The biological effect of extremely low frequency electromagnetic fields and vibrations on barley seed hydration and germination

The changes of wet and dry weights and germination of barley seed in different periods of its swelling in nontreated (control), extremely low frequency electromagnetic fields (ELF EMF) )-treated, and extremely low frequency vibrations (ELFV)-treated cold (4 degrees C) and warm (20 degrees C) distilled water (DW) were studied. The metabolic-dependent seed hydration, dry weight dissolving, germination, and water binding in seed were modulated by preliminary EMF- and ELFV-treated DW. Frequency "windows" for the effect of EMF and ELFV on seed hydration, solubility, water binding in seed, and germination were discovered. These "windows" were different for EMF and ELFV, as well as in various phases of seed swelling. It is suggested that EMF-induced water structure modification has a different biological effect on the process of seed hydration, solubility, water binding in seed, and germination compared to ELFV.     

The influence of a low- and high-frequency electromagnetic fields on seeds

It was shown that the exposure of seeds in the rest phase to a low-frequency pulse electromagnetic field leads to substantial changes in seed physiology during germination. The changes at the physiological level in sprouting seeds depend not only on the frequency of the external EMF and its power characteristics but also on the kind of seeds. Low- and high-frequency electromagnetic fields are able to produce a biostimulation effect; however, the mechanisms of its appearance are different in their nature. The biochemical studies of seeds after EMF treatment in the modes resulting in expressed biological effects showed an increase in the activity of alpha-amylase, which testifies an increase in the gibberellin output and in the activity of the hydrolytic enzyme sour phosphatase. The response of seeds to EMF treatment demonstrates the possibility of electromagnetic control of growth processes.     

Physiological responses of Plantago media to electromagnetic field of power-line frequency (50 Hz)

Experimental evidence is presented that continuous exposure of hoary plantain (Plantago media L.) seedlings to the electromagnetic field (EMF) of power-line frequency may disturb physiological, biochemical, and cytological characteristics of these plants. The increase in EMF strength in the range from 230 to 1800 V/m (350–2000 nT) was found to reduce the percentage of seed germination, the rate of cell division, and the rates of DNA and protein biosyntheses in tissues of 8-day-old seedlings. The action of EMF with the strength of 500–1000 V/m (800–1150 nT) stimulated root growth, elevated the content of malondialdehyde and low-molecular antioxidants, and enhanced the activity of superoxide dismutase. Direct correlation was revealed between lipid peroxidation rates and the activity of cellular antioxidant defense system. The wavelike changes in the content of photosynthetic pigments were observed in plantain seedlings exposed to EMF of various strengths.     

Germination and infectivity of ectomycorrhizal fungal spores in relation to their ecological traits during primary succession

The spores of ectomycorrhizal fungi (EMF) play critical roles in the population and community development of EMF. Here, the germination and infectivity of EMF spores are examined with reference to the ecological traits of the EMF species. Spores were collected from 12 EMF species, whose successional patterns have been studied in the volcanic desert on Mount Fuji, Japan. Spore germination experiments were conducted with host plants (Salix reinii), with nonhost plants (Polygonum cuspidatum), and without plants. The mycorrhizal formation ability of spores was also examined in seven EMF using spore inoculation experiments. To determine the effects of the spore preservation period, both experiments were repeated up to 1 yr after spore collection. Spore germination was very low in the absence of host plants. In the presence of hosts, even 30 d after spore collection, spore germination was significantly enhanced in all pioneer EMF (c. 20%) but less so in late-stage EMF (< 5%), except in Hebeloma species. Mycorrhizal formation from spores was also greater in pioneer EMF but was significantly reduced by 1 yr of spore preservation. High spore germination and infectivity of pioneer EMF should enable these species to colonize disturbed and isolated areas in accordance with their ecological traits.     

On the modulation effect of pulsing and static magnetic fields and mechanical vibrations on barley seed hydration

The changes of wet and dry weights of barley seed in different periods of swelling were studied in seeds treated with Extremely Low Frequency Electromagnetic Fields (ELF EMF), Static Magnetic Fields (SMF) and Mechanical Vibrations (MV) in cold (4 degrees C) and warm (20 degrees C) distilled water as well as in seeds non-treated (control). The metabolic dependent seed hydration, dry weight loss and water binding in seed were modulated by preliminary EMF, SMF and MV-induced treatment of distilled water. The specific electrical conductivity (SEC) of control and treated distilled water was measured before the seed incubation. Frequency and intensity "windows" (i.e. range of frequency or intensity) for the effect of EMF, MV and SMF (correspondingly) on seed hydration, solubility and water binding in seed were studied. These "windows" were different in various phases of seed swelling. It is suggested that water structure modification is the result of valence angle changes (SMF and EMF) and dipole molecules vibration (EMF and MV) has different effects on the process of hydration, solubility and water binding in seed. These results are important from the point of understanding the mechanisms of the biological effect of EMF, as well as from the point of agriculture.     

Seed size and seed germination in the Mediterranean fire-prone shrub <Emphasis Type="Italic">Cistus </Emphasis><Emphasis Type="Italic">ladanifer</Emphasis>

The germination response of different sized seeds from individuals of a Mediterranean fire-prone shrub (Cistus ladanifer) was investigated in relation to pre-germination heating. A control (no heating), a low temperature during a short exposure time (50°C during 5 min), a high temperature during a short exposure time (100°C during 5 min) and a high temperature during a long exposure time (100°C during 15 min) were applied to seeds from different individual plants with different mean seed weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire, low intensity pasture fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Mean seed weight only showed a marginally significant positive correlation with the proportion of germinated seeds whatever the pre-germination treatment. These results suggest that seed dormancy is unrelated to seed size and that under the experimental conditions used in this study, the effect of seed size on seed germination is low. Nevertheless, larger seeds could be favoured in natural conditions, especially under the high competition scenario which arise after wildfires. Control seeds showed a negative correlation between seed size and germination velocity suggesting that lighter seeds could take advantage from early germination in recruitment events in the absence of wildfires. Nevertheless, even the lower pre-germination heating treatment turns this correlation in not significant, suggesting a strong selection pressure (unrelated to seed size) for early germination after fire events. In our study, different sized seeds of C. ladanifer seem to perform better under different germination scenarios suggesting that seed size variation could be maintained by the alternation of recruitments without wildfires and recruitments after wildfire events.     

Evaluation of chemical seed coat sterilants

Summary Three seed coat sterilants were evaluated for effectiveness as surface sterilants and for effects on seed germination. Several exposure times in sodium hypochlorite, hydrogen peroxide and peracetic acid were evaluated. Seeds of the following crop plants were used: wheat (Triticum aestivum L.); sorghum [Sorghum bicolor (L.) Moench]; soybean [Glycine max (L.) Merrill]. All treatments reduced germination of wheat and soybean seed, but only the most severe peracetic acid treatments substantially reduced germination of sorghum seed. Considering both sterilization effectiveness and seed germination, a treatment with 5% sodium hypochlorite for 45 min appeared to be the most satisfactory of the treatments used.     

Acute and chronic ozone exposure temporarily affects seed germination in alpine plants

This study was the first to investigate the direct effects of anomalous concentrations of ozone mediated by summer heat waves on seed germination in alpine plants. During germination, the seeds were exposed to three peaks of O₃ concentration (125 ppb for 5 and 10 days; 185 ppb for 5 days), derived from measurements taken close to the species growing site. High O₃ concentration delayed the first germination time, increased the mean germination time, and reduced the germination percentage during and immediately after the treatment, but, in most cases, effects were weak and had almost vanished three weeks after the treatments. In few cases, chronic exposure to O₃ (125 for 10 days’ treatment) enhanced seed germination compared to the control, suggesting that ozone may induce antioxidant and DNA-repair mechanisms or dormancy-breaking effects in hydrated seeds. Although seed mortality increased during O₃ treatments in four species, the effect of O₃ on seed germination is mostly limited to the period of exposure, indicating that it is unlikely to produce permanent negative effects on seeds, during the germination phase. Our results show that the direct effect of O₃ on seeds of alpine plants may have minor impacts on plant reproductive performance during seed germination.     

High salinity impacts germination of the halophyte Cakile maritima but primes seeds for rapid germination upon stress release

Seed germination recovery aptitude is an adaptive trait of overriding significance for the successful establishment and dispersal of extremophile plants in their native ecosystems. Cakile maritima is an annual halophyte frequent on Mediterranean coasts, which produces transiently dormant seeds under high salinity, that germinate fast when soil salinity is lowered by rainfall. Here, we report ecophysiological and proteomic data about (1) the effect of high salt (200 mM NaCl) on the early developmental stages (germination and seedling) and (2) the seed germination recovery capacity of this species. Upon salt exposure, seed germination was severely inhibited and delayed and seedling length was restricted. Interestingly, non‐germinated seeds remained viable, showing high germination percentage and faster germination than the control seeds after their transfer onto distilled water. The plant phenotypic plasticity during germination was better highlighted by the proteomic data. Salt exposure triggered (1) a marked slower degradation of seed storage reserves and (2) a significant lower abundance of proteins involved in several biological processes (primary metabolism, energy, stress‐response, folding and stability). Yet, these proteins showed strong increased abundance early after stress release, thereby sustaining the faster seed storage proteins mobilization under recovery conditions compared to the control. Overall, as part of the plant survival strategy, C. maritima seems to avoid germination and establishment under high salinity. However, this harsh condition may have a priming‐like effect, boosting seed germination and vigor under post‐stress conditions, sustained by active metabolic machinery.     

Effect of light on seed germination of eight wetland Carex species

BACKGROUND AND AIMS: In wetland plant communities, species-specific responses to pulses of white light and to red : far-red light ratios can vary widely and influence plant emergence from the seed bank. Carex species are the characteristic plants of sedge meadows of natural prairie wetlands in mid-continental USA but are not returning to restored wetlands. Little is known about how light affects seed germination in these species-information which is necessary to predict seed bank emergence and to develop optimal revegetation practices. The effects of light on germination in eight Carex species from prairie wetlands were investigated. METHODS: Non-dormant seeds of eight Carex species were used to determine the influence of light on germination by examining: (a) the ability of Carex seeds to germinate in the dark; (b) the effect of different lengths of exposures to white light on germination; (c) whether the effect of white light can be replaced by red light; and (d) whether the germination response of Carex seeds to white or red light is photoreversible by far-red light. KEY RESULTS: Seeds of C. brevior and C. stipata germinated >25 % in continuous darkness. Germination responses after exposure to different lengths of white light varied widely across the eight species. Carex brevior required <15 min of white light for > or =50 % germination, while C. hystericina, C. comosa, C. granularis and C. vulpinoidea required > or =8 h. The effect of white light was replaced by red light in all species. The induction of germination after exposure to white or red light was reversed by far-red light in all species, except C. stipata. CONCLUSIONS: The species-specific responses to simulated field light conditions suggest that (a) the light requirements for germination contribute to the formation of persistent seed banks in these species and (b) in revegetation efforts, timing seed sowing to plant community development and avoiding cover crops will improve Carex seed germination.     

Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes

The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three salt-marsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and management.     

Desiccation,Moisture Content and Germination of Zostera marina L. Seed

Zostera marina is the only seagrass species whose seeds have been successfully used in large‐scale restoration. Although progress has been made in refining Z. marina restoration protocols, additional information on Z. marina seed physiology is necessary as the science of seagrass restoration evolves. We tested the germination rates of Z. marina seeds under different relative humidities and temperatures for different periods of time. Z. marina seed moisture content (MC) and germination rates were also tested when seeds were exposed to a temperature of 25°C and relative humidity of 50%. Z. marina seeds suffered higher mortality when exposed to lower relative humidity and higher temperature for longer period of exposure time. A significant negative correlation was detected between seed germination rate and MC. Z. marina seeds are sensitive to desiccation exposure and long periods of exposure to air should be prevented to minimize seed mortality when seeds are used in restoration projects.     

Species‐specific germination responses to fire‐associated heat of elephant‐dispersed seeds in Nimule National Park,South Sudan

Fire‐related heat and endozoochory by elephants have independently been found to be important for savanna plant seed germination, yet there is little information on how heat affects germination of elephant‐dispersed seeds. We measured the germination behavior (time to germination and proportion of seeds germinating) of 11 species of seeds extracted from African savanna elephant dung and subjected them to various intensities of heat as a proxy for fire exposure. The effects of heat were inconsistent and varied significantly by species, with some species having increased time to germination in response to heat and others having reduced time to germination. More studies are needed to expand the number of seed species examined and tease apart the interaction between elephant‐mediated endozoochory and fire.     

Brassinosteroid improves seed germination and early development of tomato seedling under phenanthrene stress

Polycyclic aromatic hydrocarbons (PAHs) are one of the toxic persistent organic pollutants, have global environmental concern. Seed germination and early seedling development are the initial handicaps for plant establishment in phytoremediation program. Assisted phytoremediation by plant growth regulators may be a potential solution for these problems. Hence, we investigated the effects of seed treatment with various concentrations (0.01, 1.0, 100?nM) of 24-epibrassinolide (EBR) in tomato under graded levels (30, 100, 300???M) of a three-ring PAH namely phenanthrene (PHE). Delayed and decreased seed germination, reduced length and fresh weight (FW) of shoot and root were observed following 10?days of PHE exposure in a dose dependent manner. Chlorophyll fluorescence study suggested a possible photoinhibition and damage to photosynthetic apparatus under PHE exposure. However, seed treatment with EBR improved seed germination and increased length and FW of shoot and root. In addition, EBR remarkably restored the studied chlorophyll fluorescence parameters towards control levels. Different responses in antioxidant enzymes were observed following PHE exposure, while malondialdehyde (MDA) content was increased in a concentration dependent manner. EBR treatment prior to PHE exposure remarkably increased the activities of antioxidant enzymes over PHE alone, but decreased the MDA contents both in shoot and root of young tomato seedlings. Considering all the studied parameters, seed treatment with 1.0?nM EBR was most effective followed by 100 and 0.01?nM for the improvement of germination and seedling growth under PHE stress in tomato.     

Intensity-time dependence dosing criterion in the EMF exposure guidelines in Russia

Major approaches of the Russian Federation in setting of exposure guidelines to electromagnetic fields (EMF) in occupational and public environments are discussed in this paper.

EMF exposure guidelines in Russia are based on the results of hygienic, clinical, physiological, epidemiological and experimental studies and are frequency-dependent. The concept of a threshold principle of occupational and environmental factors due to hazardous exposure effects has been used to set permissible exposure levels of different EMF frequency ranges. The data of experimental studies showed hazardous threshold levels of EMF effects. The main criteria of EMF hazardous exposure evaluated in the experimental study concerned both estimation of threshold levels of chronic (long-term) and acute exposure. Also, this paper contains some recent experimental study data on correlation of long-term radiofrequency and power-frequency EMF exposure effects with regard to time duration, the so-called time-dependence approach. It enables identification of the value of permissible EMF exposure levels depending on exposure duration. This approach is used in occupational exposure guideline setting and requires the introduction of “power exposition” (PE) and “maximal permissible level” (MPL). In general, EMF exposure guidelines are established with regard to possible duration of exposure per day.     

Influence of nutrient availability and tree wildling density on nutrient uptake by Oxalis acetosella and Acer saccharum

The different weight-number strategies of seed production displayed by individuals of a Mediterranean fire-prone plant species (Cistus ladanifer) were investigated in relation to seed germination responses to pre-germination heating. A control (no heating), a high temperature during a short exposure time (100 degrees C during 5 min) and a high temperature during a long exposure time (100 degrees C during 15 min) were applied to seeds from different individual plants with different mean seed weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Seed germination was related to heat treatments and seed mass. Seed heating increased the proportion of seeds germinating compared with the control treatment. Mean seed weight was positively correlated to the proportion of germinated seeds but only within heat treatments. These results suggest that in periods without fire, the relative contributions to the population dynamics are equal for all seeds, regardless of their mass, whereas heavier seeds would be the main contribution after wildfire events. Since lighter seeds can be produced in higher quantities than heavier ones within a given fruit, the number of seedlings produced per fruit depended strongly on the germination conditions. In the absence of wildfire, fruits producing lighter seeds gave rise to more seedlings; nevertheless, they were numerically exceeded by those producing heavy seeds after a wildfire. The implications of these results are discussed in relation to their consequences on the population dynamics of this species, considering also additional information on stand flammability and changes in seed mass with plant age.     

Effect of Extremely Low Power Time-Varying Electromagnetic Field on Germination and Other Characteristics in Foxtail Millet (Setaria italica) Seeds

The ability of extremely low, time-varying electromagnetic field (EMF) to improve germination efficacy was studied in Foxtail millet (Setaria italica) seeds using response surface methodology. An optimal factorial central composite design was chosen to optimize the EMF with three critical factors, viz. frequency, intensity, and duration. The adequacy of the model and fitness was evaluated by analysis of variance and regression coefficients. This model suggested that the factors, frequency, and intensity had a significant impact on germination. Optimal conditions for germination were observed to be 10 Hz frequency, 30,007 nT intensity, and 30-min duration with an observed germination percentage of 93.0, and a predicted germination percentage of 92.92. Magneto-priming was found to increase the germination efficacy (15.66%), shoot length (27.78%), total seedling length (20.30%), seedling dry mass (26.49%), and water uptake (34.48% at 80 min) showing significant output when compared with the control and positive controls. Remarkable improvements were observed in germination parameters such as vigor index-1 (39.14%), vigor index-2 (46.28%), speed of germination (27.52%), and emergence index (12.50%). Magneto-priming was found to reduce the levels of germination-specific enzymes, viz. α-amylase, protease, and dehydrogenase, while it enhanced the levels of antioxidant enzymes, viz. catalase (114.63%) and superoxide dismutase (19.62%), triggering fast germination and early vigor of seedlings. This study clearly showed that EMF priming significantly improved the germination effect and other characteristics of Foxtail millet seeds. Bioelectromagnetics. © 2020 Bioelectromagnetics Society     

Impacts of fire cues on germination of Brassica napus L. seeds with high and low secondary dormancy

• Agricultural burning is used in farm management operations; however, information about the impact of fire cues on the release and/or induction of secondary dormancy in crop seeds is scarce.
• Seeds from two oilseed rape cultivars were induced for high (HD) or low (LD) secondary dormancy using polyethyleneglycol (PEG) pre‐treatment, and their germination after exposure to various fire cues was compared to control PEG pre‐treated and non‐dormant seeds.
• Non‐dormant seed germination was unaffected by various fire cues. Low doses of aerosol smoke released secondary dormancy in HD seeds, while higher doses increased dormancy of LD seeds. Dilute smoke water also released HD seed secondary dormancy, but concentrated smke water enhanced dormancy in both LD and HD seeds. The concentrated aqueous extracts from charred oilseed rape straw only promoted germination of HD seeds, while dilution inhibited LD seed germination. Heat shock (80 °C, 5 min) released secondary dormancy in HD seeds; however, higher temperatures and/or increased exposure time was associated with seed death. GC‐MS analyses of smoke water revealed two butenolides and an array of monoaromatic hydroxybenzene compounds with potential germination inhibitor or promoter activity.
• The extent of secondary dormancy induction in seeds affects their subsequent responses to fire cues. Both aerosol smoke and smoke water have both germination promoter and inhibitor activity. Lacking any butenolides, aqueous extracts of charred straw contain a potential germination stimulating steroid, i.e. ergosterol. The significance of fire‐derived cues on behaviour of oilseed rape seeds in the soil seed bank is discussed.

     

EMF基因与植物营养生长

在高等植物中,外源和内源因素共同调控着植物从营养生长到生殖生长的转换。拟南芥EMF1和EMF2基因缺失的突变体不经过任何营养生长,种子萌发后便开花,这说明EMF基因是植物花发育的抑制基因。目前已从水稻、玉米、拟南芥等植物中克隆得到EMF同源基因,但其功能研究大多停留在拟南芥上。研究表明,EMF基因决定着植物营养生长阶段的发育,抑制植物开花。因此,开展EMF基因的分离、克隆和功能研究,有利于阐述植物营养生长过程阶段的抑花机制。对EMF基因的研究进展进行了综述,并提出EMF基因表达调控的闸门模型,以对EMF基因功能的进一步分析提供参考。