Effect of light, gibberellic acid and nitrogen source on germination of eight taxa from dissapearing European temperate forest, Potentillo albae-Quercetum

Electrophysiological and Behavioral Responses of Batocera horsfieldi Hope to Volatiles from Pistacia chinensis Bunge

Following infestation by phytophagous insects, changes in the composition and relative proportion of volatile components emitted by plants may be observed. Some phytophagous insects can accurately identify these compounds to locate suitable host plants. We investigated whether herbivore-induced plant volatiles (HIPVs) generated by herbivory on Pistacia chinensis Bunge (Sapindales: Aceraceae) might be semiochemicals for the host location of Batocera horsfieldi Hope (Coleoptera: Cerambycidae). We performed two-choice bioassays (indoor darkroom, inside cages) on plants damaged by adult feeding and intact control plants. Volatiles from these plants were then collected and identified, and the response of adult antennae to these compounds was tested via electroantennography (EAG). The behavioral responses of B. horsfieldi to these compounds were finally assessed using a Y-tube olfactometer. Host plant choice tests show that B. horsfieldi prefers feeding-damaged P. chinensis over healthy trees. In total, 15 compounds were collected from healthy and feeding-damaged P. chinensis, 10 of which were shared in both healthy and feeding-damaged P. chinensis, among which there were significant differences in the quantities of five terpenes, including α-pinene, β-pinene, α-phellandrene, D-limonene, and β-ocimene. In EAG assays, the antennae of B. horsfieldi adults responded strongly to (Z)-3-hexen-1-ol, β-ocimene, 3-carene, γ-terpinene, D-limonene, myrcene, and α-phellandrene. The antennae of B. horsfieldi adults responded in a dose-response manner to these compounds. Y-tube behavioral experiments showed that four compounds attracted mated females ((Z)-3-hexen-1-ol, β-ocimene, 3-carene, and α-phellandrene), two compounds ((Z)-3-hexen-1-ol and α-phellandrene) attracted males, and adults of both sexes avoided D-limonene. Feeding bioassays showed that (Z)-3-hexen-1-ol and β-ocimene could promote the feeding of B. horsfieldi and that D-limonene inhibited this response. These results could provide a theoretical basis for developing attractants or repellents for B. horsfieldi.

Establishment and optimization of a new model organism to study early land plant evolution: Germination, cultivation and oospore variation of Chara braunii Gmelin, 1826

For studying land plant evolution, the establishment and optimization of model organisms representing streptophytic algae, sister to land plants, is essential. Long-term cultivation experiments with Chara braunii S276 were performed over 8 years, since 4 years (Nov. 2018) under constant conditions. Additionally, short-term experiments for optimization of culture conditions were performed with three strains of C. braunii (S276, NIES-1604 and Lausiger Teiche, LaT-2708). Germination success after application of sterilization agents, addition of gibberellic acid and under different incubation conditions with respect to pre-treatment, irradiance regime and substrate was investigated in order to develop protocols for generative cultivation of at least unialgal cultures. The resulting cultivation protocols for C. braunii S276, allowing maintenance of vegetative as well as generative cultures are presented in detail, including protocols for germination induction and growth of sterilized and unsterilized oospores.

Seed ecology of European mesic meadows

BACKGROUND AND AIMS

European mesic meadows are semi-natural open habitats of high biodiversity and an essential part of European landscapes. These species-rich communities can be a source of seed mixes for ecological restoration, urban greening and rewilding. However, limited knowledge of species germination traits is a bottleneck to the development of a competitive native seed industry. Here, we synthesize the seed ecology of mesic meadows.

METHODS

We combined our own experimental data with data obtained from databases to create a combined dataset containing 2005 germination records of 90 plant species from 31 European countries. We performed a Bayesian meta-analysis of this dataset to test the seed germination response to environmental cues including scarification, stratification, temperature, alternating temperature and light. We also used multivariate ordination to check the relationship between seed traits (germination and morphology) and species ecological preferences, and to compare the seed ecology of mesic meadows with that of other herbaceous plant communities from the same geographic area.

KEY RESULTS

The seed ecology of mesic meadows is characterized by (1) high seed germinability when compared with other herbaceous plant communities; (2) low correspondence between seed traits and species ecological preferences; and (3) a deep phylogenetic separation between the two major families, Poaceae and Fabaceae. Poaceae produce many light seeds that respond to gap-detecting germination cues (alternating temperatures and light); Fabaceae produce fewer heavy seeds, which need scarification to break their physical dormancy.

CONCLUSIONS

High germinability of meadow seeds will reduce their capacity to form persistent seed banks, resulting in dispersal limitations to passive regeneration. For centuries, human activities have shaped the regeneration of meadows, leading to a loss of seed dormancy and decoupling seeds from seasonal cycles, as has been found in many domesticated species. The same anthropic processes that have shaped semi-natural mesic meadows have left them dependent on continued human intervention for their regeneration, highlighting the importance of active restoration via seed supply.

Hybrid Treatment via MHz Acoustic Waves and Plasma to Enhance Seed Germination in Mung Bean

We investigate a hybrid treatment-consisting of an atmospheric pressure plasma pretreatment, followed by an MHz surface acoustic waves (SAWs) treatment with either de-ionized (DI) water or plasma activated water (PAW)-on mung beans to accelerate the germination process, as mung bean sprout is one of the important food staples. For the early growth rate (after 320 min), we observe that the hybrid treatment with PAW can lead to approximately 217% higher moisture content for the treated beans when compared with that without hybrid treatment. Additionally, the hybrid-treated beans germinate in around 120 min, while the untreated beans germinate only in around 420 min, that is, 3.5-fold faster for treated beans. This can be attributed to the dominant effect of SAW that accelerates stage 1 water absorption process and the effect of direct plasma and PAW that promote stage 2 metabolism process, leading to the enhancement in stage 3 germination process in early growth rate. For the post growth rate (after 24 h), we observe that the hybrid treatment with DI water can lead to an approximately 44.20% in higher moisture and 71.17% in radicle length when compared with untreated beans. Interestingly, the hybrid treatment with PAW, on the other hand, is observed to have an adverse effect on germination after 24 h, that is, approximately 14.51% lower in moisture content and 43.49% lower in radicle length for the hybrid-treated beans with PAW when compared with that with DI water.

Nitrogen signals and their ecological significance for seed germination of ten psammophilous plant species from European dry acidic grasslands

The presented study evaluated effects of potassium nitrate (KNO₃), ammonium nitrate (NH₄ NO₃) and ammonium chloride (NH₄Cl) on the germination-related characteristics of 10 species from European dry acidic grasslands. Germination was studied under controlled laboratory conditions. The seeds were subjected to KNO₃, NH₄ NO₃ and NH₄Cl in four doses (1, 10, 50 and 100 mM) and to distilled water. Final germination percentage, index of germination velocity and index of germination synchrony were determined. Content of nitrogen in the soil probed from the site of seeds collection was also analyzed. Significant effects of type of the nitrogen compounds and their concentrations were observed. High concentrations of nitrogen-containing salts inhibited completion of germination in almost all species. Helichrysum arenarium and Hypericum perforatum showed preference for NH₄⁺ over NO₃^‒, whereas Arnoseris minima, Alyssum montanum, Jasione montana and Spergula morisonii showed preference for NO₃^‒ over NH₄⁺. Centaurea scabiosa, C. stoebe and Hypochaeris radicata had no preference and wide tolerance to the type of nitrogen-containing compound. Echium vulgare showed differential response hard for interpretation. A. montanum and J. montana showed stenotopic behavior in terms of nitrogen-related conditions. It is proposed that nitrogen-rich soil gaps favor establishment of more nitro-tolerant plant species (e.g. C. scabiosa, C. stoebe and H. radicata) as compared to nitrogen-poor ones.

Direct effects of nitrogen addition on seed germination of eight semi-arid grassland species

Seed germination plays an important role in mediating plant species composition of grassland communities under nitrogen (N) enrichment. Shifts of plant community structure with N-enhanced deposition in terrestrial ecosystems have occurred globally. Despite numerous studies about the effects of enhanced N deposition on mature plant communities, few studies have focused on seed germination. Using a laboratory experiment, we report the effects of five N concentrations, including 0, 5, 10, 20, and 40 mM N (NH4NO3) on seed germination of eight semi-arid grassland species. Results showed that low N concentrations (5- and 20-mM N) promoted mean final germination proportion of all eight species by 4.4% and 6.4%, but high concentrations (40 mM N) had no effect. The mean germination rate was decreased 2.1% and 5.1% by higher N concentration (20- and 40-mM N) levels, but germination start time showed the opposite trend, delayed by 0.7, 0.9, and 1.8 d for the 10, 20, and 40 mM N treatments. Final germination proportion, mean germination rate, and germination start time were significantly different among species in response to N concentration treatments. The final germination proportion of Allium tenuissimum and Chenopodium glaucum were suppressed by increased N concentration, whereas it increased for Potentilla bifurca, Plantago asiatica, and Setaria viridis. Our findings provide novel insights into N deposition-induced species loss based on seed germination factors in semi-arid grassland communities.

Nitrogen addition decreases seed germination in a temperate steppe

Seed germination and seedling establishment play an important role in driving the responses of plant community structure and function to global change. Nitrogen (N) deposition is one of the driving factors of global change, which often leads to a loss in species richness in grassland ecosystems. However, how seed germination responds to N addition remains unclear. A pot incubation test was conducted in a semi-arid grassland in the Mongolian Plateau, Northern China, to investigate the effect of N addition (0, 5, 10, 20, 40, and 80 g N/m2) on seed germination from May to October 2016. Twenty species germinated under all treatments; however, the responses of the 20 species to N addition were different. The densities of Stipa krylovii, Leymus chinensis, and Artemisia frigida, which are the dominant species in this temperate steppe, decreased significantly as the amount of N addition. Moreover, N addition significantly suppressed seedling densities of the community, perennial forbs, perennial grasses, and annuals and biennials. Furthermore, species richness of the community, perennial forbs, and annuals and biennials decreased sharply with increasing N addition level, but perennial grass species richness did not change. The Shannon-Wiener diversity index also decreased as the amount of N addition increased. Our results suggest that N enrichment plays an important role in the seed germination stage and decreases supplements of seedlings to adult plants. These findings may help explain the causes of species loss by atmospheric N deposition in grassland ecosystems.