Seed Germination Strategies Research Articles

Adaptive Seedling Strategies in Seasonally Dry Tropical Forests: A Comparative Study of Six Tree Species.

This study examines seed germination strategies and seedling establishment in six tree species typical of seasonally dry tropical forests. We focused on how interspecific and intraspecific differences in seed size and germination speed influence biomass allocation and seedling growth. Using generalized linear models, we analyzed the effects of these traits on root/shoot ratios and growth rates. Our findings reveal two main strategies: slow germination, high root/shoot ratio, and low growth rate in Erythrina velutina Willd and Terminalia valverdeae A.H. Gentry, associated with enhanced drought tolerance. In contrast, Cynophalla mollis (Kunth) J. Presl and Coccoloba ruiziana Lindau exhibited rapid germination, lower root/shoot ratios, and low to moderate growth rates, favoring competition during early establishment. Centrolobium ochroxylum Rose ex Rudd partially aligned with this second strategy due to its fast growth. Vachellia macracantha (Humb. & Bonpl. ex Willd.) Seigler & Ebinger presented a unique case, displaying slow germination and a broad range in both root/shoot ratios and growth rates. At the intraspecific level, significant variation in biomass allocation and growth rate was observed, influenced by germination speed and seed weight. We discuss the adaptive significance of seed traits in SDTFs and their role in seedling establishment under varying environmental conditions, providing insights for strategies for conservation and restoration in these ecosystems.

Transcriptome analysis unveiled the genetic basis of rapid seed germination strategies in alpine plant Rheum pumilum

Rheum pumilum stands as both a quintessential alpine plant and a significant traditional Chinese and Tibetan medicinal herb. Unraveling the molecular intricacies of seed germination in Rh. pumilum not only unveils the genetic foundations of plant seed germination strategies in high-altitude environments but also offers insights for cultivating Rh. pumilum medicinal materials. Employing transcriptome sequencing and the Weighted Gene Co-expression Network Analysis, this study delved into the shifts in gene expression levels across various stages of seed germination in Rh. pumilum. The process of seed germination in Rh. pumilum entails a cascade of complex physiological events. Six hormones (ABA, IAA, ETH, GA, BR, CK) emerged as pivotal players in seeds breaking in shells and the facilitation of rapid seed germination in Rh. pumilum. Fourteen transcription factor families (LOB, GRAS, B3, bHLH, bZIP, EIL, MYB, MYB related, NAC, TCP, WRKY, HSF, PLATZ, and SBP) along with four key genes (E2.4.1.13, EIN3, BZR, and BIN2) were identified that may be associated with both biotic and abiotic environmental stress. The ETR, ACACA and ATPeV0C genes were linked with energy accumulation during the initial stages of seed germination, CYP707A may play an important role in breaking seed dormancy, while the BRI1 gene may be correlated with swift seed germination. Additionally, several unidentified genes were recognized to play key roles in seed germination of Rh. pumilum, warranting further investigation. Moreover, Rh. pumilum demonstrates full activation of crucial physiological functions such as energy metabolism, signal transduction, and responses to biological and abiotic stresses during the seed breaking in shells. This study provides molecular evidence elucidating the swift seed germination strategies adopted by alpine plants to thrive in high-altitude environments. Furthermore, it serves as a foundational reference for enhancing seed germination rates and breeding practices to promote the sustainable development of Rh. pumilum medicinal materials.

Germination of the exotic Calotropis procera (Aiton) W.T. (Apocynaceae) in Mexico

Background: Seed germination strategies are important for exotic species to identify the factors that control seed germination and establishment.
 Questions and /or Hypotheses: Temperature and light germination requirements for seeds of Calotropis procera do not change neither in its native regions nor in lands where it is exotic. Calotropis procera show germination traits that may increase their probability of colonization.
 Studied species: Calotropis procera is a perennial plant native to some desertic areas in Asia and Africa and now naturalized in America.
 Study site and dates: Mature fruits were collected in Oaxaca in September 2019 to test germination parameters. The last experiment was conducted in September 2021.
 Methods: We determined the effect of different temperatures, photoblastic response, and loss of viability of seeds kept at laboratory conditions for two years. We performed several sowings under controlled conditions and achieved germinability, t50 and the time to germinate.
 Results: Seeds were non-dormant, neutral photoblastic and did not lose viability after two years of dry storage. Temperature affected germinability and t50. Optimum germination temperature was 30 °C with no germination above 40 °C.
 Conclusions: Germination requirements of seeds of Calotropis procera studied were similar to those reported worldwide. Though seed germination was affected by maximum mean temperatures, seeds germinated fast and at high percentages under a wide range of temperatures, which together with other attributes, may confer C. procera great chances for successful colonization.

The ecological roles of seed mucilage on germination of Lepidium perfoliatum, a desert herb with typical myxospermy in Xinjiang

Myxospermy is considered as an adaptation to unideal habitats, which is characterized as a gelatinous layer of mucilage around the seed upon contact with water. Studies on the ecological roles of seed mucilage should provide valuable information on seed germination strategy. In the present study, the germination properties of Lepidium perfoliatum L., an early spring ephemeral plant with typical myxospermy in desert of northwestern China, were investigated with the intact seeds and demucilaged seeds under different conditions. Results revealed that, firstly, the seed mucilage was essential for intact seeds to germinate quickly and efficiently under abundant or excess water condition, while had no effect on relief of seed germination at low water potential or other stressful conditions; secondly, the presence of mucilage layer stimulated intact seed germination under relatively higher temperature, appropriate light, permeable soil matrix, which helps seed germinate efficiently under favorable conditions; thirdly, the existence of mucilage may limit air diffusion into seed and subsequently reduce germination, which might be a strategy to ensure a proportion of seeds staying in soil seed bank to wait for next favourable conditions. Our results suggest that the seed mucilage of L. perfoliatum applies multiple ecological roles in protection of seed germination to avoid unfavourable conditions, which should be an adaptation strategy for population survival and succession in a harsh desert environment.

Seed germination, growth and chlorophyll a fluorescence in young plants of Allophylus edulis in different periods of flooding

The distribution of woody species in flooded environments depends on the duration of stress as well as seed germination strategies and plant morphophysiological adaptations. Allophylus edulis is a tree that occurs in temporarily or permanently flooded areas in several countries of South America. In this paper, we evaluate seed germination, growth parameters, photosynthetic pigment contents and chlorophyll a fluorescence in young plants to understand the tolerance of the specie to flood events. The evaluations were performed in non-flooded (NFL) and flooded (FL) plants in a temporal scale that included short (up to 30 days) and long (up to 90 days) flood periods. A short flooding (15 days) may favor germination but maintaining stress for 60 days makes the seeds unviable. Although 71.4% of the FL plants survived up to 90 days of flooding, injuries such as chlorosis and foliar abscission appeared. An increase in stem height and diameter was only observed in NFL plants; whereas, FL plants showed a growth inhibition. At 90 days, NFL and FL plants presented total dry mass of 18.35 ± 1.57 g and 1.93 ± 0.62 g, respectively. The photosynthetic performance indexes indicated acclimatization of the plants on the third day of flooding, but the stress induced a progressive decline in the parameters, signaling damages to the photosystem II. Both seeds and young plants of A. edulis tolerate short periods of flooding, but prolonged floods make the seeds unfeasible and damages the photosynthetic apparatus, leading to death of the plants.

Changes in seed germination strategy along the successional gradient from abandoned cropland to climax grassland in a subalpine meadow and some implications for rangeland restoration

Various plant successional gradients on the Qinghai-Tibetan Plateau are created by overgrazing of rangelands and by abandonment of cultivated land. A key point for restoration of these grasslands is the germinability of seeds that are sown in the field. Thus, information on how germination strategies change during succession will be helpful in restoring the grasslands in different successional stages. We sampled subalpine meadows abandoned from agriculture for 1, 5 and 15 years and an undisturbed (climax) meadow. Seed germination of species of communities in different successional stages and the climax were tested in the laboratory under different conditions. Change in germination strategy from the pioneer stage to climax was analyzed at the community level. Our results indicated that 1) at the community level, germination of species in the pioneer stage of succession (SS) is significantly different with that of those in the later SS; 2) species in the pioneer SS germinated better at 10-25℃ than those in the later (5 and 15 years) stages and in the climax; 3) the optimal temperature range for germination for the 1-year-old and climax communities (15-25℃) is wider than that of the 5- and 15-year-old communities (20-25℃); 4) germination of species in the 5- and 15-year-old communities had a significant positive response to alternating temperature and wet-cold storage but the 1-year-old and climax communities did not; 5) the SS has different effects on the diversity index for a single germination trait (FDrao), depending on the kind of trait, however, the diversity for the suite of seed germination traits (FRic) tends to decrease with progression of succession; 6) both species richness and phylogenetic diversity increase with progression of succession. Thus, the seed germination strategy changed with the progression of succession, and it was correlated with changes in vegetation density and height along the successional gradient. This research can give us some guidelines for grassland restoration by adding seeds.

Oxalis seeds from the Cape Flora have a spectrum of germination strategies.

Seed germination strategy has profound ecological and evolutionary consequences, with transitions between germination strategies receiving renewed recent attention. Oxalis from the Cape Flora, South Africa, has seeds with two contrasting germination strategies: orthodox and recalcitrant. The morphological gulf between these strategies (and potential intermediate morphologies) has been poorly quantified, with questions regarding their ecological function and evolution. We reconsidered this binary classification, emphasizing potential intermediate states. Seed physiological traits were used to assign strategies to 64 Oxalis species. We tested for morphological/phenological signal corresponding to defined strategies with cluster, principal component, K-means clustering and discriminant analyses. We showed that an intermediate germination strategy does exist among Cape Oxalis, with two possible morphological groups within each strategy. These could reflect a continuum of germination states, where an ancestral orthodox strategy evolved toward a maximally recalcitrant peak, with a mosaic of intermediate states reflected in extant taxa. Environmental factors may affect germination strategy and distribution throughout the Cape because recalcitrant and intermediate species are confined to the winter rainfall region. They occupy specialized niches and may face adverse impacts under predicted climate change (hotter and drier winters), meriting focused future conservation.

Broad Seed Germination Niche as an Adaptation to Heterogeneous Aquatic Habit—a Case Study of Four Potamogeton species

Aquatic habitats represent an extremely heterogeneous media for the inhabiting its plants, because key environmental factors vary there rapidly at relatively small scales. In this study, we explore the seed germination strategies of four pondweed species (Potamogeton compressus L., P. natans L., P. pectinatus L. and P. vaginatus Turcz.) in relation to the habitats they occupy. We hypothesised that, due to the high heterogeneity of aquatic environments, none of the environmental factors, such as light, temperature fluctuations or oxygen would play the role of a reliable trigger for seed germination of these species. The results of the germination experiments confirm the proposed hypothesis: under almost all conditions – fluctuating and constant temperatures, light and darkness, aerobic, flooded and hypoxia conditions – germination percentages ranged from 88.5 to 100%. An interspecific comparison of germination patterns also evidenced that all the investigated species showed the same response to all the studied environmental factors. We speculate that similar adaptations present in other aquatic macrophytes may point out the broader occurrence of this phenomenon in aquatic plants.

Functional traits associated with plant colonizing and competitive ability influence species abundance during secondary succession: Evidence from subalpine meadows of the Qinghai-Tibetan Plateau.

It is widely recognized that colonists and competitors dominate early and late succession, respectively, with selected species having different colonizing and competitive abilities. However, it remains unknown whether colonizing and competitive ability can determine species abundance directly over succession. The data for five key functional traits were collected (photosynthesis rate, leaf turgor loss point, leaf proline content, seed mass, and seed germination rate), which are direct indicators of plant competitive and colonizing abilities including growth, drought and cold stress resistance, dispersal, and seed dormancy. Here, we tested the effects of colonizing and competitive abilities on species abundance, by employing a linear mixed‐effects model to examine the shifts in the relationship between species abundance and these five colonization and competition‐related traits in species‐rich subalpine secondary successional meadows (at 4, 6, 10, 13 years of age, and undisturbed, respectively) of the Qinghai–Tibetan Plateau. The abundant species at the early‐successional meadows tend to have high photosynthetic rate, high leaf proline content, low seed mass, and seed germination rate for having high colonizing ability, but low competitive ability. By contrast, late‐successional communities tend to be dominated by species with high competitive ability, but low colonizing ability, indicated by large seeds, high seed germination rate, low photosynthetic rate, and leaf proline content. The observed directional shifts in the relationships between traits (photosynthetic rate, leaf proline content, seed mass, and seed germination rate) and abundance with successional age, bring two new understandings of community assembly during succession of subalpine meadows in the Qinghai–Tibetan Plateau. First, it discloses that the differences in species abundance over succession can be directly attributed to differences in colonizing and competitive abilities of different species. Second, it expands the effects of multiple life historical differences including growth, resource competitive ability, cold stress resistance, dispersal, and seed germination strategy, represented by functional traits on community assembly along succession, that is, from the species to the community level.

Climatic control of germination in the genus Silene L

Background: Seed germination strategies depend on a number of factors such as climatic variables, habitat, life cycle, phylogenetic affiliation and morphological seed traits.Aims: We present a novel evaluation of the ecological correlates of germination strategies focussing on plant populations drawn from a single genus and considering a number of relevant explanatory variables.Methods: Temperature and light-controlled germination experiments were carried out on 21 seed accessions belonging to 13 closely related species of the genus Silene L. Accessions were selected to tightly control the phylogenetic effect and give broad ecological and geographic coverage of the genus in Europe, with three North American and Macaronesian outgroups from climatically extreme environments. We used principal component analysis and correlation analyses to identify the correlation structure of germination traits and include multiple explanatory variables.Results: Three germination strategies were shown to be related to climatic control. (1) Seeds from arid regions with hot, dry summers germinated optimally at cool temperatures associated with the rainfall period under field conditions, whereas (2) the benefit of cold stratification was more marked in provenances characterised by cold, dry winters, and (3) seeds from mild climates preferred warm temperatures for germination. Moreover, (4) biennial populations of disturbed habitats showed synchronised and rapid seed germination over a wide thermal window. In agreement with previous findings, (5) habitat-related syndromes were observed only for wetland populations. Correlations with seed mass were significant when related to summer precipitation, but weak or absent in relation to germination traits, indicating that, though influenced by the local climate, seed mass is a poor predictor of germination strategies.Conclusions: These results suggest that whilst habitat and life cycle might shape germination patterns to a certain extent, long-term climatic differences play a substantial role in selecting specific germination traits and strategies.

Seed germination of Caragana species from different regions is strongly driven by environmental cues and not phylogenetic signals

Seed germination behavior is an important factor in the distribution of species. Many studies have shown that germination is controlled by phylogenetic constraints, however, it is not clear whether phylogenetic constraints or environmental cues explain seed germination of a genus from a common ancestor. In this study, seed germination under different temperature- and water-regimes [induced by different osmotic potentials of polyethylene glycol (PEG)] was investigated in the phylogenetically-related Caragana species that thrive in arid, semiarid, semihumid and humid environments. The results showed that the final percentage germination (FPG) decreased from 95% in species from arid habitats to 0% in species from humid habitats, but with no significant phylogenetic signal. Rather, the response of seed germination to temperature and PEG varied greatly with species from arid to humid habitats and was tightly linked to the ecological niche of the species, their seed coat structure and abscisic acid concentration. The findings are not consistent with the hypothesis that within a family or a genus, seed germination strategies can be a stable evolutionary trait, thus constraining interspecific variation, but the results clearly show that seed germination of Caragana species distributed across a range of habitats has adapted to the environment of that habitat.

Phylogeny, Seed Trait, and Ecological Correlates of Seed Germination at the Community Level in a Degraded Sandy Grassland.

Seed germination strongly affects plant population growth and persistence, and it can be dramatically influenced by phylogeny, seed traits, and ecological factors. In this study, we examined the relationships among seed mass, seed shape, and germination percentage (GP), and assessed the extent to which phylogeny, seed traits (seed mass, shape, and color) and ecological factors (ecotype, life form, adult longevity, dispersal type, and onset of flowering) influence GP at the community level. All analyses were conducted on the log-transformed values of seed mass and arcsine square root-transformed values of GP. We found that seed mass and GP were significantly negatively correlated, whereas seed shape and GP were significantly positively correlated. The three major factors contributing to differences in GP were phylogeny, dispersal type, and seed shape (explained 5.8, 4.9, and 3.1% of the interspecific variations independently, respectively), but GP also influenced by seed mass and onset of flowering. Thus, GP was constrained not only by phylogeny but also by seed traits and ecological factors. These results indicated that GP is shaped by short-term selective pressures, and long-term phylogenetic constrains. We suggest that correlates of phylogeny, seed traits, and ecology should be taken into account in comparative studies on seed germination strategies.

Seed germination strategies: an evolutionary trajectory independent of vegetative functional traits.

Seed germination strategies vary dramatically among species but relatively little is known about how germination traits correlate with other elements of plant strategy systems. Understanding drivers of germination strategy is critical to our understanding of the evolutionary biology of plant reproduction.We present a novel assessment of seed germination strategies focussing on Australian alpine species as a case study. We describe the distribution of germination strategies and ask whether these are correlated with, or form an independent axis to, other plant functional traits. Our approach to describing germination strategy mimicked realistic temperatures that seeds experience in situ following dispersal. Strategies were subsequently assigned using an objective clustering approach. We hypothesized that two main strategies would emerge, involving dormant or non-dormant seeds, and that while these strategies would be correlated with seed traits (e.g., mass or endospermy) they would be largely independent of vegetative traits when analysed in a phylogenetically structured manner.Across all species, three germination strategies emerged. The majority of species postponed germination until after a period of cold, winter-like temperatures indicating physiological and/or morphological dormancy mechanisms. Other species exhibited immediate germination at temperatures representative of those at dispersal. Interestingly, seeds of an additional 13 species “staggered” germination over time. Germination strategies were generally conserved within families. Across a broad range of ecological traits only seed mass and endospermy showed any correlation with germination strategy when phylogenetic relatedness was accounted for; vegetative traits showed no significant correlations with germination strategy. The results indicate that germination traits correlate with other aspects of seed ecology but form an independent axis relative to vegetative traits.

Variation in seed germination of 86 subalpine forest species from the eastern Tibetan Plateau: phylogeny and life‐history correlates

AbstractWe have examined the seed germination strategy of 86 subalpine woody species from the eastern part of the Tibetan Plateau and assessed correlations between seed germination and phylogeny, life‐history attributes, habitat, and altitude using stepwise analyses of variance (ANOVAs) and phylogenetically independent contrasts (PICs). A series of ANOVAs revealed that the total amount of variance in the arcsine‐transformed value of germination percentage among species could be accounted for by phylogeny (19.2%) and dispersal mode (14.3%) in seeds incubated in the light and by phylogeny (29.3%) and dispersal mode (11.0%) in those incubated in the dark. In addition, the total amount of variance in T50 (days to half of the final germination) can be accounted for by phylogeny (22.7%) and dispersal mode (17%) in seeds incubated in the light and by phylogeny (32.1%) and dispersal mode (9.9%) in those incubated in the dark. PICs indicated a significant correlation between germination percentage and dispersal mode and a positive correlation between T50 and seed mass, showing that wind‐dispersed seeds had higher germination percentages than both unassisted and vertebrate‐dispersed seeds and that small seeds germinated faster than large ones. We suggest that phylogeny and dispersal mode may constrain variation in seed germination across species and that the speed of germination and seed mass may co‐vary to adapt to a variable environment. Therefore, from an evolutionary perspective, seed germination might be the result of both selective pressures over long‐term ecological time and phylogenetic constraints over the long‐standing evolutionary history of the phylogenetic group.

Divergence in germination traits among arctic and alpine populations of Koenigia islandica: light requirements

Light is known to regulate conservative germination strategies and the formation of seed banks. Although these strategies are crucial to survival in tundra environments—especially for annuals—light requirements for germination in arctic–alpine species are seldom investigated. Furthermore, environmental differences between arctic and alpine regions are expected to lead to evolutionary divergence among conspecific populations in seed germination strategies. In this study, we report important differences in germination light requirements among six arctic and alpine populations of the annual Koenigia islandica. Light had little effect on germination of the seeds from Iqaluit (Nunavut, Canada), Yukon (Canada), and Jasper (Alberta, Canada), whereas the seeds from the most severe climates, Svalbard (Norway) and Colorado (USA), had strong light requirements. Stratification of the seeds had little influence on their germination light requirements, with the exception of the population from Dovre (Norway), in which it induced a strong light requirement. Possible adaptive explanations and some implications of these observed germination patterns are discussed.

Annual plants in arid and semi-arid desert regions

Annual plants are the main vegetation in arid and semi-arid desert regions. Because of their unique traits, they are the optimal experimental subjects for ecological studies. In this article, we summarize annual plants’ seed germination strategies, seedling adaptability mechanism to environments, seed dispersal, and soil seed banks. We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities. Because annual plants have important ecological functions in desert vegetation systems, this study on annual plants will be of great benefit to the conservation and restoration of desert ecosystems, the rational utilization of resources, and the sustainable development of desert regions.

Effect of Temperature, Light, Seed Weight and GA3 on the Germination of Verbascum bithynicum, Verbascum wiedemannianum and Salvia dicroantha

S. dicroantha, (Stapf in Denkseehr) Verbascum bithynicum and V. wiedemannianum are (Bioss.) endemic and medicinal potential plants disturbed in Turkey. V. wiedemannianum is different from the other Verbascum species in red-dark purple flowers and as a threated plant. Seed germination strategies of these species were studied with the aim of producing appropriate germination protocols for use ex situ conservation. The optimum temperature for seed germination of S. dicroantha, V. bithynicum and V. wiedemannianum was 200C and darkness. The seeds of V. bithynicum and V. wiedemannianum incubated in darkness showed higher germination percentages than the seeds incubated with a 16:8 h photoperiod or continuous light, but the effect of application of darkness,photoperiod (16:8 h) or continuous light on the germination percentage of the seeds of S. dicroantha was not significant. In the case of S. dicroantha, seed weight significantly affected germination percentage, but not significant in the case of V. bithynicum and V. wieqemannianum. Exogenous GA3 (20, 100, 200 mg L(-1)) was comletely prevented germination the seeds of these species.

Seed Germination Strategies of Species With Restoration Potential in a Fire-Maintained Pine Savanna

Seed germination phenology studies are important tools for determining whether seeds exhibit dormancy and what environmental conditions trigger germination. Within longleaf pine (Pinus palustris Miller) ecosystems of the southeastern United States Coastal Plain, little is known about dormancy patterns and germination cues of the suite of native species composing the diverse fire-maintained ground cover vegetation. We used two methods to determine if several dominant or functionally important herbaceous species were capable of forming a persistent soil seed bank, including: (1) a germination phenology study and (2) a buried seed bag study. Results indicate that within species studied from three common families (Asteraceae, 2 species; Fabaceae, 8 species; and Poaceae, 3 species), species within the Fabaceae family seem most capable of forming long-term persistent seed banks. Although most of the Poaceae and Asteraceae species examined exhibited little dormancy in the germination phenology study, evidence from the buried seed bag study indicates that several species may form transient or even short-term persistent seed banks under favorable conditions. The absence of evidence of persistent seed banking potential for several dominant species examined in this study suggests that seed reintroduction will likely be a necessary component in restoration efforts in longleaf pine ecosystems.

Seed germination strategies of five perennial weeds.

The germination responses of seeds of Achillea millefolium L., Artemisia vulgaris L., Cirsium arvense (L.) Scop., Taraxacum officinale Weber, sensu lato, and Tussilago farfara L. to light, nitrate, alternating temperatures, chilling, light quality, and water availability were studied in laboratory tests, using fresh seed and seed stored for 6 months at 27°C and buried in the soil. A factorial experiment with light, nitrate, alternating temperatures, and seed age as factors found that all four affected germination except in T. farfara. All three external factors were stimulatory, especially in combinations. Fresh seed of A. vulgaris and C. arvense showed a light x alternating temperature synergism, responded to chilling, and after-ripened in cold dry storage. That of T. farfara had no dormancy and rapid germination, and germinated well on substrates with a water content too low for the other species. Seed of A. millefolium and A. vulgaris had good survival in both experimental storage conditions, while that of C. arvense and T. officinale did not, and that of T. farfara did not survive. Longevity in both conditions was associated with depth of initial dormancy. The two conditions caused different changes in dormancy in both A. vulgaris and A. millefolium. The germination behaviour, and the size, morphology and dispersal of the seeds of the species are discussed as strategies adapted to intermittently available situations for seedling establishment.