PROVENANCE SELECTION OF EUCALYPTUS MICROTHECA FOR AFFORESTATION IN ARID AND SEMI-ARID AREAS

摘要

In Australia, the natural distribution of Eucalyptus species is strongly influenced by the resistance of seedlings to drought. Survival strategies in response to water deficit at the initial seedling growth phase have been studied (Bachelard 1986; Wang et al. 1988; Davidson and Reid, 1989; Myers and Landsberg, 1989; Gibson and Bachelard, 1994; Gibson et al. 1991, 1994, 1995; Lemcoff et al. 1994; Anderson et al. 1996). Some of the adaptive responses to water deficit cause changes in plant structure, growth rates, water use efficiency, tissue osmotic potential and stomatal conductance among others, (Jones, 1992). Eucalyptus microtheca F. Muell is characteristically a species of open woodlands which has a wide and patchy natural distribution in the arid and semi-arid zone of Australia, It is well adapted and widely distributed to dry environments from the west to the east of Australia and has a large genotypic variation (Boland et al, 1984). Its ability to adapt to different natural habits has contributed to its successful introduction as an exotic plant species in many irrigation schemes in arid and semi-arid lands (Mustafa, 1989 and Schiller, 1995) The main use of the species are fuelwood and poles, shelterbelts and soil stabilisation Tuomela et al. (1993) and Tuomela (1997a) showed that seedlings from different climatic zones differ in morphological and physiological characteristics in response to water stress. However, little work has been done on seedling establishment, survival and growth pattern under water deficit.