Final Germination Rate Research Articles

Biofertilizer based on <i>Agrobacterium </i>as a key to food security

Background: The concept of food security is contingent upon the fulfillment of two fundamental requirements: physiological and socioeconomic. The former comprises providing sustenance that is both safeguarded and enhanced in line with people’s nutritional needs and priorities, whereas the latter includes the mechanisms by which these needs are supplied. The objective is to ensure a state of robust and healthy well-being. As a sustainable solution, biofertilizers play a pivotal role in addressing the challenges of food security. Biofertilizers represent a cost-effective and environmentally friendly solution, with the potential to enhance soil productivity through nitrogen fixation. They also enhance crop yield by increasing the concentration of nutrients. Access to functional foods derived from biofertilizer-enhanced yields may contribute to improved dietary diversification and overall well-being. Objective: The objective is to isolate and screen the most active nitrogen-fixing bacterium as a basis to a new biofertilizer. Methods: The isolation of nitrogen-fixing bacteria was conducted using the soil sowing technique. The selection of nitrogen-fixing bacteria was based on their morphophysiological characteristics. Bacterial growth was evaluated by viable cell count. Cultivation of the selected bacterium occurred in both flasks (on a shaker) and a bioreactor to compare growth conditions. The stimulatory effect of the selected bacterium on seed germination was assessed based on the final germination rate. The selected bacterium identified through molecular taxonomy. Results: A total of 100 pure cultures were isolated, from which nitrogen-fixing bacteria were selected. The cultivation conditions for these bacteria were optimized regarding pH, temperature and process duration in a flask on a shaker. Strain NB4 exhibited the most favorable development under optimal settings. Additionally, cultivation parameters for this strain were optimized in a laboratory bioreactor. Notably, a bacterial liquid culture water solution comprising 1.5% strain NB4 facilitated complete germination of wheat (Triticum aestivum L.), seeds and produced high-quality sprouts. The 16S rRNA gene sequence of strain NB4 was submitted to the GenBank database under accession number MT670424.1, identifying it as Agrobacterium Pusense RP 1. Conclusion: This research aimed to develop an effective biofertilizer to tackle the pressing issue of food security. The project’s cornerstone was Agrobacterium pusense RP 1, nitrogen-fixing strain isolated and identified through rigorous research. Keywords: Isolation and identification of nitrogen-fixing bacteria, cultivation in bioreactor, germination of wheat seeds, Agrobacterium pusense.

Variations in Seed Dormancy Occurrence and Their Classifications in Thirteen Actinidia Species

As differences in seed dormancy between Actinidia species have not been reported previously, in this study we characterized the variation in the dormancy of seeds in 13 kiwifruit species that originated from different regions of China and Taiwan, and for which mature plants are now growing in New Zealand orchards. Dormancy-breaking treatments, including cold-moist stratification, seed coat scarification and soaking in water and gibberellic acid (GA3), were tested for their efficacy in alleviating dormancy and improving final germination and germination rates. In addition, we assessed seed viability using RNA integrity analysis to distinguish dead seeds from dormant seeds. This study identified that dormancy type in Actinidia seeds is species-specific and can be morphological, morphophysiological or a combination of physiological and physical, and that seed RNA integrity is a useful metric to incorporate into seed dormancy studies. Our results also suggest that species originating from colder climates that experience large differences between winter minimum and summer maximum temperatures exhibit physiological dormancy and require cold-moist stratification, contrasting with species originating in milder climates. Interestingly, although not all seeds from all the species were dormant, the proportion of dormant seeds in each species did not correlate to the climatic data of the region from which they originated. These findings provide new insights into mechanisms of seed dormancy in kiwifruit.

Exploring germination requirements of Iva xanthiifolia: Implications for potential spread in Europe

Iva xanthiifolia, an invasive annual weed species native to North American prairies, is an agricultural problem in different parts of the world and represents a health hazard as an allergen to humans. This study addresses the limited literature on its germination requirements, focusing on base temperature, base water potential, and salinity tolerance. Seeds from a Serbian population near Belgrade were tested to various conditions. The experiments were conducted using temperatures ranging from 1 °C to 30 °C and water potentials ranging from 0 to –2 MPa, while salinity tolerance was tested at three temperatures (1, 3, and 6 °C) and five salinity levels (0 to 16 dS/m). Results indicate higher germination rates at lower temperatures (1 °C) compared to higher temperatures (30 °C), with a base temperature of 0.7 ± 0.37 °C. Germination decreased with increased water potential, showing a base water potential of -1.58 ± 0.07 MPa. Salinity tolerance was observed, with germination even at 16 dS/m (the final germination rate was 54.5 % ±2.88). Additionally, germination was observed declining with increasing temperature in a saline environment. As germination is one of the major determinants of a species’ success, the possible spreading of this species under different climate change scenarios was simulated. Results of future distribution modelling suggested sensitivity to precipitation changes and potential northward expansion of this species. This research enhances our understanding of Iva xanthiifolia traits, useful for supporting management strategies for its control and mitigation of its impact, even under future climate change and land-use scenarios.

Germination Characteristics and Seedling Growth of <italic>Pseudolysimachion nakaianum</italic> (Ohwi) T. Yamaz. Seeds According to Light Quality Type

Background and objective: This study was conducted to understand the effect of different quality of light-emitting diodes (LED) on the germination characteristics and growth of <i>Pseudolysimachion nakaianum</i>.Methods: The LED light irradiation was divided into white, red, blue, and red:blue (1:1). To investigate the germination characteristics, 30 seeds were placed in a Petri dish in three replicates for 8 days. Average germination rate, germination speed, germination uniformity, and average germination time were measured. To investigate the growth of seedlings, plant height, plant width, leaf length, leaf width, leaf number, fresh weight, dry weight and T/R ratio were examined 6 weeks after sowing, and chlorophyll fluorescence (maximum quantum yield, electron transport rate) was measured.Results: The final germination rate and germination speed were highest at red:blue (1:1) LED irradiation. Regarding growth and chlorophyll fluorescence measurements, red:blue LED showed the best growth results, with no significant difference in Fv/Fm between different types of light quality, and the electron transport rate was the highest under red:blue LED irradiation. Also, total fresh/dry weight and T/R ratio were highest for red:blue LED, it is presumed to promote the biomass of entire plant.Conclusion: The results proved that <i>Pseudolysimachion nakaianum</i> showed red LED conditions promoted germination, but cultivation under red:blue LED conditions is judged to be suitable for seedling growth and photosynthesis.

Adaptive responses and transgenerational plasticity of a submerged plant to benthivorous fish disturbance.

Submerged macrophytes play a key role in the restoration of shallow eutrophic lakes. However, in some subtropical lakes, benthivorous fishes dominate the fish assemblages and influence the growth of submerged plants. A comprehensive understanding of the direct and indirect effects of benthivorous fishes on submerged plants is important. We conducted mesocosm experiments to examine the effects of three densities of benthivorous fish, Misgurnus anguillicaudatus, on the water properties, the growth, asexual reproduction, and the germination of turions of Potamogeton crispus L. Our results showed that fish disturbance increased TN, TP, PO4-P, NH4-N, and NO3-N of the water, raising the extinction coefficient K, Chl a, and the periphyton biomass. Benthivorous fish disturbance reduced the total biomass, root length, relative growth rate (RGR), and branching number while increasing the plant height of P. crispus. The P stoichiometric homeostasis coefficient (H P) (except turions) and H N was lower in plant tissues due to fish disturbance. Benthivorous fish disturbances promoted turions formation (e.g., increased turions total numbers and biomass) of P. crispus. Moreover, P. crispus exhibited transgenerational plasticity for benthivorous fish affecting turion emergence. The maximum final germination rate occurred only when fish density in the mother plant grow experiment matched that in the turion germination experiment. Turions generated by P. crispus disturbed by low-density fish exhibited increased germination rates. Our findings suggest that controlling benthivorous fish reduces its indirect and direct effects on submerged vegetation, facilitating the successful restoration of these plants.

Parthenium hysterophorus Weed Fecundity and Seed Survival at Different Soil pH and Burial Conditions

Parthenium hysterophorus L. is regarded as one of the most invasive weed species. This study evaluated the effect of soil pH on P. hyterophorus weed growth and fecundity, as well as the effect of burial depths on P. hyterophorus seed survival and emergence. The first study evaluated five soil pH levels (acidic, sub-acidic, neutral, sub-basic, and basic) in a randomised complete block design. Seed germinability and subsequent seedling growth (height, leaf area, biomass, and seed number/plant) were evaluated. This study showed that P. hysterophorus seeds have a similar germination capacity under varying soil pH conditions. However, acidic soil indicated accelerated growth (25% higher biomass with 15.2% more leaf area) and fecundity (13.4% faster to enter the flowering stage at 74 days after sowing). In the second study, two factors were tested; burial depths (0.5, 5, 10, and 20 cm) being nested into seven burial durations (0, 2, 4, 6, 8, 10, and 12 months). Seed viability (final germination percentage and germination rate index), electrical conductance, and emergence percentage were assessed with the burial conditions. The results showed that only seed buried at 0.5 cm depth indicated emergence (81.3% of cumulative emergence). Forty per cent of the seeds remained viable after exhumation at 0.5–5 cm depth, while only 19–27% survived as the burial depth increased beyond 10 cm depth within 12 months. The seed remained viable for more than 12 months as a seed bank, despite faster deterioration at increasing soil depth.

Effects of cadmium stress on fruits germination and growth of two herbage species.

Cadmium (Cd) pollution is a global environmental problem. It is of great significance to find a kind of pasture that can grow normally in a cadmium environment, especially in the Tibetan Plateau. We studied the fruit germination and fruit growth of Elymus sinsubmuticus S.L. Chen and Elymus tangutorum (Nevski), native plants of the Tibetan Plateau, in different cadmium environments. The results showed that with increased cadmium stress, the fruit germination rate, final germination rate, fruit-vigor, average germination time, and germination-speed index for the two grass species gradually decreased, and the 50% germination time for the seed gradually increased. Root length, biomass, and the number of leaves decreased in both species. We quantified the fruit germination and growth of plants in the cadmium environment and found that E. sinosubmuticus S.L. Chen had better fruit germination and fruit growth, and it had the development potential of cadmium pollution control.

Phytotoxic Impact of Mesquite (Prosopis juliflora) Pericarps on Seed Germination and Seedling Growth of Lettuce (Lactuca sativa)

Phytotoxic effects of mesquite (Prosopis juliflora) pericarps onseed germination and seedling growth of lettuce (Lactuca sativa) wereinvestigated. Aqueous extracts of 10, 20, 30, 40, 50 and 60 g of drymesquite pericarps in a litre of distilled water were used. Final seedgermination percentage and germination rate, evaluated with correctedgermination rate index, and days to 50% of the final seed germination,were significantly reduced. Likewise were the radicle and the hypocotyllengths, five days after germination. The magnitude of the reductionincreased with the increase of extract concentration. Mannitol solutionswith the same osmotic potential and pH as the aqueous extracts resulted insignificantly higher values of these traits than their correspondingextracts. This indicates that mesquite pericarp contains allelochemicalswhich could detrimentally affect seed germination and seedling growth oflettuce.

Phytotoxic Impact of Mesquite (Prosopis juliflora) Pericarps on Seed Germination and Seedling Growth of Lettuce (Lactuca sativa)

Phytotoxic effects of mesquite (Prosopis juliflora) pericarps onseed germination and seedling growth of lettuce (Lactuca sativa) wereinvestigated. Aqueous extracts of 10, 20, 30, 40, 50 and 60 g of drymesquite pericarps in a litre of distilled water were used. Final seedgermination percentage and germination rate, evaluated with correctedgermination rate index, and days to 50% of the final seed germination,were significantly reduced. Likewise were the radicle and the hypocotyllengths, five days after germination. The magnitude of the reductionincreased with the increase of extract concentration. Mannitol solutionswith the same osmotic potential and pH as the aqueous extracts resulted insignificantly higher values of these traits than their correspondingextracts. This indicates that mesquite pericarp contains allelochemicalswhich could detrimentally affect seed germination and seedling growth oflettuce.

Establishment of Integrated Propagation System on Grafting Plantlets of Passion Fruit (Passiflora edulis)

As a result of virus disease, producers have to renew passion fruit plantlets every year to ensure yield and fruit quality in Taiwan. Currently, the entire procedure—from the preparation of rootstock seeds to having plantlets ready for planting—may take ∼3 months. The shortage of grafted plantlets in internal and foreign markets is a continuous challenge for the industry. The objective of this study is to improve the production mode to establish a rapid production system of grafted plantlets. The results show that the germination rate and time of rootstock seeds improved remarkably at 30 °C. The final germination rate was 100% within 10 days on average. Application of a complex chemical fertilizer Hyponex No. 4 solution, diluted 1000-fold, by soil drench weekly resulted in seedlings ready for grafting 28 days after treatment. Stem diameter reached 2.5 mm and plant height was ∼10 cm. After grafting, keeping the plantlets at 25 °C with a relative humidity of more than 85% ensured all incisions were healed within 7 days. After moving the plantlets to a semishaded greenhouse for hardening, and maintaining the same temperature and relative humidity for another 7 days, the propagation process was complete. Compared with double-node and shoot-tip scions, the growth and plantlet height of the single-node scion were not the best. However, considering the convenience of scion acquisition and the high rate of propagation, the use of a single-node scion is recommended. It takes only 56 days to propagate grafted plantlets, which is 1 month less using current processes.

Physiological Dormancy and Germination Characteristics of Maianthemum dilatatum (A. W. Wood) A. Nelson and J. F. Macbr. (Asparagaceae)

This study was conducted to elucidate the germination characteristics and dormancy types in Maianthemum dilatatum (A. W. Wood) A. Nelson and J. F. Macbr. M. dilatatum seeds were collected from the Nari Basin on Ulleungdo Island, South Korea and used in a water imbibition test; the seed weight increased by approximately 20% within 48 h. The embryo-to-seed ratio at the time of seed dispersal was 0.57 ± 0.03. When the seeds were incubated under light and dark conditions, they germinated under dark conditions, and the germination rate was higher at 25 °C than at 20 °C. However, the final germination rates under dark conditions were 27.4 ± 3.6 and 47.1 ± 7.6%, respectively. Under 4, 8, 12, and 16 weeks of cold stratification treatment, the highest germination rate of 83.6 ± 3.6% was observed at 25 °C at 12 weeks of cold stratification treatment, the germination start date was decreased by more than 10 d, and the mean germination time (MGT) was shortened from 50 d to 39 d. However, the germination rate, germination start date, and MGT did not differ significantly among the gibberellic acid hormone treatments. Therefore, it was evident that M. dilatatum demonstrated physiological dormancy (PD) that can broken by cold stratification treatment and dark conditions.

Effects of salinity on germination dynamics and seedling development in two amaranth genotypes.

Amaranth (Amaranthus caudatus L.), commonly known as "kiwicha", is a pseudo-cereal considered as the crop of future regarding its excellent nutritional value. It has also beensuggested as a robust alternative to traditional cereal crops in arid and semi-arid regions where abiotic stresses such as drought and salinity have increased due to climate change. In order to study the seedling behavior and germination dynamics of this species against salinity stress, two amaranth genotypes (Red and Green) were randomly chosen among others and our investigation focused on both morphological and physiological traits. Salt stress was applied for 10days. Our results show that Red genotype was more tolerant to salinity compared to Green since that the first gave a higher final germination rate and produced higher biomass. Moreover, the germination parameters are less affected in Red compared to those in Green genotype. The radicules of the first genotype accumulated more Na+ compared to those of the second one. Moreover, at low level of salinity (50mM NaCl), Red genotype showed significant increase in the volatile polyphenol compound content, as well as in the total antioxidant activity, compared to the control (0mM NaCl). Even if the inhibitory action of the methanoic extracts of both Red and Green genotypes was affected by the salinity, they showed an important activity against P. aeruginosa pathogen.

Biological Control and Plant Growth Promotion by Volatile Organic Compounds of Trichoderma koningiopsis T-51.

Trichoderma spp. are widely used in plant disease control and growth promotion due to their high efficacy and multiple biocontrol mechanisms. Trichoderma koningiopsis T-51 is an effective biocontrol agent against gray mold disease by direct contact. However, the indirect physical contact biocontrol potential of Trichoderma spp. is not clear. In this study, the volatile organic compounds (VOCs) produced by T-51 showed high inhibitory activity against plant pathogenic fungi Botrytis cinerea and Fusarium oxysporum. The percentage of B. cinerea and F. oxysporum mycelial growth inhibition by T-51 VOCs was 73.78% and 43.68%, respectively. In both B. cinerea and F. oxysporum, conidial germination was delayed, and germ tube elongation was suppressed when exposed to T-51 VOCs, and the final conidial germination rate of B. cinerea decreased significantly after T-51 treatment. The VOCs from T-51 reduced the Botrytis fruit rot of tomato compared with that noted when using the control. Moreover, the T-51 VOCs significantly increased the size and weight of Arabidopsis thaliana seedlings. Twenty-four possible compounds, which were identified as alkenes, alkanes, and esters, were detected in VOCs of T-51. These results indicate that T. koningiopsis T-51 can exert biological control by integrating actions to suppress plant disease and promote plant growth.

Effects of Temperature, Light and Salinity on Germination of Salsola crassa (Amaranthaceae) Seeds from Different Years

Salsola crassa is a halophytic plant species from the Amaranthaceae family. In this study we aimed to find out the effect of temperature, light, salinity, and age of seeds on germination ability of S. crassa. Seeds of the species were collected in 2013 and 2014, and seed wings which are known as perianth segments, were removed before the experiments. Both seeds from different years were germinated under the same conditions. Two temperature regimes at 5°C/16°C and 8°C/20°C were used under dark and daily photoperiodism at 12 h intervals for determination of the effects of temperature. Seeds were germinated under different NaCl concentrations. Seeds that did not germinate under saline conditions were taken into recovery and the viability of the seeds that did not germinate after recovery were tested with the Triphenyl Tetrazolium Chloride (TTC) test. As a result, photoperiodism positively influenced the germination rate (p<0.05) of seeds from both years. Even though an increase in salinity decreased the germination rate it can be said that S. crassa is an euhalophyte whose seeds can even germinate at 1800 mM NaCl. Although the age of seeds is an important parameter for seed germinability, there was not any statistically significant difference between the seed viability and final germination rates for the S. crassa seeds from 2013 and 2014.

Influence of plasma-activated water (PAW) on the germination of radish, fenugreek, and pea seeds

The present work is focused on investigating the effect of plasma-activated water (PAW) on the seed germination and seedling growth of radish, fenugreek, and pea seeds. A home-made gliding arc discharge (GAD) reactor generated in air under atmospheric pressure and operating at 50 Hz line frequency is used for water activation. PAW was prepared by exposing deionized water to GAD for 5, 10, 15, and 20 min. As a result of plasma treatment, deionized water showed substantial changes in physical characteristics such as pH and electrical conductivity along with chemical parameters such as nitrites, nitrates, and ammonia. The effect on germination was evaluated based on the fraction of germinated seeds and their length at 7 and 12 days after treatment. Seeds irrigated with PAW resulted in a higher imbibition rate than those irrigated by deionized water. When the seeds were irrigated with PAW, the germination parameters such as final germination rate, mean germination rate, coefficient of velocity of germination, germination index, and growth parameters such as shoot/seedling length and vigor index increased. In conclusion, PAW may be utilized to increase the germination rate of seeds.

The Efficiency of Different Priming Agents for Improving Germination and Early Seedling Growth of Local Tunisian Barley under Salinity Stress.

The current work aimed to investigate the effect of seed priming with different agents (CaCl2, KCl, and KNO3) on germination and seedling establishment in seeds of the barley species of both Hordeum vulgare (L. Manel) and Hordeum maritimum germinated with three salt concentrations (0, 100, and 200 mM NaCl). The results showed that under unprimed conditions, salt stress significantly reduced the final germination rate, the mean daily germination, and the seedling length and dry weight. It led to a decrease in the essential nutrient content (iron, calcium, magnesium, and potassium) against an increase in sodium level in both of the barley species. Moreover, this environmental constraint provoked a membrane injury caused by a considerable increase in electrolyte leakage and the malondialdehyde content (MDA). Data analysis proved that seed priming with CaCl2, KCl, and KNO3 was an effective method for alleviating barley seed germination caused by salt stress to varying degrees. Different priming treatments clearly stimulated germination parameters and the essential nutrient concentration, in addition to increasing the seedling growth rate. The application of seed priming reduced the accumulation of sodium ions and mitigated the oxidative stress of seeds caused by salt. This mitigation was traduced by the maintenance of low levels of MDA and electrolyte leakage. We conclude that the priming agents can be classed into three ranges based on their efficacy on the different parameters analyzed; CaCl2 was placed in the first range, followed closely by KNO3, while the least effective was KCl, which placed in the third range.

Seed Germination Responses to Different Incubation Temperatures and Light Treatments in Four <i>Allium</i> species Native to Korea

Allium L. is a perennial plant in the Amaryllidaceae family and includes 1,000 species. There are 24 indigenous Allium species in Korea, and they have a high value as genetic resources. However, there is a lack of research on indigenous Allium species and little research on recently classified or unknown Allium species, such as A. pseudojaponicum, A. dumebuchum, and A. ulleungense. Therefore, this study determined the effects of environmental control (temperature and light) on germination responses of four indigenous Allium seeds (A. longistylum, A. taquetii, A. pseudojaponicum, and A. thunbergii). Germination responses were evaluated by germination percentage (GP), days to 50% of germination of final germination rates (T50), mean germination time (MGT), germination uniformity (GU), and germination speed (GS). GP of A. longistylum and A. pseudojaponicum was more than 50% at 5°C, but A. taquetii and A. thunbergii did not germinate at 5°C. A. pseudojaponicum inhabits beaches in the southern region, and but A. longistylum inhabits near rivers and streams. However, A. taquetii and A. thunbergii mainly inhabit mountainous areas. Therefore, this difference is estimated to be in accordance with the environmental conditions of their habitat. At 5°C, the GP of A. longistylum was improved in dark conditions (90.0%) than in light conditions (68.3%); T50 and MGT were also shortened. The GP of A. taquetti increased at 15°C in the dark than light conditions, and T50 and MGT were shortened at 15°C and 20°C. Also, the GP and GU increased. At 5°C, the GP of A. pseudojaponicum was higher in the dark (83.3%) than in light conditions (70.0%); T50 and MGT were shortened at 15°C, and GS increased in the dark. At 15°C and 20°C of A. thunbergii, T50 and MGT were shortened, and GP increased in the dark. Therefore, in the relatively low-temperature group, dark conditions improved some germination responses than the light condition. Most of the four Allium seeds used in the experiment showed more than 90% GP at 15°C - 25°C, but other germination responses showed differences according to temperature and light. The T50, MGT, and GS of A. longistylum and A. thunbergii were the most improved at 20°C and 25°C, while A. taquetii and A. pseudojaponicum had the shortest T50 and MGT at 25°C, and the GS was the fastest. As a result, regardless of light, the proper temperature was 20°C – 25°C for A. longistylum, 25°C for A. taquetii, 25°C for A. pseudojaponicum, and 25°C in darkness and 20°C – 25°C in light for A. thunbergii.

Selenium and zinc oxide nanoparticles modulate the molecular and morpho-physiological processes during seed germination of Brassica napus under salt stress

The advent of the nanotechnology era offers a unique opportunity for sustainable agriculture, and the contribution of nanoparticles (NPs) to ameliorate abiotic stresses became the new area of interest for researchers due to their special physiochemical characteristics in the biological system. Salinity is a key devastating abiotic factor that hinders the development and yield of rapeseed. On the flip side, the impact of nanoparticles on plant hormones upon salt stress during seed imbibition and germination has been poorly understood. Hence, we aimed to study the influence of nanopriming on plant hormones and germination processes using selenium and zinc oxide nanoparticles (SeNPs and ZnONPs) during seed imbibition and the early seedling stage upon salinity stress. Nanopriming showed a positive effect on final germination percentage, germination rate, seed microstructure, and antioxidant enzyme activity of two rapeseed cultivars under salt stress. Moreover, nano-treatment decreased the expression of abscisic acid related genes BnCYP707A1, 3, and 4 during the priming time and after sowing, where the levels of BnCYP707A1, and 3 genes showed a slightly significant difference between the nanopriming and hydropriming, which gave an evidence that the nanopriming influenced the ABA levels then elevated the seed germination with SeNPs and ZnONPs. Likewise, nanoparticles significantly elevated the expression levels of BnGA20ox, BnGA3ox and BnCPS genes during the germination stage, especially at 24 h after being sown in salt stress. That confirms the positive role of SeNPs and ZnONPs in regulating gibberellic acid level, which increases the germination in primed seeds as compared to unprimed seeds and hydroprimed seeds. Additionally, our results demonstrated that nanopriming regulated the expression level of BnCAM and BnPER during priming time and after sowing, along with the various levels of expression remarkably in BnEXP4 and BnRAB28, especially at 24 h of being sown under salt stress, which promoted seed germination and early seedling growth. Overall, this work provides new insights into mechanisms underlying the interactions of SeNPs and ZnONPs with plant hormones during the seed imbibition and early seedling stage, consequently enhanced plant growth and development. Additionally, these findings portrayed that the application of SeNPs and ZnONPs could be a new strategy and useful approach to enhance tolerance against salinity in rapeseed plants.

Microcosm Study on Allelopathic Effects of Leaf Litter Leachates and Purified Condensed Tannins from Kandelia obovata on Germination and Growth of Aegiceras corniculatum

Kandelia obovata (Ko) and Aegiceras corniculatum (Ac) are common and dominant plant species in mangrove wetlands in South China, which are distributed in similar tidal zones along the coastline. The present study aimed to determine the allelopathic effects of leaf litter leachates (LLLs) from Ko and their purified condensed tannins (PCTs) on the germination and growth of Ac by mangrove microcosms. Replicate pots containing five different levels of LLLs and PCTs were separately prepared and propagules of Ac were placed in each treatment. Both LLLs and PCTs significantly inhibited the germination and growth of Ac, especially at high concentrations. The final germination rates of the roots and stems and the numbers of fine roots declined continuously, while other growth indicators, including the lengths of fine roots and nutritive roots and the biomasses of roots, stems, and leaves first increased and then decreased with increasing levels. These results indicate that LLLs from the leaf litter of Ko, in particular their PCTs, exerted an inhibition effect on propagule germination and seedling growth of Ac, and the inhibitory effects were concentration dependent. This study suggested that condensed tannins from leaf litter, acting as allelochemicals, could regulate the natural regeneration of a mangrove forest.

Local conditions effects on seed germination of Hypericum balearicum L. in response to temperature

Temperature, which is one of the most relevant abiotic factors affecting seed germination, is strongly influenced by local site conditions. Here, we collected seeds of Hypericum balearicum, an endemic shrub of the Balearic Islands, from 11 sites of Mallorca. We investigated variations in final germination percentage (FGP), germination rate (t50) and germination timing (t0) of seeds from different provenances according to the local conditions of each location (here classified in mountain, coast and valley environment) under a range of temperature treatments (12–24 ºC). An environmental data logger was installed in three of the sites to determine the temperature variability for each environment. Hypericum balearicum germinates in the optimal temperature range of Mediterranean plants. FGP was neither affected by temperature treatments nor by the site of origin (environment). However, the coast environment showed higher t50 and t0 values in all temperatures tested compared to mountain and valley, especially at low temperatures compared to mountain environment and at low and high temperatures compared to valley environment. These differences among environments were consistent with the temperature parameters recorded in each environment. Overall, this study demonstrates the importance of taking into account local temperature conditions effects in germination in order to know how plants will respond to environmental changes.