Influence of priming on Eucalyptus spp seeds' tolerance to salt stress

Abstract

-The objective of this experiment was to evaluate the effect of priming on the germination of Eucalyptus urophylla and of hybrid E. urophylla × E. grandis seeds under salt stress. Two osmotic potentials (-1.0 and -1.5 MPa) were tested, using PEG 6000 for 1 and 3 days. After priming, seeds were germinated under salt stress in a NaCl solution at 0.0 (control), -0.5, -0.75 and -1.0 MPa potentials, at 25 °C. Seed germination and germination speed index decreased as the water potential of the germination medium decreased. However, E. urophylla was more tolerant to salt stress; it showed a higher germination percentage under all tested potentials, when compared to the hybrid. The osmotic conditioning at -1.0 MPa for three days was more effective when E. urophylla x E. grandis was germinated in a salt solution at -1.0 MPa, indicating that this treatment was more effective in inducing tolerance to salt stress.

Micromorphological Observation of Eucalyptus Seeds, Multivariate Statistical Analyses and Modeling of Their Germination Under Salt Stress and Osmotic Constraint

“…Similar results obtained by José et al (2016) who showed that under salt stress, germination continuously decreased, reaching 39% and 13% at -1.0 MPa for E. urophylla and E. urophylla x E. grandis, respectively. Seed germination and germination speed index decreased as the water potential of the germination medium decreased (José et al, 2016). However, E. urophylla was more tolerant to salt stress; it showed a higher germination percentage under all tested potentials, when compared to the E. urophylla x E. grandis.…”

“…The five Eucalyptus species were able to germinate at up to -1 MPa (19 to 72 %) with a notable rate of Eucalyptus gomphocephala x Eucalyptus cornuta (61%) at -1.6 MPa NaCl. For the hybrid, this germination solution potential caused a marked drop in the germination final percentage from 77% at -0.5 MPa to 35% at -0.75 MPa (José et al, 2016). The germination of E. urophylla drastically decreased only when seeds were placed under -1.0 MPa salt stress.…”

“…The largest tolerance of salinity of the Eucalyptus saligna can be due to the larger produced amount of sugar soluble and proline (Lopes da Silva et al, 2012). The osmotic conditioning in PEG enabled an increase in the final germination speed and percentage under salt stress for both species (José et al, 2016). The five Eucalyptus species were able to germinate at up to -1 MPa (19 to 72 %) with a notable rate of Eucalyptus gomphocephala x Eucalyptus cornuta (61%) at -1.6 MPa NaCl.…”

“…However, E. urophylla was more tolerant to salt stress; it showed a higher germination percentage under all tested potentials, when compared to the E. urophylla x E. grandis. José et al (2016) showed that a low germination rate (0%) was detected on Eucalyptus gillii in 15 g . L -1 .…”

Water stress in germination, growth and development of coffee cultivars

“…Thus, in the control treatment, each cultivar exhibited a different pattern of germination, while under water stress, the seeds had standardization of the responses. In this case, standardization of germination suggests some relationship to osmoconditioning or priming, a process that may be induced by the PEG, which is used to optimize and synchronize responses of seeds that have difficulties in germination (Dantas et al, 2010;José et al, 2016). Abdel-Ghani et al (2015) also found that barley seeds had osmoconditioning responses when exposed to 15% and 18% PEG 6000, through achieving a higher rate of germination than those of the control.…”