Influence of light and darkness and the experimental design on kinetics of potassium rubidium 86 influx in roots of intact spring wheat triticum aestivum cultivar svenno

Jensen, P.; Pettersson, S.

Physiologia Plantarum 60(1): 65-69

1984


ISSN/ISBN: 0031-9317
DOI: 10.1111/j.1399-3054.1984.tb04251.x
Accession: 005687135

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Abstract
Seedlings of spring wheat were cultivated at 20.degree.C in continuous light or darkness with the roots in nutrient solutions for 6 days. The plants were starved for K+ during different periods of time to produce plants with various K+ status. In 1 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 mM K+ radiolabeled with 86Rb. 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+ (86Rb) influx in the roots decreased. The sigmoidal relationship obtained between K+ (86Rb) influx and [K+]root was affected by these changes, and Hill plots gave various Hill coefficients, nH, depending on the duration of the uptake experiments, nH from 3 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.

Influence of light and darkness and the experimental design on kinetics of potassium rubidium 86 influx in roots of intact spring wheat triticum aestivum cultivar svenno