PARENT SESSION
Contributed Oral Session 156: Grassland Resource Allocation, Dispersal, and Pollination
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 516 C, Level 5, Palais des congrès de Montréal
Heteromorphic seed production in populations of Punagrass, a perennial grass with mixed mating system.
Lerner, Pamela*,1, 2, Bai, Yuguang1, 1 University of Saskatchewan, Saskatoon, Saskatchewan, Canada2 Universidad Nacional de La Pampa, Santa Rosa, La Pampa, Argentina
ABSTRACT- Species or populations that have been historically subjected to high frequencies and intensities of disturbances can have adaptations to these disturbances, including their reproductive strategies. Such populations often have a short juvenile period, or show a 'pessimistic' strategy of producing locally adapted progeny early and larger numbers of potentially more variable progeny later. Punagrass (Achnatherum brachychaetum (Godr.) Barkworth) is a cool-season, mid-height invasive grass from South America that produces heteromorphic seeds from chasmogamous (CH) and cleistogamous (CL) flowers. We studied reproductive phenology, and seed production of plants derived from CH and CL flowers from overgrazed (poor condition, PG) and adequately grazed grassland areas (good condition, GG) of central Argentina in a greenhouse experiment. CL seeds were produced earlier than CH seeds. CH flowers were first developed by CL derived plants. The number of tillers with CH seeds was higher in GG than PG (p < 0.05). There were not significant differences in CL, CH, and total seed production between CH and CL derived plants. Total seed production and CH seed production were highly variable, being more variable for plants from GG, while the variability of CL seed production was low in both areas. Plants from GG produced higher CL seed number (p <0.05) and total CL seed mass per plant than PG (p < 0.05). It is suggested that the mating system may influence the timing of development, and the ecological history the variability of CH seed production, while that CL seed production would be genetically determined by local adaptation.
Key words: cleistogamy, chasmogamy, grazing, Achnatherum brachychaetum