Vol. 82 No: 2

Title:
Diurnal and seasonal changes in the xylem water potentials of Grevillea and Myoporum plants during drought

Authors:
SHENGGEN HE and DARYL C. JOYCE

pp: 290-296

Abstract:
Drought is an irregular feature of World climate and has adverse effects on ornamental plants growing in urban environments. Grevillea ´Moonlight` and Myoporum elipticum are attractive native Australian species that are commonly used in parks and gardens and are generally regarded as being drought-tolerant. Diurnal and seasonal water relations during a drought cycle of G. ´Moonlight` and M. elipticum, growing together in a non-irrigated garden bed, were monitored during a Summer (wetter)-to-Winter (dryer) transition period using a pressure chamber. G. ´Moonlight` generally maintained higher xylem water potentials than M. elipticum. Pre-dawn xylem water potentials in drought-affected M. elipticum dropped to around -2.5 MPa, while G. ´Moonlight` maintained pre-dawn xylem water potentials of around -1.0 MPa. This difference suggests that, because pre-dawn xylem water potentials reflect soil water potentials,G. ´Moonlight` accessed a different or additional source of soil water to M. elipticum. This study demonstrates the utility of the pressure chamber for describing the diurnal and seasonal water relations of ornamentals in a mixed planting in urban horticulture.

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