Browsing by Author "Tonsi, Brittany"
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- ItemEffects of NaCl and CaCl2 salinity stress on the germination, seedling and root morphology of Dalea candida(2020) Tonsi, Brittany; Christensen-Dalsgaard, KarenCalcium chloride (CaCl2) and sodium chloride (NaCl) are commonly used de-icing agents that result in saline-contaminated soils. Little is known about the effects of CaCl2 on plant germination, growth, and development. The purpose of this study was to compare the effects of CaCl2 and NaCl on germination and true leaf development of Dalea candida, a native legume of central North America. We further examined comparative effects on root growth and morphology at the initial germination phase. We used a controlled growth experiment consisting of various concentrations of NaCl (62.5mM and 125mM) and CaCl2 (31.25mM and 62.5mM) in soil and Petri dishes. While both salts exhibited negative trends, CaCl2 had less of an effect on the germination rate (64% at 31.25mM); however, aboveground true leaf development was stunted. NaCl at 62.5mM and 125mM exhibited a significantly lower mean root length and wider mean root diameter relative to comparable concentrations of CaCl2. Furthermore, only NaCl treatments significantly inhibited root hair presence. Our results indicate that while CaCl2 had less of a negative effect on initial germination, both salts stunt aboveground growth and development of D. candida seedlings via different mechanisms.
- ItemEffects of salinity stress on the germination, survival, and legume-rhizobial symbiosis of native legume Dalea purpurea(2020) Baran, Nicklas; Tonsi, Brittany; Christensen-Dalsgaard, KarenSoil salinity poses a major challenge for oil sands reclamation in Alberta. Sodium chloride is an abiotic stressor that negatively affects plants physiologically causing a need to identify native plant species capable of surviving and improving the soil conditions of these sites. Dalea purpurea (Fabaceae) is a promising candidate for oil sands reclamation, but no research has been done to assess its salinity tolerance and the effect of salinity on its Rhizobial symbiosis. In the present laboratory study, we subjected D. purpurea seedlings to pre-germination conditions of 0, 25, and 50mM NaCl, in the presence and absence of Rhizobial symbionts. We found a significant decrease in germination success and post-germination survival as a result of salinity with salt-sensitivity varying among individuals. Surviving individuals in salinity treatments displayed growth comparable to control treatments. Salinity did not affect nodulation, but significantly reduced nodule volume by 56% at 50mM NaCl. While nodule health of the species is negatively impacted by salinity, the species may be useful in salinity reclamation due to the presence of salt-tolerant individuals. This is the first study to consider the utility of native legumes and their rhizobial symbionts for the reclamation of saline oil sands sites.