| Autor: |
Dantas BF; Embrapa Semiárido, Caixa Postal 23, Rodovia BR-428, Km 152, Zona Rural, Petrolina, 56302-970, PE, Brazil. barbara.dantas@embrapa.br., Moura MSB; Embrapa Semiárido, Caixa Postal 23, Rodovia BR-428, Km 152, Zona Rural, Petrolina, 56302-970, PE, Brazil., Pelacani CR; Universidade Estadual de Feira de Santana- UEFS, Feira de Santana, BA, Brazil., Angelotti F; Embrapa Semiárido, Caixa Postal 23, Rodovia BR-428, Km 152, Zona Rural, Petrolina, 56302-970, PE, Brazil., Taura TA; Embrapa Semiárido, Caixa Postal 23, Rodovia BR-428, Km 152, Zona Rural, Petrolina, 56302-970, PE, Brazil., Oliveira GM; Universidade Estadual de Feira de Santana- UEFS, Feira de Santana, BA, Brazil., Bispo JS; Universidade do Estado da Bahia- UNEB, Juazeiro, BA, Brazil., Matias JR; Universidade Federal Rural do Semiárido- UFERSA, Mossoró, RN, Brazil., Silva FFS; Universidade Estadual de Feira de Santana- UEFS, Feira de Santana, BA, Brazil., Pritchard HW; Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, UK., Seal CE; Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, UK. |
| Abstrakt: |
Drylands are predicted to become more arid and saline due to increasing global temperature and drought. Although species from the Caatinga, a Brazilian tropical dry forest, are tolerant to these conditions, the capacity for germination to withstand extreme soil temperature and water deficit associated with climate change remains to be quantified. We aimed to evaluate how germination will be affected under future climate change scenarios of limited water and increased temperature. Seeds of three species were germinated at different temperatures and osmotic potentials. Thermal time and hydrotime model parameters were established and thresholds for germination calculated. Germination performance in 2055 was predicted, by combining temperature and osmotic/salt stress thresholds, considering soil temperature and moisture following rainfall events. The most pessimistic climate scenario predicts an increase of 3.9 °C in soil temperature and 30% decrease in rainfall. Under this scenario, soil temperature is never lower than the minimum and seldomly higher than maximum temperature thresholds for germination. As long as the soil moisture (0.139 cm 3 cm 3 ) requirements are met, germination can be achieved in 1 day. According to the base water potential and soil characteristics, the minimum weekly rainfall for germination is estimated to be 17.5 mm. Currently, the required minimum rainfall occurs in 14 weeks of the year but will be reduced to 4 weeks by 2055. This may not be sufficient for seedling recruitment of some species in the natural environment. Thus, in future climate scenarios, rainfall rather than temperature will be extremely limiting for seed germination. |
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