Seasonal water relations of Lyginia barbata (Southern rush) in relation to root xylem development and summer dormancy of root apices
Article first published online: 18 JAN 2010
© The Authors (2010). Journal compilation © New Phytologist (2010)
Volume 185, Issue 4, pages 1025–1037, March 2010
How to Cite
Shane, M. W., McCully, M. E., Canny, M. J., Pate, J. S., Huang, C., Ngo, H. and Lambers, H. (2010), Seasonal water relations of Lyginia barbata (Southern rush) in relation to root xylem development and summer dormancy of root apices. New Phytologist, 185: 1025–1037. doi: 10.1111/j.1469-8137.2009.03143.x
- Issue published online: 9 FEB 2010
- Article first published online: 18 JAN 2010
- Received: 8 September 2009, Accepted: 28 October 2009
- cryo-energy dispersive X-ray microanalysis;
- cryo-scanning electron microscopy;
- dormant roots;
- drought resistance;
- xylem differentiation;
- xylem–phloem juxtaposition
- •Periods of dormancy in shallow roots allow perennial monocotyledons to establish deep root systems, but we know little about patterns of xylem maturation, water-transport capacities and associated economies in water use of growing and dormant roots.
- •Xylem development, anatomy, conductance and in situ cellular [K] and [Cl] were investigated in roots of field-grown Lyginia barbata (Restionaceae) in Mediterranean southwestern Australia. Parallel studies of gas exchange, culm relative water loss and soil water content were conducted.
- •Stomatal conductance and photosynthesis decreased during summer drought as soil profiles dried, but rates recovered when dormant roots became active with the onset of wetter conditions. Anatomical studies identified sites of close juxtaposition of phloem and xylem in dormant and growing roots. Ion data and dye tracing showed mature late metaxylem of growing roots was located ≥ 100 mm from the tip, but at only ≤ 10 mm for dormant roots. Dormant roots remained hydrated in dry soils (0.001–0.005 g g−1).
- •Effective regulation of growth and water-conserving/obtaining properties permits the survival of shallow roots of L. barbata during summer drought and may represent important strategies for establishing deeper perennial root systems in other monocotyledonous plants adapted to seasonally dry habitats.