Germination sensitivities to water potential among co - existing C3 and C4 grasses of cool semi-arid prairie grasslands
An untested theory states that C4 grass seeds could germinate under lower water potentials [?] than C3 grass seeds. We used hydrotime modelling to study seed water relations of C4 and C3 Canadian prairie grasses to address ? divergent sensitivities and germination strategies along a risk-spreading continuum of responses to limited water. C4 grasses were Bouteloua gracilis, Calamovilfa longifolia and Schizachyrium scoparium; C3 grasses were Bromus carinatus, Elymus trachycaulus, Festuca hallii and Koeleria macrantha. Hydrotime parameters were obtained after incubation of non-dormant seeds under different ? PEG 6000 solutions. A t-test between C3 and C4 grasses did not find statistical differences in population mean base ? [?b[50]]. We found idiosyncratic responses of C4 grasses along the risk-spreading continuum. B. gracilis showed a risk-taker strategy of a species able to quickly germinate in a dry soil due to its low ?b[50] and hydrotime [?H]. The high ?b[50] of S. scoparium indicates it follows the risk-averse strategy so it can only germinate in wet soils. C. longifolia showed an intermediate strategy: the lowest ?b[50] yet the highest ?H. K. macrantha, a C3 grass which thrives in dry habitats, had the highest ?b[50], suggesting a risk-averse strategy for a C3 species. Other C3 species showed intermediate germination patterns in response to ? relative to C4 species. Our results indicate that grasses display germination sensitivities to ? across the risk-spreading continuum of responses. Thus seed water relations may be poor predictors to explain differential recruitment and distribution of C3 and C4 grasses in the Canadian prairies.
| Main Authors: | , |
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| Format: | Texto biblioteca |
| Language: | spa |
| Subjects: | WATER AVAILABILITY, SOIL WATER AVAILABILITY, SOIL WATER, SEMIARID REGION, SEMI-ARID GRASSLANDS, SCHIZACHYRIUM SCOPARIUM, RECRUITMENT [POPULATION DYNAMICS], RECRUITMENT, PRAIRIE, POACEAE, KOELERIA MACRANTHA, GRASS, GERMINATION ECOLOGY, GERMINATION, FESTUCA HALLII, ELYMUS TRACHYCAULUS, COEXISTENCE, CANADA, CALAMOVILFA LONGIFOLIA, C4 PLANT, C4 GRASSES, C3 PLANT, C3 GRASSES, BROMUS CARINATUS, BOUTELOUA GRACILIS, , |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=47213 http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber= |
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