In vivo Chlorophyll a Fluorescence in Sodium-Deficient C₄ Plants

Abstract

The fluorescence ratio (F_p-F_I)/F_I gave a consistent value when leaf tissue weights greater than 0.1 g were used and was lower in sodium-deficient than normal C₄ plants. Of the group I elements only sodium, irrespective of the salt supplied to deficient cultures, increased the fluorescence ratio to that observed in normal plants. The concentration of sodium required to increase the fluorescence ratio corresponded to the concentration of sodium required to bring about a growth response in Kochia childsii. The application of sodium, either directly onto the leaves or via the culture solution, brought about a rapid and parallel increase in the chlorophyll a/b ratio and the fluorescence ratio in K. childsii.