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K + status and ABA affect both exudation rate and hydraulic conductivity in sunflower roots
Author(s) -
Quintero José M.,
Fournier José M.,
Ramos José,
Benlloch Manuel
Publication year - 1998
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1998.1020216.x
Subject(s) - helianthus annuus , sunflower , hydraulic conductivity , xylem , potassium , botany , chemistry , transpiration , osmotic pressure , conductivity , horticulture , biology , soil water , photosynthesis , ecology , organic chemistry
Twenty‐day‐old sunflower plants ( Helianthus annuus L. cv. Sun‐Gro 380) grown in nutrient solutions with different KCl levels were used to study the effects of K + status of the root and of abcisic acid (ABA) on the exudation rate (J v ), the hydraulic conductivity of the root (L p ), the fluxes of exuded K + and Na + (J K and J Na ), and the gradient of osmotic pressure between the xylem and the external medium. J v and L p increased in direct proportion to the K + starvation of the root. Also addition of ABA (4 µ M ) at the onset of exudation in the external medium made J v and L p rise, and this effect also increased with the degree of K + starvation. Similarly, K + starvation and ABA promoted both the flux of exuded Na + and the accumulation of Na + in the root. We suggest that ABA acts as a regulating signal for the radial transport of water across the root, and that potassium may be an effector of this mechanism.