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Land degradation is one of the most important environmental problems worldwide, including in the Arabian Peninsula. In arid climatic conditions (i.e., high temperature, high evaporation, scanty rainfall and high salinity), anthropogenic factors (i.e., grazing, camping, infrastructure development, etc.) are the major causes of land degradation. Therefore, restoration of degraded lands is urgently needed to achieve sustainable development goals. Moreover, countries in the Arabian Peninsula are suffering from a lack of natural freshwater resources. Therefore, using halophytes could be an environmentally and economically viable option to overcome limited availability of fresh water by substituting the demand of portable water for irrigation as well as restoring salt-affected lands. Saline soils are common in the Arabian Peninsula, therefore, exploring the ecological and economic potential of halophytes and incorporating them in restoration projects could be a sustainable option. In this study, an attempt was made to document the uses of Arabian halophytes through a survey of the literature and prioritizing them based on their use value. Out of the 107 species studied, 4 species, namely Arthrocnemum macrostachyum (Moric.) K.Koch., Alhagi graecorum Boiss., Bassia muricata (L.) Asch. and Phragmites australis (Cav.) Trin. Ex Steud., were categorized as high priority followed by 36 species under moderate priority. However, when the priority and life form of species was considered for prioritization, three species, namely Alhagi graecorum, Arundo donax L. and Phragmites australis, ranked at the top in the priority list among perennials and Bassia muricata ranked at the top among annuals. This information could be useful for land restoration specialists to use appropriate halophyte species to achieve for different restoration objectives in salt-affected lands. However, there is a need to develop an active monitoring system that strictly concentrates on the recycling of plants that are used in phytoremediation. [ABSTRACT FROM AUTHOR]

Haloxylon salicornicum (Moq.) Bunge ex Boiss. is a suitable species for desert and coastal restoration for its forage production and dune stabilization. Inter-population variation of seed parameters has previously received little attention. Variation in seed germination response to drought and salinity stress was evaluated for three Kuwaiti populations for use in restoration projects. Germination parameters varied significantly among populations. Seeds from Kabd were larger and germinated at a higher percentage than the other two populations, Mutla and Liya, under conditions of saline (62.8%, 40.0%, and 50.7% respectively) and moisture (58.2%, 32.6%, and 45.6%) stress. Increasing salinity and drought simulation progressively inhibited seed germination across all populations. Drought simulation by PEG 6000 inhibited germination from −0.3 MPa, while salinity affected the germination proportion from 400 mM NaCl for all the studied populations. All populations exhibited a high recovery from NaCl and PEG stress, indicating the species is broadly adapted to survival through drought and saline conditions. Our findings indicate that revegetation success with this species will be influenced by the population characteristics of the maternal seed source. [ABSTRACT FROM AUTHOR]

Regeneration of native species is the first priority for biodiversity conservation and restoration. To this end, it is key to have seeds properly conserved in seed banks and knowledge of seed longevity and (or) dormancy alleviation at different storage time intervals. In addition, understanding the germination response of the stored seeds to environmental conditions improves the efficiency of restoration and rehabilitation projects. We investigated the influence of storage duration (1–5 years), light (0 or 12 h of illumination), thermoperiod (night/day temperatures of 15/20 and 20/25 °C), and salinity (0, 100, 200. and 400 mmol/L of NaCl) on seed germination of Rhanterium epapposum, a glycophytic species from the Arabian Peninsula. Seeds maintained viability after five years of storage indoors at room temperature. Three years of storage alleviated seed dormancy. Exposure to 12 h light per day and thermoperiods of 15/20 °C enhanced seed germination. The seeds were glycophytic; after-ripened seeds exposed to salinity exhibited reduced rates of germination that did not recover after the salinity was alleviated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Seed viability and germination are key factors in the success of restoration efforts, especially when stored seeds are used. However, the effect of seed storage on germination of most of the native Arabian species is not well documented. We investigated the effect of storage time and role of the seed mucilage in regulating germination, dormancy, salinity tolerance and consequential survival strategy of F. aegyptia in an unpredictable arid desert setting. Effect of light and temperature during germination was studied under two photoperiods and two thermoperiods using intact and de-mucilaged seeds. Presence of mucilage and thermoperiod did not affect the germination. However, seed collection year and photoperiod had a highly significant effect on the germination. Increasing salinity levels decreased the germination of F. aegyptia but ungerminated seeds were able to germinate when salinity stress was alleviated. Seed storage at room temperature enhances the germination percentage, indicating that F. aegyptia seeds have physiological dormancy and it can be alleviated by after-ripening at dry storage. In addition, F. aegyptia seeds show ability to germinate at lower salinity concentration and remain viable even at higher saline conditions, indicating their adaptability to cope with such harsh environmental conditions. [ABSTRACT FROM AUTHOR]

Suaeda aegyptiaca is a facultative halophyte found in saline and non-saline habitats of the Arab Gulf desert, which produces small-sized undispersible seeds. The interactive effects of maternal salinity and other environmental conditions, such as salinity, light and temperatures, that are prevailing during seed germination have received little attention for a facultative halophyte. This study tested the effects of maternal salinity on salt tolerance during seed germination of S. aegyptiaca under different light and temperature regimes. Seeds collected from both saline and non-saline habitats of the United Arab Emirates ( UAE) were germinated in 0, 50, 100, 200 and 400 mM NaCl, and incubated at 15/25°C, 20/30°C and 25/35°C in both 12-h light/12-h dark regimes and continuous darkness. Generally, seeds of the non-saline habitat were 56% heavier and attained greater germination at the lower temperatures than seeds of the saline habitat. Seeds of the saline habitat germinated better in saline solutions at higher temperatures and in light. Germination was faster for seeds of the saline habitat than for seeds of non-saline habitats. Germination recovery after transfer to distilled water was significantly greater for seeds from the non-saline habitat, compared with seeds from saline habitats. Recovery was greater at lower and/or moderate temperatures, compared with at higher temperatures. Germination was significantly faster during recovery, compared with in the saline solutions. The study indicates that the maternal effect of salinity was confounded with the seed-size effect and it cannot be conclusively confirmed. [ABSTRACT FROM AUTHOR]

Ochradenus baccatus is a perennial glycophyte growing in Middle East and it is one of the most important food sources for many animal species in desert regions. The aim of our study was to investigate the effects of seed storage, light, temperature and gibberellic acid (GA3) on germination of O. baccatus seeds. We also investigated the germination characteristics of O. baccatus seeds under different saline concentration and their capability to recover germination once they were transferred to distilled water. Seeds were stored at room temperature (20 ± 2 °C) and at -18 °C. Germination tests were conducted at alternating temperatures of 15/25, 20/30 and 25/35 °C in either continuous darkness or photoperiod of 12-h dark/12-h light. To study the effect of GA3 on germination of O. baccatus seeds, freshly-collected seeds and stored seeds were soaked for 24 h in a GA3 water solution (1 g/L) before sowing. To assess the salinity tolerance during germination, seeds were germinated under different salinity levels (100, 200 and 400 mM NaCl). Stored seeds at room temperature and -18 °C germinate equally well at different temperature regimes and light conditions. However, freshly matured seeds were not able to germinate even when they were treated with GA3. On the contrary, stored seeds at room temperature and -18 °C treated with GA3 increase the final germination percentages. These results indicated that O. baccatus seeds have physiological dormancy and they need to be stored in order to break their dormancy. In the present study, one year of storage did not show a significant variation in germination between the two storage conditions assayed. Therefore, further research is needed to know about the maximum storage period for O. baccatus seeds under different storage conditions. Very few O. baccatus seeds (less than 5%) germinated at the tested lowest concentration of NaCl. However, ungerminated seeds were able to germinate when salinity stress was alleviated. In conclusion, O. baccatus seeds have physiological dormancy, and seed storage (at room temperature and at -18 °C) for one year is effective for breaking this dormancy. In addition, O. baccatus seeds present ability to remain viable in saline conditions and they will be able to germinate once the salinity level decrease. Rev. Biol. Trop. 64 (3): 965-974. Epub 2016 September 01. [ABSTRACT FROM AUTHOR]

Rehabilitation of coastal vegetation is reliant on the successful establishment of halophytic seedlings. Seed germination variation among populations of two desert halophytes, Arthrocnemum macrostachyum and Suaeda vermiculata , was assessed under seven salinity levels from 0 to 1,000 mM NaCl. recovery of germination in seeds previously exposed to salinity stress was also assessed. Correlation between seed fresh weight and germination was strongly positive in S. vermiculata (r = 0.852; P = 0.007), and moderate in A. macrostachyum (r = 0.547; P = 0.066). Seed germination of A. macrostachyum increased in similar proportion to a decline in the mean germination time (MGT) in a weak but significant correlation (r = 0.492; P = 2.4 × 10−3). Similarly, the decline of MGT was associated with a decline of germination synchrony (SYN; r = 0.551; P = 9.7 × 10−4). Increased germination of S. vermiculata seeds was not associated with any change in MGT (P value = 0.078), but showed a significant increase in SYN (r = 0.851; P = 1.1 × 10−5). A similar pattern was found between SYN and MGT which shows a strong positive correlation (r = 0.687; P = 6.7 × 10−4). Seed germination of S. vermiculata appears to be strongly influenced by provenance, but the relationship in A. macrostachyum is less clear. The lower soil pH also promoted the seed germination with consequent a decrease of mean germination time (MGT). Efficiency of coastal restoration projects can be improved by selecting natural seed sources from locations and/or seasons producing above-average seed weight. • Seeds of both species recovered their germinability after alleviating salinity stress. • The ability recover germinability varies according to the population. • A macrostachyum seeds did not show interpopulation difference in germination recovery. • S. vermiculata seeds showed significant variation of germination recovery. • Data shows that seed source plays an important role in determining the germination. [ABSTRACT FROM AUTHOR]