Báo cáo lâm nghiệp: Variations in seed and seedling responses to water stress in three provenances of Eucalyptus camaldulensis Dehnh

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Báo cáo lâm nghiệp: "Variations in seed and seedling responses to water stress in three provenances of Eucalyptus camaldulensis Dehnh"Variations in seed and seedling responses to waterstress in three provenances of Eucalyptus camaldulen-sis Dehnh.A. Gibson E.P. BachelardDepartment of Forestry, Australian National University, Canberra, :tralia UE A those used previously (Gibson and Bachelard,Introduction 1987). The initial establishment (hypocotyl raised, cotyledons opened) of seedlings from germinated seeds placed on the surface of soilsPrevious work (Bachelard, 1985, 1986a, at different moist:ure contents (35, 18 and 10%,b; Gibson and Bachelard, 1987; Yang et w/w) in containers in a controlled environmental., 1988) has shown that seeds and seed- cabinet was observed, and early seedlinglings of eucalypt species, subspecies and growth measured. Effects of water stress (10%provenances within a species may differ in s.m.c. for 6 wk) on tissue-water relations, water use efficiency, partitioning of dry matter intotheir germination and growth responses to roots, stems and leaves, leaf growth and mor-water stress. Seeds from 3 provenances phology were also determined in 8 wk old seed-of Eucalyptus camaldulensis Dehnh. dif- lings grown in pots in a glasshouse with andfered in their abilities to germinate under without added fertiliser.different atmospheric vapour pressuredeficits (VPD) and plate matric potentialsin a manner consistent with the moisture Resultsconditions in the environment in whichthese provenances occur naturally (Gib-son and Bachelard, 1987). In this study, Establishment and early seedling growththe effects of water stress on the initialestablishment and early growth of seed- established from most seeds Seedlingslings from 3 provenances of E. camaldu- the surface of soils at 35% sown onlensis were examined. s.m.c., with slightly fewer Katherine seed- establishing (Table I). Fewer seed- lings established from seeds sown on d 2 lingsMaterials and Methods due to the drying of the soil surface between d 1 and 2. At 18% s.m.c., Petford seedlings established best andThe 3 provenances of E. camaldulensis (Kathe- Katherine seedlings worst. These dif-rine and Petford from monsoonal sites; Tennant ferences in establishment were associatedCreek from a semi-arid site) were the same aswith differences between provenances in to the soil and assist early seedling firmly uptake. Shoot growth of Petfordthe production of hairs on the collar of ger- waterminating seedlings (Fig. 1which bind the seedlings was best at high s.m.c. but, at low s.m.c., the few Tennant Creek seed- III lings whose radicle penetrated the soil grew best (Fig. 2). of older Response seedlings to water stress Osmotic potentials of seedlings from all provenances were lowered similarly (by ...