title: Na+ accumulation in shoot is related to water transport in K+-starved sunflower plants but not in plants with a normal K+ status.
abstract: Sunflower plants (Helianthus annuus L. cv Sun-Gro 380) grown in nutrient solutions with different K+ levels were used to study the effect of potassium status on water uptake, Na+ uptake and Na+ accumulation in the shoot. Changes in nutrient potassium levels induced evident differences in internal potassium content. When both low and normal-K+ plants were exposed to 22 degrees C and salinity conditions (25 or 50 mM NaCl) during a short time period (9h), water uptake in low-K+ plants was greater than in normal-K+ plants. In addition, K+ starvation favoured the Na+ uptake and the Na+ accumulation both in the root and in the shoot. When the plants were exposed to heat stress by a sharp increase of the temperature to 32 degrees C during the same period of time, the stimulating effect of K+ starvation on the water uptake was even greater. The high temperature increased Na+ uptake in both types of plants, but the Na+ accumulation in the shoot was only favoured in low-K+ plants. The results suggest that Na+ accumulation in the shoot is more dependent on the water uptake in low-K+ plants than in normal-K+ plants, and this effect could explain the greatest susceptibility to the salinity in K+-starved plants under high transpiration conditions, which are typical in dry climates.
authors.affiliation: Departamento de Ciencias Agroforestales, Escuela U. Ingeniería Técnica Agrícola, Universidad de Sevilla, Ctra. Utrera, Km. 1, E-41013 Sevilla, Spain. jqariza@us.es
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Quintero
authors.forename: José María
authors.initials: JM
authors.lastname: Fournier
authors.forename: Manuel
authors.initials: M
authors.lastname: Benlloch
mesh_terms: D001692:Biological Transport; D006368:Helianthus / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013696:Temperature; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water; D012964:Sodium; D011188:Potassium