Journal
AMERICAN JOURNAL OF BOTANY
Volume 109, Issue 12, Pages 2018-2029Publisher
WILEY
DOI: 10.1002/ajb2.16088
Keywords
Cerrado; climate change; dry grasslands; germination; Graminae; grasses; Poaceae; temperature; water stress; wet grasslands
Categories
Funding
- Conselho Nacional de Desenvolvinento Cientifico e Tecnologico - CNPq, Brazil [312152/2018-3, 130924/2017-2]
- Fundacao de Apoio a Pesquisa do Distrito Federal [193.000/230-2014]
- Fundacao de Apoio a Pesquisa de Sao Paulo - FAPESP, Brazil [2017/17380-1]
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This study examined the response of seeds from dry and wet grassland grasses to water stress under current and future temperature conditions. The results showed that increasing water stress reduced the viability of grass seeds, and the future temperature conditions reduced the viability of wet grassland species and altered the germination strategy of dry grassland species.
PremiseSeed germination is controlled by the soil microclimate, which is expected to change with the temperature increase and rainfall irregularity predicted for the future. Because changes in soil characteristics directly affect species recruitment, vegetation dynamics and resilience, we investigated how caryopses of native grasses from dry and wet grasslands respond to water stress under current and future temperature regimes. MethodsCaryopses were collected from 10 grass species in dry and wet grasslands, subjected or not to a fire event, and tested for germination at increasing osmotic potential (0 to -1.0 MPa) at current (17 degrees/27 degrees C night/day) and future (23 degrees/33 degrees C) simulated temperatures. ResultsThe viability and germination percentages of caryopses from both dry and wet grassland species were progressively reduced as osmotic stress increased, irrespective of temperature regime. The viability of caryopses from wet grassland species was reduced under the future temperature regime, irrespective of osmotic potential. The slow germination of caryopses of dry grassland species at the present temperature regime was absent when they were incubated in the future temperature regime. ConclusionsMore intense water stress reduced the survival of caryopses for both dry and wet grassland grass species. The predicted future temperature regime reduced the viability of wet grassland species and altered the germination strategy of dry grassland species. These results indicate that increasing water stress and temperature predicted for the future may compromise the recruitment potential of dry and wet grassland species and directly impact the dynamics and resilience of these ecosystems.
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