Transfer of salt and nutrients in Bruguiera gymnorrhiza leaves during development and senescence

The life span of leaves in Bruguiera gymnorrhiza, non-secretor of salt, can be divided into a leaf developing stage, a leaf functioning stage and a leaf senescing stage. The concentrations (mg/g) and the contents (mg/leaf) of Na and Cl increased at the leaf developing stage and remained almost constant at the leaf functioning stage. At the leaf senescing stage, the concentrations of Na and Cl increased markedly by 45 and 31% respectively, while their contents only increased by 16 and 4% respectively. The K/Na ratio remained constant at the leaf functioning stage, and decreased at the leaf senescing stage. During leaf senescence, there was a marked decline in leaf mass (20%) and in leaf area (15%). During senescence, 60% of its N, 48% of its P and 46% of its K was transferred out of the senescing leaf.