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Euphorbia lagascae is grown because of vernolic acid, an epoxidized fatty acid that has multiple industrial uses. The objective of this thesis was to determine the genetic control of seed germination and seed shattering traits. Five different wild-type genotypes of E. lagascae that demonstrated high germination potential were crossed with an EMS mutant genotype that produces non-shattering capsules. The F2 populations were separated into three different treatments: light, GA3, and control. Consequently, the plants treated with around 250 µmol of light showed improvement in germination up to 75% in cross A and 82.4 % in cross B. The chi-square test indicated that the expression of seed germination, when treated with light, is simply inherited as 3:1 segregation ratio for germinated vs. not germinated seeds, indicating of a single gene with dominance gene action. The same conclusion was reached when phenotyping for the shattering trait for the subpopulations treated with light. OMAFRA-University of Guelph-partnership

In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field.