embolisms and Refilling. Relation to Water Potentials of Soil, Roots, and Leaves, and Osmotic Potentials of Root Xylem Sap1
AUTOR(ES)
McCully, Margaret E.
FONTE
American Society of Plant Physiologists
RESUMO
Embolism and refilling of vessels was monitored directly by cryomicroscopy of field-grown corn (Zea mays L.) roots. To test the reliability of an earlier study showing embolism refilling in roots at negative leaf water potentials, embolisms were counted, and root water potentials (Ψroot) and osmotic potentials of exuded xylem sap from the same roots were measured by isopiestic psychrometry. All vessels were full at dawn (Ψroot −0.1 MPa). Embolisms were first seen in late metaxylem vessels at 8 am. Embolized late metaxylem vessels peaked at 50% at 10 am (Ψroot −0.1 MPa), fell to 44% by 12 pm (Ψroot −0.23 MPa), then dropped steadily to zero by early evening (Ψroot −0.28 MPa). Transpiration was highest (8.5 μg cm−2 s−1) between 12 and 2 pm when the percentage of vessels embolized was falling. Embolized vessels were refilled by liquid moving through their lateral walls. Xylem sap was very low in solutes. The mechanism of vessel refilling, when Ψroot is negative, requires further investigation. Daily embolism and refilling in roots of well-watered plants is a normal occurrence and may be a component of an important hydraulic signaling mechanism between roots and shoots.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=32080Documentos Relacionados
- Phosphorus and Sulfur Compounds in Plant Xylem Sap1
- Abscisic Acid and Transpiration in Leaves in Relation to Osmotic Root Stress 1
- Osmotic Adjustment in Cotton (Gossypium hirsutum L.) Leaves and Roots in Response to Water Stress 1
- CONDUCTIVITY MEASUREMENTS OF PLANT SAP1
- Expression of Candida albicans SAP1 and SAP2 in experimental vaginitis.