Abstract
Abstract: Myracrodruon urundeuva, a native species from the Brazilian Caatinga, is widely distributed across its endemic region, where it also plays an essential socioeconomic role. The objective of this study was to evaluate the influence of environmental stress on the germination of M. urundeuva seeds harvested in different years (2010 to 2013). Seeds were germinated at constant temperatures between 10 to 40 °C, osmotic potentials from 0 to -0.8 MPa (in polyethylene glycol 6000 solutions), and from 0 to -0.5 MPa (in NaCl solutions). The experiment was conducted according to a completely randomized design, with three replicates of 50 seeds, in a factorial scheme (harvest year x stress intensity) for each environmental stress. Germination data were then analysed using thermal, hydro and halo time models, and future germination responses projected according to climate change scenarios. The germination thermal thresholds ranged from 7.4 to 53.3 oC. The germination base osmotic threshold (using polyethylene glycol) was -0.6 MPa and the base osmotic threshold in NaCl was -0.43MPa. Seeds from different harvest years showed distinct tolerance to environmental stresses. The thermal, hydro and halo-time models were efficient to describe the germinative response of seeds, and the climate models allowed to identify the germination responses of M. urundeuva in future climate. According to the models for future climate (RCP 8.5), the reduction of rainfall by 2100 will directly affect seed germination and seedling recruitment of M. urundeuva.
Highlights
Climate projections published in the Fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) indicate increasing emission of greenhouse gases (GHG) as the primary cause for temperature changes
Future climate scenarios include a increase of the average global temperature and a decrease in the precipitation levels (IPCC, 2014), which can alter the salinity of the soil (Knowles and Cayan, 2002; Gondim et al, 2010)
Myracrodruon urundeuva seeds are tolerant to a broad range of temperatures and osmotic potentials
Summary
Climate projections published in the Fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) indicate increasing emission of greenhouse gases (GHG) as the primary cause for temperature changes. Future climate scenarios include a increase of the average global temperature and a decrease in the precipitation levels (IPCC, 2014), which can alter the salinity of the soil (Knowles and Cayan, 2002; Gondim et al, 2010). Climate change may have important consequences to all stages of plant development, from seed germination to growth and establishment of species (Maraghni et al, 2010). Germination is an ecophysiological process fundamental to plant diversity (Bewley et al, 2013), which depends on the environmental conditions to which seeds are subjected to. The capacity of seeds for germinating in a broad variety of conditions assures the survival and regeneration of species (Vivian et al, 2008)
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