Abstract

Ten-day-old tomato plants Lycopersicon esculentum Mill. cv. Rambo were transplanted in a NFT special system. The experiment was repeated three consecutive times. Each experiment consisted of three replicates. The experiments were carried out with 45-day-old plants. Xylem sap samples were obtained by decapitating the plant during the 35th day in NFT at about 1 cm above the root system. The sap flux rate was strongly correlated (p > 0.999) with the proposed model of a chronophysiological rhythm. Diurnal variations of inorganic ions clearly indicate that ion transport rates varied widely with time and also followed a proposed chronophysiological rhythm. The rhythmic model presented may provide a framework for the explanation of short- and long-term variations in xylem sap concentration-flux relationships. Additionally they may contribute to the knowledge of long distance transport processes and the variations in nutrient uptake by plants.