Phytochrome-mediated photocontrol of the germination of the scentless mayweed, Matricaria inodora L., and its sensitization by nitrate and temperature

The emergence of Matricaria inodora (M. perforata) may poorly respond to modified light exposure during tillage. Therefore, the influence of light, nitrate and temperature on the germination of M. inodora has been studied under laboratory conditions. Germination of a native seed batch levels off around 77% after 7 to 9 days at 20°C, if sown in 0.01 M KNO₃ or NaNO₃ with a daily photoperiod of 14 h weak white light. In 0.01 M NaCl or in bidistilled water germination reaches 48 ± 5%. One saturating red-light pulse, applied 12 h after imbibition in 0.01 M KNO₃, gives only 12 ± 3% germination after 7 days, but 5 daily repeated red-pulses produce 75% germination. Ten twofold daily repeated red-light pulses are equivalently efficient, and if all immediately followed by a saturating far-red pulse, perfect reversibility down to the far-red level of 7 ± 3% germination is found. The dark germination was 1.7 ± 0.7%.

A fluence-response curve, elaborated for 10 red-pulses, gives an exponential pattern with half-saturating pulse fluence around 35 J m⁻², as indicative of phytochrome photoconversion. The influence of additional temperature pretreatment in darkness was tested, followed by half-saturating red-light pulses every 12 or 24 h. Chilling at 2 °C was ineffective up to 6 days, but slightly sensitizing after 21 days, giving around 30% and 46% germination, respectively. Preincubation for 6 days between 20 and 36 °C was more efficient and led to 58–68% germination at 20 °C. A thermoperiodic pretreatment with daily 12 h at 10 °C and 12 h at 30 °C was most efficient, giving 73 ± 4% germination. For all these pretreatments dark germination never exceeded 3%.

Elevated dark germination occurred when water-imbibed achenes, being exposed and dried in red-light of 1 W m⁻², have been reimbibed in darkness. If drying in red-light was for 6 h to a water content of 20% and reimbibition was in water or 0.01 M KNO₃, dark germination increased to 22 ± 5% or 40 ± 6%, respectively. This dark germination was far-red reversible down to 5 ± 2% with half-escape time around 5 h. If drying in red-light was for 24 h to reach the storing content of water around 11%, the dark germination after reimbibition in water or 0.01 M KNO₃ was only 4 ± 2% and 13 ± 2%, respectively. All corresponding controls for drying and reimbibition in darkness, for both water and nitrate, never exceeded 1% germination. This means that drying of seed in light — but not in darkness — increases emergence after the next rainfall and that the nitrate ion acts as a sensitizer for preformed P_fr and facilitates phytochrome-mediated germination.

Thus, for maximum germination of surface exposed M. inodora a thermoperiodic pretreatment, daily repeated light exposures and nitrate are needed. This is typical of the shallow germinating ancestor occurring in coastal ranges, the Sea Mayweed, Tripleurospermum maritimum, and may explain why the emergence of M. inodora is scarcely reduced after lightless tillage.     

Biogenic Nanoparticle-Mediated Augmentation of Seed Germination,Growth, and Antioxidant Level of Eruca sativa Mill. Varieties

A study was undertaken to examine the influence of biogenic nanoparticles synthesized from Tridax procumbens on different parameters of seed germination, seedling growth, and various biochemical parameters in four Eruca sativa varieties having low percentage of germination. Seeds were treated with different concentrations (30 and 40 ppm) of biogenic nanoparticles, of which 30 ppm was found to be the most effective and was therefore used for subsequent studies. Initially, the effect of biogenic nanoparticles on germination percentage, speed of germination, coefficient of germination, mean germination time, shoot and root length, fresh and dry matter, and vigor index was studied. From the experiments performed and the results obtained, it was evident that the treatment with biogenic nanoparticles decreased the electrolyte leakage and level of malondialdehyde as compared to control. The treatment with biogenic nanoparticles enhanced the levels of proline and ascorbic acid and stimulated the antioxidant enzyme activities resulting in the reduced level of reactive oxygen species. These activities were found to be variety-dependent. The possible involvement of biogenic nanoparticles in the production of new pores in seed coat during their penetration, resulting in the influx of the nutrients inside the seed, is suggested. This accelerated seed germination is followed by rapid seedling growth. The present findings indicated that biogenic nanoparticles promote seed germination in E. sativa by overcoming the detrimental effects of reactive oxygen species (ROS) and improving the antioxidative defense system which finally result in increased seedling growth.     

Effect of chemical and physical factors to improve the germination rate of Echinacea angustifolia seeds

Seeds of Echinacea angustifolia are known for their deep dormancy. In this paper, we studied the responses of E. angustifolia seeds to some chemical and physical factors, such as scarification, chilling (5 °C) period, light and applied BA (6-benzylaminopurine), GA₃ (gibberellic acid) and sound stimulation. When the seed coat layers were removed, the germination rate grew up from 6 to 20% (incubated in light) and the mean time germination (MTG) was reduced from 18 to 6.6 days. On the basis of layers-removed, chilling and continuous light gave significantly higher germination rate (up to 70%). Compare the data of seeds chilled by 0, 6, 12, 18 and 24 days, the maximum germination rate (up to 70%) achieved at 18-days chilling treatment. Further increases in the chilling period could slightly improve germination. Exogenous application of 0.1, 0.2, 0.3 mg/L GA₃ or BA in the previous pretreatment increased germination to 78, 90 and 84% or 76, 86 and 84%, respectively. Obviously, the best concentration of GA or BA is 0.3 mg/L. And the GA₃ or BA treatment shortened the MTG to about 4 days. The influence of sound stimulation was also tested in the experiment. The result showed that one 100 dB and 1000 Hz sound wave (sine-wave) was beneficial to the germination of E. angustifolia seeds.     

Effects of Saline-Alkaline Stress on Seed Germination and Seedling Growth of Sorghum bicolor (L.) Moench

In order to study the adaptation ability of sweet sorghum (Sorghum bicolor L. Moench) in the Yellow River Delta, the sweet sorghum variety Mart was used in this study to determine the roles of different saline-alkaline ratio stress treatment during seed germination to seedling stage. The results showed that Na⁺ concentration had a significant impact on the seed germination, seedling growth, and plant survival of sweet sorghum. Increasing Na⁺ concentration led to a decline in germination rate, final germination percentage, survival percentage, plant height, and dry weight per plant, a prolonged mean time of germination, as well as loss of improvement effect of low-Na+ concentration. The interaction effect of Na⁺ concentration and pH on the mean time of germination and germination rate was not significant (p?+ concentration (100 mM), high pH reduced the mean time of germination and increased the germination rate, without decline in final germination percentage and survival percentage. Therefore, at least in the duration of seed germination to the harvest period in the research, the sweet sorghum was resistant to the pH stress (≥9.04) when the Na⁺ concentration was below 100 mM. When suffered from the saline-alkaline stress, the seedling of sweet sorghum was characterized by ecological adaptive features, such as decreased stem ratio and chlorophyll b content in leaves and increased root ratio and chlorophyll a content, in order to maintain the uptakes of water and nutrient, and carbon assimilation. When the stress intensified, the lipid oxidation products, e.g., malondialdehyde (MDA), increased in sweet sorghum seedlings. However, the increasing of soluble protein content and antioxidant enzyme activity (superoxide dismutase (SOD), guaiacol peroxidase (POD), and gatalase (CAT)) was only founded in neutral low-Na⁺ concentration treatment (A₁), which indicated that high-salt concentration and pH all elicited harmful effects and limited the self-healing ability of sweet sorghum seedlings. In all, in order to grow sweet sorghum in the saline-alkaline soils of the Yellow River Delta, the salt concentration and pH value of the soil must be taken into consideration, and seeding density should be increased and supported by appropriate irrigation measures to reduce saline-alkaline stress so as to ensure the survival and growth of sweet sorghum seedlings.     

铈对酸雨胁迫下大麦种子萌发的影响

研究了铈对酸雨胁迫大麦种子萌发的影响,随着雨ｐＨ值的增加,大麦发芽势,发芽率、幼苗地下与地上部干重及叶绿素含量递减,根系质膜透性递增;酸雨对铈浸种的大麦种子的胁迫作用减轻,表明有缓解酸雨胁迫种子萌发的作用。     

种子萌发生长的微量热及非平衡热力学研究

生命系统中发生的许多过程都有放热和吸热现象.人们对于生命过程的热现象进行了很多研究.对于植物生长的能量效应研究也做了一些工作[1—4].种子萌发生长的热释出是植物产热的一个很好例子,在种子萌发生长过程中伴随着物质和能量的转化,用微量热法测定种子萌发生长热谱并解析这些热谱,将有助于我们认识种子萌发生长机理及其影响因素.Ｐｒａｔ等人曾对小麦、玉米及一些蔬菜种子的萌发生长进行过较为系统的研究[1,2].他们的工作为用量热法研究植物产热开辟了道路.但由于当时测量技术与仪器设计的限制,其研究结果是粗糙的,且与种子萌发的实际情…     

Effects of Oxygen (O2) Plasma Treatment in Promoting the Germination and Growth of Chili

In general, seed germination is improved by low-pressure plasma treatment using precursors such as air, nitrogen, O_2, and argon, etc. For the first time, low-pressure O₂ plasma was used to treat chili seeds in this study. When compared to untreated and vacuum-treated seeds, O₂ plasma treatment using the discharge power of 80 W for 60 s significantly improves chili seed germination and growth. The effect of vacuum on the germination and growth of chili seeds was also studied and shown to be negligible. The physical and chemical changes induced by O₂ plasma treatment were investigated to understand the plasma treatment to germination improvement. Combinatory etching and chemical modification aided imbibition and increased germination percentage in this O₂ plasma treatment on chili seeds. The success of this method has the potential to be scaled up to solve food security issues with seeds that would otherwise struggle to germinate.

     

Effect of γ-ray irradiation on the germinating characteristics of wheat seed

Few researches have been reported on the long-term germination characteristics and the effect of high gamma radiation dose on cereal seeds. In this paper, to observe the effects of gamma irradiation (0-3 kGy) on the germination of wheat seed in long-term (within 20 months), wheat seed was dried after irradiation and the germination experiment during storage time was conducted. It was found that the lengths of buds of irradiated wheat seeds diminished, the roots of irradiated wheat seeds disappeared, and no germinations in irradiated wheat seed was found. The influence of γ-ray irradiation on roots was more significant than that on buds. After long-term storage, the germination of irradiated wheat seeds increased.     

PHYTOCHROME-MEDIATED GERMINATION: EFFECTS OF BRIEF HIGH TEMPERATURE TREATMENTS

Abstract— Brief high temperature treatments, applied early in the pregerminative period to radiation-requiring seeds of lettuce, inhibited both dark and radiation-induced germination. The inhibition increased with increasing incubation temperature. There was little difference in the germination percentage whether the inductive irradiation was applied before or after the high temperature treatment. When the high temperature treatment preceded induction, there was an increase in the radiation dosage required for maximum germination. These findings are interpreted in terms of lability of physiologically active phytochrome to higher temperatures.     

CHANGES IN ULTRAVIOLET RESISTANCE AND PHOTOPRODUCT FORMATION AS EARLY EVENTS IN SPORE GERMINATION OF BACILLUS CEREUS T

Abstract— In order to determine the timing of the change in the state of DNA in bacterial spores during the course of germination, L-alanine-induced germination of Bacillus cereus spores was interrupted by 0.3 M CaCl₂ as an inhibitor, and the resulting semi-refractile spores (spores at the end of the first phase of germination) were examined on the UV-resistance and the photoproduct formation.
Upon UV-irradiation, these spores, still having a semi-refractile core as observed under a phase-contrast microscope, gave rise to mainly the cyclobutane-type thymine dimer. It was concluded that change in the state of the spore DNA occurs early in the process of germination, i.e. before the refractility of the core was lost.
It was also found that CaCl₂ markedly prolonged the duration of the transient UV-resistant stage.     

玉米秸秆/羧甲基纤维素复配水凝胶水分释放行为

以粉碎的玉米秸秆(RCS)和羧甲基纤维素(CMC)为原料,制备了含水质量分数可达97.47%的玉米秸秆/羧甲基纤维素复配水凝胶(RCS/CMC)。考察了交联剂、CMC和RCS用量对RCS/CMC凝胶模量的影响,凝胶在缓冲溶液中的降解行为和土壤中的失重行为,以及凝胶对土壤持水量、玉米种子萌发的影响。结果表明,与对照实验比较,RCS/CMC凝胶可以提高土壤持水率1.00%~1.61%,在37 ℃缓冲溶液中用纤维素酶处理4 d后降解率约80%,土壤中25 d后失重约94%;用CMC/RCS凝胶处理玉米种子,虽然平均延长了种子萌发时间,但种子的萌发率较高。其中相对湿度18%、20%、23%、26%、28%和30%的萌发试验,由于水分胁迫对照实验种子不能萌发,而CMC/RCS凝胶处理的种子发芽率仍可达到97%。     

Impact of Short Time Atmospheric Plasma Treatment on Onion Seeds

The paper presents the results of an experiment on the effect of cold plasma (He?+?O₂ and He?+?Air) generated in a radio frequency cold atmospheric plasma jet on the process of germination of onion cv. Wolska (Allium cepa L.) seeds. In order to determine the impact of the gas flow on the seed surface, CFD simulations and Schlieren imaging were performed and surface characteristics were studied using a digital microscope. Plasma treatment of the seeds was carried out four times (2, 5, 10 and 15 s) with one control group. Pre-sowing plasma stimulation of seeds improved the germination capacity and germination energy for all tested groups in comparison to the control. The best germination capacity and energy were obtained for seeds stimulated with 10 s of plasma treatment. Analysis of the data showed a statistically significant impact of plasma treatment on the onion seed’s germination parameters. Plasma treatment did not induce significant changes on the seed surface, as microscope images showed but length of all plasma-treated seedlings increased in comparison to control.

     

Air Atmospheric Dielectric Barrier Discharge Plasma Induced Germination and Growth Enhancement of Wheat Seed

Air atmospheric dielectric barrier discharge plasma (DBD) was attempted to pretreat wheat seed to improve its germination and growth in this study. The effects of the DBD plasma treatment on the wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation level, and antioxidant enzymes activity were investigated. The experimental results showed that the DBD plasma treatment with an appropriate time scale could promote the wheat seed germination and seedling growth. The germination potential, germination rate, germination index, and vigor index increased by 26.7, 9.1, 16.9, and 46.9% after 7 min’s DBD plasma treatment, respectively; the root length, shoot length, fresh weight, and dry weight of the seedlings also increased after the DBD plasma treatment. The osmotic-adjustment products, proline and soluble sugar contents, in the wheat seedlings were significantly enhanced after the DBD plasma treatment with an appropriate time scale, while the malondialdehyde content decreased. Moreover, the activities of superoxide dismutase and peroxidase also increased after the DBD plasma treatment. The DBD plasma treatment led to etching effect on the wheat seed coat, resulting in the improvement of its water absorption capacity.     

Chemical composition and herbicidal activity of the essential oil from a Cistus ladanifer L. population from Spain

The essential oil composition of Cistus ladanifer grown in central Spain was analysed by gas chromatography and gas chromatography/mass spectrometry, revealing it to be rich in oxygenated compounds, with trans-pinocarveol (20.00%), bornyl acetate (7.03%) and terpinen-4-ol (6.37%) as the main monoterpene compounds. Viridiflorol (13.59%) and ledol (4.36%) were the main constituents of the oxygenated sesquiterpene fraction. Large amounts of α-pinene (4.70%) were found in the hydrocarbonated fractions. To study its possible use as a natural herbicide, the oil was tested in?vitro against Amaranthus hybridus, Portulaca oleracea, Chenopodium album, Conyza canadensis and Parietaria judaica, completely inhibiting A. hybridus germination, and nearly blocking C. canadensis and P. judaica germination at all concentrations assayed. In P. oleracea, the oil showed less effect, inhibiting its germination at the higher doses studied. It did not control C. album germination. Regarding seedling length, the oil had strong phytotoxic activity, being effective at all concentrations tested.     

THE TEMPERATURE DEPENDENCE OF Pfr ACTION GOVERNS THE UPPER TEMPERATURE LIMIT FOR GERMINATION IN LETTUCE

In most cultivars of lettuce (Lactuca saliva L,), red light acting through the red/far-red reversible phytochrome system promotes full germination within the20–30°C range, but at progressively higher temperatures germination declines sharply. The relationship between this upper ternperature limit for germination and the temperature dependence of phytochrome action was investigated in Grand Rapids lettuce. In fresh seeds the GT₅₀ (temperature giving half maximal germination) was ca 29–30°C. In these seeds, escape from far-red reversibility did not occur at 35°C, a temperature above the GT₅₀, but occurred rapidly at 27°C, a temperature below the upper limit. Increasing periods of dark pretreatment at high temperature (35°C) or increasing concentrations of the germination inhibitor coumarin caused a progressive decline in the GT₅₀, Escape from photoreversibility did not occur at 27°C in seeds in which the GT₅₀ had been reduced to less than 25°C by coumarin or by prolonged high temperature pretreatment. These results indicate that there is a close correlation between the position of the upper temperature limit for germination, and the temperature dependence of phytochrome action. We conclude that factors that alter the upper temperature limit for germination do so by changing the temperature dependence of phytochrome action.     

NITRATE EFFECT ON Pfr-MEDIATED AND GA3-INDUCED GERMINATION IN SPORES OF Anemia phyllitidis (L.) Sw*

Spore germination in Anemia phyllitidis can be induced by red light (R) via the phytochrome system and by gibberellic acid (GA₃) in the dark. An enhancing effect of NO₃-ions on the Pfr-mediated germination could be demonstrated. This NO₃-effect was found to be pronounced during the preinduction phase and could be described by biphasic kinetics depending on the formation of Pfr by the R-irradiation. Besides NO₃, other electron accepting substances also increased germination significantly. In contrast to Pfr-mediated germination, no enhancing effect by NO₃ could be obtained for the GA₃-induced germination response. The application of an inhibitor of gibberellic acid synthesis, AMO1618, as well as the analysis of combined R and GA₃ treatment, support the hypothesis that for germination of Anemia phyllitidis spores no synergism between the factors exists. Thus, it is proposed that the gibberellic acid receptor starts a signal-transduction pathway resulting in germination which is in part independent of the Pfr-mediated signal-transduction chain. The NO₃-effect is specific for the Pfr-mediated signal-transduction chain.     

Study of allelopathic effects of Eucalyptus erythrocorys L. crude extracts against germination and seedling growth of weeds and wheat

Allelopathic materials inside a tree can produce positive or negative change in the survival, growth, reproduction and behaviour of other organisms if they escape into the environment. To assess these effects, this work was carried out to evaluate the allelopathic impact of Eucalyptus erythrocorys L. on seed germination and seedling growth of two weeds: Sinapis arvensis L. and Phalaris canariensis L.; on one cultivated crop: Triticum durum L. Aqueous; and on ethanolic leaf extracts of E. erythrocorys L. The study was effected using four concentrations (10, 20, 25 and 30 μL/mL) while distilled water was used as a control. The results showed that the E. erythrocorys L. crude extracts had an inhibitory effect on seed germination and seedling growth of both studied weeds and wheat. The inhibition rate was increased by the increase in extract concentration. Only ethanolic extracts of E. erythrocorys L. induced a significant inhibition of seed germination of durum wheat. The effect of E. erythrocorys L. crude extracts was more severe on weeds than on durum wheat. These results indicate that the seedling growth, especially radicle elongation, was the more sensitive indicator to evaluate the effects of extracts than was the seed germination.     

Rhizonin A from Burkholderia sp. KCTC11096 and its growth promoting role in lettuce seed germination

We isolated and identified a gibberellin-producing Burkholderia sp. KCTC 11096 from agricultural field soils. The culture filtrate of plant growth promoting rhizobacteria (PGPR) significantly increased the germination and growth of lettuce and Chinese cabbage seeds. The ethyl acetate extract of the PGPR culture showed significantly higher rate of lettuce seed germination and growth as compared to the distilled water treated control. The ethyl acetate fraction of the Burkholderia sp. was subjected to bioassay-guided isolation and we obtained for the first time from a Burkholderia sp. the plant growth promoting compound rhizonin A (1), which was characterized through NMR and MS techniques. Application of various concentrations of 1 significantly promoted the lettuce seed germination as compared to control.     

Growth and production of buckwheat (Fagopyrum esculentum) treated with reduced, ambient, and enhanced UV-B radiation

The effect of enhanced UV-B radiation on buckwheat (Fagopyrum esculentum Moench. variety 'Darja'), an important high elevation crop, was studied in order to estimate its vulnerability in changing UV-B environment. Plants were grown in outdoor experiments from July to October under reduced and ambient UV-B levels, and an UV-B level simulating 17% ozone depletion in Ljubljana. During the development the following parameters were monitored: light saturated photosynthetic activity, transpiration, potential and effective photochemical efficiencies of photosystem II, the contents of photosynthetic pigments and methanol soluble UV-B absorbing compounds. At the end of the experiment, growth rate and production of seeds were estimated. In the following growth season the seeds collected from plants exposed to different UV-B treatments were tested for germination capacity. Total UV-B absorbing compounds during plant development were increased by UV-B radiation, photosynthetic pigments (chlorophyll a and b and carotenoids) decreased. Photosynthetic rate was lowered in an early stage of development. UV-B treatment resulted in the increase in the transpiration rate and consequently the decrease in water use efficiency (WUE). The disturbances in water economy and in photosynthesis affected the reproduction potential negatively; the production of seeds in plants cultivated under ambient and enhanced UV-B was 57 and 39% of the production of specimens treated with reduced UV-B, respectively. The germination of seeds collected from treated plants revealed on average about 95% success, independently of the treatment, but the time needed for germination was the shortest for seeds developed under enhanced UV-B level treatment. Enhanced UV-B radiation affected water relations and production of buckwheat, but not the potential of seeds for germination.     

Light quality influences indigo precursors production and seed germination in Isatis tinctoria L. and Isatis indigotica Fort

Isatis tinctoria L. and Isatis indigotica Fort. are biennial herbaceous plants belonging to the family of Cruciferae that are used as a source of natural indigo and show several morphological and genetic differences. Production of indigo (indigotin) precursors, indican (indoxyl beta-D glucoside) and isatan B (indoxyl ketogluconate), together with seed germination ability were compared in Isatis tinctoria and Isatis indigotica grown under six different light conditions (darkness, white, red, far red, blue, yellow light) at 25 degrees C. Light quality influenced both germination and production of indigo precursors in the two Isatis species. Different responsiveness to far red and blue light was observed. Indeed, a detrimental effect on germination by blue and far red light was found in I. tinctoria only. Different amounts of isatan B were produced under red and far red light in the two Isatis species. In I. tinctoria, the level of main indigo precursor isatan B was maximal under red light and minimal under far red light. Whereas in I. indigotica far red light promoted a large accumulation of isatan B. The photon fluence rate dependency for white and yellow light responses showed that the accumulation of indigo precursors was differently influenced in the two Isatis species. In particular, both white and yellow light enhanced above 40 micromol m(-2) s(-1) the production of isatan B in I. indigotica while only white light showed a photon fluence dependency in I. tinctoria. These results suggest a different role played by the labile and stable phytochrome species (phyA and phyB) in the isatan B production in I. tinctoria and I. indigotica. I. indigotica, whose germination percentage was not influenced by light quality, demonstrated higher germination capability compared with I. tinctoria. In fact, I. tinctoria showed high frequency of germination in darkness and under light sources that establish high phytochrome photoequilibrium (red, white and yellow light). Germination in I. tinctoria was negatively affected by far red and blue light. I. indigotica seeds appear to be indifferent to canopy-like light (far red). Our results provide further insights on the distinct behaviour of I. tinctoria and I. indigotica that belong to two different genetic clusters and different original environments.