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Abstract
Salt stress decreases crop yield worldwide. I conducted two experiments using cultivated sunflower (Helianthus annuus) to improve understanding of salinity tolerance and the role of vigor and organ elemental concentrations therein. Vigor correlated with lower salt tolerance (greater proportional change in biomass). However, inconsistent genotypic rankings for vigor and tolerance suggest different tolerance mechanisms function at different times and stress intensities. When examining elemental allocation as a mechanism of tolerance, a combined allocation of less Na away from, more P and Zn away from, and an allocation of Fe away from mature leaves correlated with greater tolerance, though the physiological basis of the relationships are currently unknown. While providing direction for future studies, this thesis showed that defining salt tolerance as the proportional change in performance and analyzing elemental allocation between diverse organs can provide greater inference into salt tolerance mechanisms.