Biomass partitioning in canola (Brassica napus) and the characterization of leaf anatomical structures
Creators: Liza, Saima Jahan
Publisher: name: University of Alberta Library
Year: 2024

<p>Canola is the predominant crop grown on the Canadian Prairies, contributing about $26.7 billion to the economic activities per year in Canada. In 2023, Canada produced approximately 18.3 million tonnes of canola; however, the Canola Council of Canada set a goal of producing 26 million tonnes by the year 2025. One approach to achieve this is the manipulation of plant physiological properties. Assimilates produced through photosynthesis contribute significantly to the growth and development of canola plants by effectively partitioning resources into sink organs. Enhanced resource partitioning represents a novel approach for the improvement of canola for high yield under field conditions. This MSc thesis research was undertaken to investigate i) biomass and resource partitioning, and ii) morphological characteristics of leaf anatomical traits of a diverse set of canola accessions from the Canola Breeding Program at the University of Alberta. The study was conducted across five site years i) West-240 (2021), ii) St. Albert (2022), iii) West-240 (2023), iv) St. Albert (2023), v) CDC-N (2023), and evaluated 168 canola accessions from seven different pedigree groups and two checks (L255PC, 45H33). The major parameters investigated for this study included plant biomass (total biomass, leaf, stem, root, root-shoot ratio), leaf area index, thousand seed weight, seed yield, and anatomical parameters of the adaxial and abaxial leaf surfaces (stomatal density, epidermal cell density, trichome density, and stomatal index), under different climatic conditions.  Results demonstrated that environmental factors exerted significant effect on biomass allocation and yield parameters. Experimental sites had significant effect on all biomass and resource partitioning variables with canola accessions performed differently at different sites. In summary, at CDC-N site, all canola accessions including the checks produced significantly greater biomass (total biomass, leaf dry weight, stem dry weight) i.e. source and higher sink weight (yield, thousand seed weight). Canola at this site also showed significantly lower root/shoot ratio indicating efficient resource allocation towards the above ground biomass and yield.  Several canola accessions outperformed the checks demonstrating superior source activity and efficient resource partitioning; however, same accessions also performed differently at different sites. The West-240 site experienced drought condition in 2021, which impacted the seed yield; therefore, yield at this site was significantly lower than at other sites. Biomass was also lower and root/shoot ratio was higher in this site. Among the anatomical traits, the stomata, which is crucial for gas exchange and water regulation, exhibited significant variation among the different canola pedigree groups. Correlation and regression analyses elucidated strong positive relationships between stomatal density and epidermal cell density, implying that they may have co-evolved. Overall, this study provided valuable insights into the physiological and morphological aspects of the canola leaves, and the knowledge gained from this study can facilitate crop management strategies and help breeding efforts for the development of resilient and productive canola cultivars.</p>