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Accueil du site → Doctorat → Australie → 1995 → Saltbush growth and soil properties from southeastern Australian semi-arid rangelands with dieback and salinity problems

University of New South Wales (1995)

Saltbush growth and soil properties from southeastern Australian semi-arid rangelands with dieback and salinity problems

Jafari, Mohammad

Titre : Saltbush growth and soil properties from southeastern Australian semi-arid rangelands with dieback and salinity problems

Auteur : Jafari, Mohammad

Université de soutenance : University of New South Wales

Grade : Doctor of Philosophy PhD 1995

Résumé
Salinity and dieback are two significant problems of rangelands and these were studied on the Hay Plain of southern New South Wales, Australia. Sites were selected to show dieback, non-dieback and some had scalded soil surfaces but all soils were salinized to some degree. Relationships of saltbush growth and soil properties concerning salinity and potassium availability were studied in the field and glasshouse including differences between dieback and non-dieback sites. A wide range of properties were measured for soils from all sites. Differences between scald soils and other soils were apparent. No difference was observed between dieback and non-dieback sites in terms of soil properties, but field and laboratory studies showed several differences between the sites. Plants from dieback sites showed less protein content than those from non-dieback sites and a stronger relationship existed between shrub volume and mass on dieback sites. Several glasshouse experiments were undertaken. For comparison between dieback and non-dieback sites seedlings of Atriplex vesicaria (perennial) and A. holocarpa (annual) were planted in eight different soils (4 dieback and 4 non-dieback). Differences in survival and growth of seedlings were detected and damping-off fungal disease was a particular problem. Atriplex holocarpa’s growth was greater than A. vescaria, but damping-off in A. vesicaria was less than A. holocarpa. Atriplex holocarpa and A. lindleyi were planted in the eight different soils but with five treatments of added salts to increase natural salinity. The fungicide Phenyl Mercuric Acetate was used to control damping-off which was a greater problem in dieback soils. The salinity treatments adopted had no impact on growth so a new regime of increased salinity treatments were applied in a third series of experiments. These increased salinity treatments used seedlings of Atriplex semibaccata and Terraclor fungicide to control damping-off by Rhizoctonia solani. The original eight soils were studied together with naturally saline, sandy and scalded soils. These experiments showed that the addition of potassium to soils with low salinity treatment, increased the availability of potassium in the soil and lessened the impact on growth of the salinity. A number of management practices that could be trialled to ameliorate saline and dieback conditions are reviewed.

Mots clés : Salt-bush Australia • Dieback Australia • Salinity Australia

Présentation

Accès au document : Proquest Dissertations & Theses

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