Chronophysiological rhythm model for daily ionic variation of xylematic exudates in tomato plants

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.