In this study, salt tolerance during germination of Aeluropus lagopoides (L.) Trin. was tested using fresh seeds collected from three different maternal habitats under three thermoperiods and two light regimes. Additionally, we tested the ability of non-germinated seeds that had been exposed to different concentrations of NaCl to recover their germination in distilled water. The results showed a significant effect of seed source, temperature, and salinity, and some of their two- and three-way interactions on final germination and recovery percentage. The seeds from non-saline provenances had the highest percentages for germination (ca. 79%) under the 35/25 °C temperature regime, whereas the lowest percentages for germination (ca. 21%) was recorded for seeds from saline conditions under the 25/15 °C treatment. Additionally, percent germination was significantly lower for the seeds incubated in the saline solutions (100, 200, 400, and 600 mmol/L NaCl) and germinated under colder conditions (15/25 °C), compared with the seeds incubated in non-saline solutions (control group, 0 mmol/L NaCl) and germinated under warmer conditions (35/25 °C). The highest recovery percentage was recorded for seeds of the hyper-saline habitat incubated at 35/25 °C. Thus, seeds maintained their viability despite experiencing a range of saline conditions and were able to germinate upon the arrival of suitable conditions, which can be an adaptation to its saline arid desert habitat.

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.

Light and growth promoting compounds, such as gibberellic acids (GA₃), are among the most important factors that can break physiological seed dormancy. Here, we investigate the effects of GA₃ and light on germination of five species of Resedaceae that are known to have different levels of physiological dormancy. Seeds were incubated at 20/30 °C in both 12hr photoperiod and in complete darkness. To study the effect of growth hormone on germination, seeds were soaked for 24 h in different concentrations of GA₃ before sowing. The annuals (Reseda aucheri and Oligomeris linifolia) and the perennial Ochradenus arabicus had deep physiological dormancy and exogenous application of GA₃ enhanced their germination in the light, but not in darkness; few or no seeds germinated in the dark in these species. Ochradenus aucheri and O. baccatus had intermediate and non-deep dormancy, respectively and application of GA₃ enhanced their germination in both light and darkness. Germination of the annual species was much slower than that of the shrubby perennials. Overall, these results indicate that conditions under which seed developed, matured and stored on maternal plants as well as incubation conditions should be taken into consideration when assessing germination behaviour of the perennial species of Resedaceae.

In many species, seeds with different sizes show diverse responses in their requirements for temperature and light for optimal germination. In this study, the effect of seed size (i.e., small and large) on germination was tested in seeds of Brassica tournefortii Gouan, Lotus garcinii DC., and Salvadora persica L. from arid Arabian Desert habitats. The mean seed size of all three study species differs significantly between small and large-sized seeds. Differences were observed in seed germination between large and small seeds of B. tournefortii and L. garcinii. We found that the large seeds of B. tournefortii and L. garcinii showed a higher germination percentage at all tested temperatures than that displayed by the small seeds. However, both small and large seeds of S. persica germinated equally (100%) well under all tested incubation conditions. Our results show significant differences in germination percentage between the small and large seeds of B. tournefortii at 25/35 °C under a 12 h light regime. However, seeds of L. garcinii showed a significant difference in germination percentage at low temperatures (15/25 °C) under a 12 h light regime.

Field studies of the distribution and ecology of endemic species are fundamental for conservation planning. Schweinfurthia imbricata A.G.Mill., M.Short & D.A.Sutton is a scarce regional endemic found in the Hajar Mountains of the United Arab Emirates (UAE) and Northern Oman, and their periphery. Based on recent fieldwork by the Sharjah Seed Bank and Herbarium (SSBH) and literature data, this paper presents the first detailed account of the distribution, habitat preferences and phenology of S. imbricata in the UAE. Among other things, our fieldwork indicates that S. imbricata is more common and widespread in the UAE than has previously been recognized, including at least 19 heretofore unpublished localities, all hosting multiple individual plants. The implications of our findings for the conservation status of S. imbricata in the UAE are briefly discussed.