Seed mass and germination traits relationships among different plant growth forms with aerial seed bank in the sub-tropical arid Arabian deserts (original) (raw)
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Germination strategies of annual and short-lived perennial species in the Arabian Desert
Journal of Arid Land
Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation. In deserts, the spatiotemporal distribution of plant-available water is highly episodic and unpredictable, making winter months more favorable for seed germination when other abiotic conditions co-occur. We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage. We assessed 21 annual and short-lived perennial species in the Arabian Desert to find (1) if seeds were dormant at maturity, (2) if in situ seed storage increased germination percentage compared with no storage, (3) if photoperiod and thermoperiod germination requirements were influenced by in situ storage, and (4) if a phylogenetic association in seed germination could be observed. Seeds of each species collected in early 2017 were divided into two batches. One was tested for germination within one week (fresh seeds). The other was stored in situ at the maternal location (stored seeds) until October 2017 and tested for seed germination in the first week of November. Seed germination was conducted in incubators at two thermoperiods (15°C/20°C and 20°C/30°C; 12 h/12 h), and two photoperiods (12 and 0 h light per day). Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage. A thermoperiod response was exhibited by stored, but not fresh seeds. Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds. Germination traits exhibited no phylogenetic correlation. This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.
Plant Species Biology
The effect of photoperiod, thermoperiod and their interaction on seed germination and its rate was studied for nine grasses growing in the Arabian desert. Germination tests were conducted under two photoperiods and three thermoperiods. Germination of lightincubated seeds of Hyparrhenia hirta, Pennisetum divisum, Stipacapensis, Centropodia forsskaolii, Stipagrostis plumosa, Cymbopogon parkeri and Panicum turgidum was significantly higher than that detected in the darkness. Photoperiod did not influence the seed germination of Aristida adscensionis and Imperata cylindrica. Seeds of all species, except P. divisum, C. parkeri and I. cylindrica, germinated indepen dently of the tested temperature. Our results indicate that species belonging to the same family and growing in the same hyper-arid desert habitat may influence and act in different ways during the seed germination phase, causing species-specific effects, and therefore might affect the ecology of each taxon in this harsh environment.
Seed Germination of selected Taxa from Kachchh Desert, India
The district of Kachchh contains many culturally important plants. However, their conservation status is little known due to direct and indirect human activities. This study was undertaken with the aim of contributing to the conservation of the native species of these semi-arid regions through germination trials under laboratory conditions. Mature fruits of ten selected species were collected randomly from the known habitats to obtain viable seeds. These seeds were pre-treated with growth regulators singly or in combination after acid scarification or without scarification. Seeds were found to be dormant due to presence of thick seed coat or due to low level of endogenous hormonal level. Most of these seeds required different storage period to mature. Only seeds of Capparis cartilaginea germinated without treatment while the other species required treatments. Addition of growth regulators has enhanced seed germination in few taxa singly and in some plant cases in combination.
Journal of Arid Land
Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes. The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production. Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum (Gmel.) Henr. in the desert of Kuwait was evaluated in different populations in May 2017. Experiment of seed germination (25 seeds and 4 replicates) was conducted for each population at night/day temperatures of 15°C/20°C and 20°C/30°C under the following light condition: continuous darkness or 12 h/12 h light/dark. Results showed that seed masses of both species strongly varied according to their seed provenances, and both species produced heavier seeds in population with a higher soil electrical conductivity. Seed germination percentage considerably varied between two species, and the variation in P. turgidum was greater (17%-49%) than that of P. divisum (72%-93%). Germination percentage in P. turgidum was greater at high temperature (20°C/30°C) than at low temperature (15°C/20°C). However, temperature regimes had no effect on germination percentage of P. divisum seeds. Mean germination time of both species exhibited significant inter-population variability. This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species. Besides this, inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.
Abstract Effects of different water potentials on the germination of some desert plants were studied. Water potentials were decreased by using different concentrations of polyethylene glycol 1500 (PEG) and sodium chloride (NaCl). Effects of reduced water potentials on seed germination as well as plumule and radicle elongation were examined at 16 hours light/day and in the continuous darkness. The investigated plant species are: Aizoon canariense L., Convolvulus lanatus Vahl., Artemisia monosperma Del. and Cyperus laevigatus L. Vitality and imbibition of the concerned seeds as affected by different water potentials were tested. Emergence and length of radicle and plumule differed conspicuously among the plant species. The emergence plumules are more sensitive to a reduced water potential than that of the radicle. Generally, the water potential of -1MPa has suppressive effects on the germination and growth parameters of the studied plants.
Dry-storage and light exposure reduce dormancy of Arabian desert legumes more than temperature
Seed Science and Technology, 2020
Propagation and conservation of desert plants are assisted by improved understanding of seed germination ecology. The effects of dry-storage on dormancy and germination were studied in seven desert legumes. Mature seeds were collected in summer 2017 and germinated within one week of collection (fresh) and after six months (dry-storage) under two temperature and two light regimes. Seed weight of two species increased 22-55% within 24 hours of water imbibition but others increased ≤ 7%. Germination ranged from 0-32% in fresh and 2-92% in dry-stored seeds, indicating a mix of non-and physically-dormant seeds at maturity. Dry-storage at ambient room temperature was effective at relieving dormancy, though the extent was species-dependent. Germination percentage increased in response to light exposure during incubation, while the effect of temperature was species-dependent. This variable response to dormancy alleviation may assist to spread the population risk of seedling survival in the harsh and variable environment of the Arabian desert.
Ecology and Evolution, 2015
Our study focuses on the keystone species Acacia tortilis and is the first to investigate the effect of domestic ungulates and aridity on seed viability and germination over an extensive part of the Eastern Sahara. Bruchids infest its seeds and reduce their viability and germination, but ingestion by ruminant herbivores diminishes infestation levels and enhances/promotes seed viability and germination. The degree of these effects seems to be correlated with animal body mass. Significantly reduced numbers of wild ruminant ungulates have increased the potential importance of domestic animals and pastoral nomadism for the functionality of arid North African and Middle Eastern ecosystems. We sampled seeds (16,543) from A. tortilis in eight areas in three regions with different aridity and land use. We tested the effect of geography and sampling context on seed infestation using random effects logistic regressions. We did a randomized and balanced germination experiment including 1193 seeds, treated with different manure. Germination time and rates across geography, sampling context, and infestation status were analyzed using time-to-event analyses, Kaplan-Meier curves and proportional hazards Cox regressions. Bruchid infestation is very high (80%), and the effects of context are significant. Neither partial infestation nor adding manure had a positive effect on germination. There is a strong indication that intact, uningested seeds from acacia populations in the extremely arid Western Desert germinate more slowly and have a higher fraction of hard seeds than in the Eastern Desert and the Red Sea Hills. For ingested seeds in the pastoralist areas we find that intact seeds from goat dung germinate significantly better than those from camel dung. This is contrary to the expected body-mass effect. There is no effect of site or variation in tribal management.
TheScientificWorldJournal, 2014
Seed dispersal and germination were examined for 70 species from the cold Gurbantunggut Desert in northwest China. Mean and range (3 orders of magnitude) of seed mass were smaller and narrower than those in other floras (5-8 orders of magnitude), which implies that selection favors relatively smaller seeds in this desert. We identified five dispersal syndromes (anemochory, zoochory, autochory, barochory, and ombrohydrochory), and anemochorous species were most abundant. Seed mass (F = 3.50, P = 0.01), seed size (F = 8.31, P < 0.01), and seed shape (F = 2.62, P = 0.04) differed significantly among the five dispersal syndromes and barochorous species were significantly smaller and rounder than the others. There were no significant correlations between seed mass (seed weight) (P = 0.15), seed size (P = 0.38), or seed shape (variance) (P = 0.95) and germination percentage. However, germination percentages differed significantly among the dispersal syndromes (F = 3.64, P = 0.01) and s...
AoB PLANTS, 2015
Environmental tolerance of a species has been shown to correlate positively with its geographical range. On the Ordos Plateau, three Caragana species are distributed sequentially along the precipitation gradient. We hypothesized that this geographical distribution pattern is related to environmental tolerances of the three Caragana species during seed germination and seedling emergence stages. To test this hypothesis, we examined seed germination under different temperature, light and water potentials and monitored seedling emergence for seeds buried at eight sand depths and given different amounts of water. Seeds of C. korshinskii germinated to high percentages at 5: 15 to 25: 35 °C in both light and darkness, while those of C. intermedia and C. microphylla did so only at 15: 25 and 25: 35 °C, respectively. Nearly 30% of the C. korshinskii seeds germinated at -1.4 MPa at 20 and 25 °C, while no seeds of the other two species did so. Under the same treatments, seedling emergence perc...
Seed germination traits of desert perennials
Plant Ecology, 2017
While understanding that seed germination is crucial for ecological restoration activities, the seed traits of desert perennials are understudied. We experimentally determined germination traits of 43 species from 14 families from Hummock grasslands in the Great Sandy Desert, Australia. We defined morphological and physiological seed traits of framework species required for restoration and investigated the effects of fire and temperature on seed germination. We classified dormancy and explored the effect of Karrikinolide, a fire cue derived from smoke, on germination. Seeds of 38 (88%) out of 43 species were dormant: 13 (30%) with physical and 25 (58%) with physiological dormancy. Karrikinolide promoted seed germination of 9 (21%) species across all life-forms except trees, and widened the range of germination temperatures and increased germination rate of one species. Although high germination percentages were obtained over a wide temperature range, germination rate was affected by temperature. Non-dormant seeds and seeds pre-treated to overcome physical dormancy germinated quickly, with times to 50% germination of 1-5 days. Dormancy class differed between life-forms and families. Fast germination of non-dormant seeds is a trait that allows seeds to germinate during short periods of moisture availability. An absence of underdeveloped embryos is consistent with the global trends for hot deserts. A response to Karrikinolide shows that seed germination is related to a fire cue. These results will inform land managers of effective seed pretreatments prior to seed broadcasting for restoration, and information on seed germination temperatures and rates will improve the understanding of when and where seeds could germinate in restored sites. Keywords Community assembly Á Dormancy Á Environmental filter Á Karrikinolide Á Plant trait Á Restoration Communicated by Christina Birnbaum.