Effects of Salinity on Growth, Water Relations and Ion Accumulation of the Subtropical Perennial Halophyte, Atriplex griffithii var. stocksii

Abstract

The effects of salinity on growth, water relations, glycinebetaine content, and ion accumulation in the perennial halophyte Atriplex griffithii var. stocksii were determined. The following questions were addressed: (1) What effect does salinity have on growth responses at different ages? (2) Is A. griffithii an ion accumulator? (3) Does A. griffithii accumulate glycinebetaine in response to salinity? Atriplex griffithii plants were grown in pots at 0, 90, 180 and 360 m m NaCl in sand culture in a plant growth chamber and plants were harvested after 30, 60 and 90 d. Plant total dry weight was significantly inhibited at 360 m m NaCl. Root growth showed a substantial promotion at 90 m m NaCl. The water potential and osmotic potential of shoots became more negative with increasing salinity and time of growth. The Na + and Cl − content in both shoots and roots increased with increases in salinity. Increased treatment levels of NaCl induced decreases in Ca + , K + and Mg 2+ in plants. Atriplex griffithii accumulated a large quantity of ions, with the ash content reaching 39% of the dry weight in leaves. Inorganic ion accumulation is significant in osmotic adjustment and facilitates water uptake along a soil-plant gradient. Glycinebetaine concentration was low in roots, and in stems it increased with increases in salinity. Total amounts of glycinebetaine in leaves increased with increases in salinity, and its concentration increased substantially at 360 m m NaCl. Copyright 2000 Annals of Botany Company