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University of Toronto (1995)

Preconditioning responses of salt-tolerant and salt-sensitive provenances of Acacia tortilis (Forsk.) Hayne to high salinity

Park, Andrew David

Titre : Preconditioning responses of salt-tolerant and salt-sensitive provenances of Acacia tortilis (Forsk.) Hayne to high salinity

Auteur : Park, Andrew David

Université de soutenance : University of Toronto (Canada)

Grade : Master of Science in Forestry 1995

Résumé Growth and nutrient responses to NaCl preconditioning treatments were studied in two seed provenances of Acacia tortilis (Forsk.) Hayne from saline (Sigor) and non-saline (Kitui) areas of Kenya. Seedlings were exposed to NaCl preconditioning treatments at 15, 21, and 28 days after germination. Subsequently, all seedlings were exposed to 200 millimolal NaCl for a further 39 days to test the efficacy of the different preconditioning schedules in hardening seedlings of different ages to high salinity. Nutrient analysis showed that Sigor initially partitioned a greater proportion of total Na+ uptake to roots than shoots. Both provenances had similar contents of macronutrients and Na+ by the final harvest of the experiment. However, all ions were more concentrated in Kitui than Sigor, probably as a combined result of Kitui’s lower growth and less efficient partitioning of Na+ . Multivariate ordinations confirmed the sensitivity of leaf abscission and shoot growth as variables associated with salt-tolerance, and suggested that the effects of Na+ were felt as much through disturbances in nutrient metabolism as they were through direct-ion toxicity.

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