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Influence of light and darkness and the experimental design on kinetics of K + ( 86 Rb) influx in roots of intact spring wheat
Author(s) -
Jensén Paul,
Pettersson Sune
Publication year - 1984
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 - 10.1111/j.1399-3054.1984.tb04251.x
Subject(s) - darkness , nutrient , chemistry , botany , cooperativity , horticulture , biology , biochemistry , organic chemistry
Seedlings of spring wheat ( Triticum aestivum L. cv. Svenno) were cultivated at 20°C in continuous light or darkness with the roots in nutrient solutions for six days. The plants were starved for K + during different periods of time to produce plants with various K + status. In one cultivation light‐grown plants were pretreated in darkness, and vice versa, before the uptake experiment. In all experiments, roots were put in a complete nutrient medium containing 2.0 m M K + radiolabelled with 86 Rb. The uptake time was varied (5, 60 or 120 min). The K + concentration in the roots, [K + ] root , increased during the course of the uptake experiments, especially in light and at initially low [K + ] root , At the same time K + ( 86 Rb) influx in the roots decreased. The simoidal relationship obtained between K + ( 86 Rb) influx and [K + ] root was affected by these changes, and Hill plots gave various Hill coefficients, n H , depending on the duration of the uptake experiments. n H from three apparently straight line segments of the same plot, in different [K + ] root ‐ intervals, indicated a falling degree of interaction between the binding sites as [K + ] root increased. For the dark‐grown plants negative cooperativity could not be demonstrated.