Maternal salinity environment affects salt tolerance during germination in Anabasis setifera： A facultative desert halophyte

The effects of maternal salinity and light incubation on the salinity tolerance of the facultative halophyte Anabasis setifera during their germination stages were assessed. Seeds were collected from non-saline habitats in Egypt and saline habitats in the United Arab Emirates （UAE）. The seeds of the two populations were germinated in 0, 100, 200, 400, 600 and 800 mM NaCI, and incubated at 25℃/15℃ in both 12-h light and 12-h darkness regimes and continuous darkness. Significantly more seeds germinated in the Egyptian population than in the UAE population. Salinity tolerance was significantly greater with the Egyptian population than with the UAE population, especially under the conditions of higher salinities. The difference in salinity tolerance between the seeds of two populations was attributed to their seed mass. In addition, germination was significantly faster for the Egyptian population than for the UAE population. Most of the saline treated seeds were able to recover their germination when transferred to distilled water, but this depended on their maternal salinity and light incubation. Recovery from higher salinities was significantly better for the seeds under darkness than for those under light in the UAE population, but the reverse was true for the seeds in the Egyptian population. The higher salinity tolerance for the A. setifera seeds from the non-saline Egyptian population and the lower salinity tolerance for the seeds from the saline UAE population cannot explain their natural distribution. Further studies about other possible roles, such as levels of different promoting and inhibiting phytohormones, are needed to understand the importance of salinity as an environmentally induced maternal effect.

Evaluating germinability of eight desert halophytes under long-term seed storage: Implications for conservation

Ex situ conservation in seed banks is a potential complementary conservation strategy for native plant species.It is well established that ex situ seed banking of native wild plants prolongs seed viability and thereby preserves genetic and species diversity for future use.We evaluated ex situ storage potential of eight halophytic species from deserts in the United Arab Emirates(UAE)by studying seed germination.Specifically,we examined the germinability of freshly collected seeds and seeds stored for three years in a seed bank.We also examined the effect of light conditions on fresh and stored seed germination.Fresh seeds of seven of the eight species tested had a higher germination rates under 12/12 h light/dark fluctuations than did those exposed to total darkness.Storage reduced light sensitivity in Halocnemum strobilaceum,Suaeda aegyptiaca,Salsola drummondii and Salsola imbricata,but increased the requirement for light in Arthrocnemum macrostachyum.In Anabasis setifera,storage decreased germination percentage when there was a 12-hour light/dark fluctuation,but increased germination rate when exposed to the dark treatment.Storage significantly reduced germination in both the light/dark and dark treatments in Suaeda vermiculata and S.aegyptiaca.Germination speed also responded differently to storage;whereas Timson's index significantly increased in A.macrostachyum and H.strobilaceum,it significantly decreased for S.drummondii,S.aegyptiaca and S.vermiculata.Germination of these species at a range of temperatures requires further testing;additionally,we strongly suggest that these laboratory findings be complemented by field studies.

Delayed seed dispersal species and related traits in the desert of the United Arab Emirates

The ability of plants to safely retain seeds in the mother plant is an adaptive mechanism described in many desert plants.However,research about delayed seed dispersal species in the desert of the United Arab Emirates(UAE)is lacking.This study aims to identify these delayed seed dispersal species and assess the relationships of the presence of delayed seed dispersal with plant growth form,habit,spatial dispersal,antitelechoric mechanism,and seed release time.The relationships between the presence of delayed seed dispersal and the above studied traits were assessed by using the Pearson Chi-square test and Nonlinear Principal Components Analysis(NLPCA).Results showed that a total of 46 delayed seed dispersal species were recorded(15.0%of 307 studied species)and the highest incidence occurred in the Fabaceae family(17.4%).Delayed seed dispersal species were predominantly perennial plants(73.9%)with spatial restricted dispersal(67.4%),which released seed in the dry season(45.7%).The dominant groups of delayed seed dispersal species were persistent fruits species and synaptospermy(28.3%).All graminoids showed persistent lignified fruits,while prostrate annuals were basicarpic species with myxospermy.Sandy habitats had the highest number of delayed seed dispersal species(54.3%),whereas salt flats had the lowest(23.9%).In the desert of the UAE,delayed seed dispersal species spread seeds until the end of the dry and windy season,thus breaking seed dormancy at this time and ensuring seed germination in the next arrival of the rainy season.This morphological and ecological adaptation of delayed dispersal species is essential to the survival and sustainable development of vegetation in desert environments.