Effects of temperature, salinity and cold stratification on seed germination in halophytes

Abstract

Salt tolerance of halophytes corresponds with the habitat requirement of the species. It is an important factor during the germination phase and it can determine successful establishment. This paper presents the effects of alternating temperaturelight regimes (4/8°C, 10/20°C, 20/32°C; 12 h dark: 12 h light) and different salinity levels (0, 200, 400, 600 mmol l 21 NaCl) on seed germination of five halophytes, Halimione pedunculata, Bupleurum tenuissimum, Aster tripolium, Triglochin maritimum and Armeria maritima. The five species differ with respect to family and life-form and spatially correspond to a decreasing salt gradient (i.e. distance from salt water, with H. pedunculata being the most tolerant and A. maritima being the least). Armeria maritima, A. tripolium and T. maritimum seeds were additionally subjected to a cold stratification experiment. The results showed that Halimione pedunculata, an annual therophyte of year-round heavily saline habitats, was dormant under all experimental conditions. Bupleurum tenuissimum, a species typical to sites of varying salinity prone to leaching during spring and autumn rainfall, germinated best under cold and warm temperatures, but only under non-saline conditions. Aster tripolium and T. maritimum, close neighbours in salt marshes, showed very similar germination behaviour: seeds of both species tolerated high levels of salinity and germinated best in summer temperatures during periods of highest soil salinity, and germination was significantly promoted by cold. Armeria maritima, a species usually found on the marginal fringes of saline habitats, germinated only under low salt levels and maximum germination was under cold (spring) and warm (autumn) temperatures, with no significant effect of cold stratification.

Salt Induces Features of a Dormancy-Like State in Seeds of Eutrema (Thellungiella) salsugineum, a Halophytic Relative of Arabidopsis

“…In this report, we have used the halophytic Arabidopsis relative, E. salsugineum to identify biochemical alterations and dormancy-associated gene expression changes underlying the widespread phenomenon of salt-mediated inhibition of halophyte seed germination ( Ungar, 1978 ; Gulzar and Khan, 2001 ; Song et al, 2005 ; Qu et al, 2008 ; Orsini et al, 2010 ; Al-Hawija et al, 2012 ; Cao et al, 2012 ; Gul et al, 2013 ). It had been previously reported that E. salsugineum seed germination is inhibited by salt ( Inan et al, 2004 ; Orsini et al, 2010 ), and we further extended these findings to show that E. salsugineum seeds respond to as low as 50 mM NaCl, which causes a delay in germination ( Figure 1A ).…”

“…Furthermore, seeds in the seed bank can undergo seasonal cycling between physiologically dormant and non-dormant states ( Baskin and Baskin, 1998 ; Cadman et al, 2006 ; Footitt et al, 2011 ; Penfield and Springthorpe, 2012 ; Ibarra et al, 2015 ). One major environmental factor affecting germination of halophytes is the concentration of salt in the soil, and it has been known for decades that seeds of a large number of halophytes will not germinate on high levels of salt ( Ungar, 1978 ; Gulzar and Khan, 2001 ; Khan et al, 2003 ; Song et al, 2005 ; Qu et al, 2008 ; Orsini et al, 2010 ; Al-Hawija et al, 2012 ; Cao et al, 2012 , 2014 ; Gul et al, 2013 ). Although the reduction in seed germination rates and percentages of halophytes in response to salt has been well-documented, there has been no systematic investigation of the biochemical and gene expression changes occuring in halophytic seeds during salt-mediated inhibition of germination.…”

Effect of salinity on seed germination and seedling growth of the halophyte Suaeda japonica Makino

“…300‐mM NaCl) has been reported as 4°C–8°C for Armeria maritima (Al‐Hawija et al . ), 5°C–25°C for Atriplex prostrata and Salicornia europaea (Egan & Unger ), 10°C–20°C for Limonium cossonianum (Luque et al . ) and L. tabernense (Fernández et al .…”

“…), 20°C–32°C for Aster tripolium and Triglochin maritimum (Al‐Hawija et al . ), 25°C for Chloris virgata (Zhang et al . , ), 25°C–35°C for Salsola iberica (Khan et al .…”

Effects of Different Treatments on Physiological Characteristics of <i>Cephalotaxus sinensis</i> Seeds

“…Recently, cold stratification has been widely used to break seed dormancy and enhance the germination percentage. In A. tripolium, the germination of seeds under cold treatment was obvious higher than that without stratification [20]. Also, Lohengrin et al [21] indicated that seed germination with stratification increased significantly.…”