Quantal Response of Seed Germination in Seven Genera of Cruciferae to White Light of Varying Photon Flux Density and Photoperiod

The response of the germination of seeds of Barbarea vema (Mill.)Aschers, Brassica chinensis L., Brassica juncea (L.) Czern.& Coss., Brassica oleracea L. var. gongylodes L., Camelinasaliva (L.) Crantz, Eruca saliva Mill., Lepidium sativum L.,Nasturtium officinale R. Br., and Rorippa palustris (L.) Besserto white fluorescent light of different photon flux densitiesapplied for different daily durations in a diurnal alternatingtemperature regime of 20 °C/30 °C (16 h/8 h) was quantifiedby linear relations between probit percentage germination andthe logarithm of photon dose, the product of photon flux densityand duration. The low energy reaction, in which increasing dosepromotes germination, was detected in all the seed populationsbut in Barbarea vema and Brassica Juncea the lowest photon doseapplied (10^–5–2 and 10^{–5 7} mol m^–2 d^–1,respectively) was sufficient to saturate the response. Comparisons,where possible, between photoperiods demonstrated reciprocity,i.e. germination was proportional to photon dose irrespectiveof photoperiod, for the low energy reaction in Brassica oleracea(1 min d^–1 to 1 h d^–1), Camelina saliva (1 min d^–1to 8 h d^–1), Eruca saliva (1 min d^–1 to 24 h d^–1),Lepidium sativum (I min d^–1 to 8 h d^–1) and Rorippapalustris (1 min d^–1 to 8 h d^–1), but not in Brassicachinensis and Nasturtium officinale. The high irradiance reaction,in which increasing dose inhibits germination, was detectedin Barbarea vema, Brassica chinensis, Brassica juncea, Brassicaoleracea, and Camelina saliva. The minimum dose at which inhibitionwas detected was lO^–0–3 mol m^–2 d^–1.These results are discussed in the context of devising optimallight regimes for laboratory tests intended to maximize germination The response of germination to photon dose was also quantifiedwith 3 x 10^–4 M GA₂, co-applied (Brassica chinensis, Camelinasaliva, and Lepidium sativum) and with 2 x 10^–2 M potassiumnitrate co-applied (Brassica chinensis). In the latter casepotassium nitrate had no effect in the dark and inhibited germinationin the light, but GA₂, promoted germination substantially inall three species. Variation amongst seeds in the minimum photondose required to stimulate germination was not affected by co-applicationof GA₂, in Brassica chinensis and Camelina saliva, whereas seedsof Lepidium salivum showed a narrower distribution of sensitivitiesto the low energy reaction in the presence of GA₂ Barbarea vema (Mill.) Aschers, Brassica chinensis L., Brassica juncea (L.) Czern. & Coss., Brassica oleracea L. var. gongylodes L., Camelina saliva (L.) Crantz, Eruca saliva Mill., Lepidium satiaum L., Nasturtium officinale R. Br., Rorippa palustris (L.) Besser, Cruciferae, light, gibberellic acid, seed germination, seed dormancy     

甘肃省菊科植物3个分布新记录属

报道了甘肃省菊科植物的3个分布新记录属,母菊属(Matricaria),联毛紫菀属(Symphyotrichum)和艾纳香属(Blumea),以及3个甘肃省分布新记录种,同花母菊[Matricaria matricarioides(Lessing)Porter ex Britton],钻形紫菀[Symphyotrichum subulatum(Michaux)G.L.Nesom]和柔毛艾纳香[Blumea axillaris(Lamarck)Candolle]。     

光温对3种醉鱼草属植物种子萌发的影响

密蒙花、七里香和大序醉鱼草3种醉鱼草的种子细小,千粒重仅12～58 mg,但形态有差异,可以进行种类区分.种子充分吸水后,在20～25℃条件下于5～10 d内就能迅速萌发,15 d时发芽率达到75%以上.光照强度21.6～32.4μmol·m-2·s-1和光照时间12～16 h·d-1均可显著提高七里香种子的发芽率,但光照抑制密蒙花种子萌发,而对大序醉鱼草种子萌发没有明显影响.种子苗移栽后3～5 d,真叶转绿,90%的幼苗可形成健壮植株.     

The Monomolecular and Rectangular Hyperbola as Empirical Models of the Response of Photosynthetic Rate to Photon Flux Density, with Applications to Three Veronica Species

The properties of the rectangular hyperbola and monomolecularfunctions, with respect to the photosynthesis/photon flux density(PFD) relationship, are discussed, and the shortcomings of theformer are highlighted. Both models were fitted to data acquiredfrom three closely related Veronica species of contrasting ecology.The non-linear regression algorithms give estimates, with standarderrors, of light saturated photosynthetic rate, light compensationpoint, dark respiration rate, and photochemical efficiency atlow PFD. While the rectangular hyperbola gave almost as gooda fit to the data as the monomolecular for each species, thelight saturated photosynthetic rate estimate given by the formerwas always unacceptably high in comparison with that indicatedby the obvious trend of the data. Moreover, this tendency wasaccentuated if near-saturating PFDs were removed from data sets,and there was a tendency for the fitting algorithm to becomeunstable. No such problems were encountered with the monomolecularfunction, and it is suggested that this be used whenever a simpleempirical model is required to analyze photosynthesis/PFD data. Veronica montana L, Veronica chamaedrys L, Veronica officinalis L, wood speedwell, Germander speedwell, common speedwell, empirical mathematical model, monomolecular function, rectangular hyperbola function, nonlinear regression, photosynthesis, photon flux density, light saturated photosynthetic rate, light compensation point, photochemical efficiency, dark respiration rate     

Light Penetration and Light-induced Seed Germination in Soil

Light penetration through a Drummer silty clay loam and a Broomfield sand was measured spectrophotometrically and biologically. The spectrophotometric measurements showed that less than 1% of the incident light penetrated 2.2 millimeters at any wavelength between 350 and 780 nanometers for ped sizes up to 1 millimeter. Biological measurements with light-sensitive lettuce (Lactuca sativa) seeds in soil showed that an exposure to light equivalent to about 1 sunny day induced some germination of seeds which were 2 millimeters below the surface, but did not affect seeds 6 millimeters below the surface.     

温度、光照和盐分对外来植物黄顶菊种子萌发的影响

对黄顶菊(Flaveria bidentis)种子的表面形态进行了扫描电镜观察,并从温度、光照、NaCl胁迫及浸种等方面对黄顶菊种子萌发特性进行了探讨.结果表明:黄顶菊种子喜高温,35℃下种子萌发迅速,且发芽率、发芽指数及活力指数最高;光照对种子发芽率影响不大,但随光照时间延长,种子发芽高峰推迟且峰值下降,发芽指数和活力指数逐渐下降;随NaCI浓度升高,种子发芽高峰推迟日.峰值变小,发芽率也呈下降趋势,但低NaCl浓度(0.01 mol/L和0.05 moi/L)胁迫下种子发芽率仍保持在90%以上,且促进了种子发芽指数及活力指数提高及胚根的伸长,结合天津地区黄顶菊生境中土壤的含盐量的分析表明,黄顶菊具有相当强的耐盐性;浸种对种子发芽率和发芽指数影响也很大.因此,黄顶菊成为潜在入侵种与其种子极高的萌发率及耐受高温和盐碱等特性密切相关.     

Response of Soybean Seed Germination to Cadmium and Acid Rain

Cadmium (Cd) pollution and acid rain are the main environmental issues, and they often occur in the same agricultural region. Nevertheless, up to now, little information on the combined pollution of Cd(2+) and acid rain action on crops were presented. Here, we investigated the combined effect of Cd(2+) and acid rain on the seed germination of soybean. The results indicated that the single treatment with the low level of Cd(2+) (0.18, 1.0, 3.0?mg?L(-1)) or acid rain (pH ≥3.0) could not affect the seed germination of soybean, which was resulted in the increased activities of peroxidase and catalase. The single treatment with the high concentration of Cd(2+) (>6?mg?L(-1)) or acid rain at pH?2.5 decreased the activities of peroxidase and catalase, damaged the cell membrane and then decreased the seed germination of soybean. Meanwhile, the same toxic effect was observed in the combined treatment with Cd(2+) and acid rain, and the combined treatment had more toxic effect than the single treatment with Cd(2+) or acid rain. Thus, the combined pollution of Cd(2+) and acid rain had more potential threat to the seed germination of soybean than the single pollution of Cd(2+) or acid rain.     

胡杨种子萌发对温光条件和盐旱胁迫的响应特征

以胡杨(Populus euphratica)种子为材料,分别设置光照(连续光照、12h光照/12h黑暗、连续黑暗)温度(10/15℃、15/20℃、20/25℃、25/30℃、30/35℃和35/40℃)试验、PEG6000渗透胁迫(0、-0.1、-0.2、-0.4、-0.6、-0.8、-1.0、-1.2、-1.4和-1.6MPa)试验和NaCl胁迫(0、0.05、0.10、0.20、0.30、0.40、0.60和0.80mol/L)试验,考察室内种子萌发对温度、光照和盐旱胁迫的敏感性,揭示胡杨种子萌发阶段对生境资源的适应策略。结果显示:(1)胡杨种子在温度(10℃/15℃~35℃/40℃)与连续光照、连续黑暗和12h光照/12h黑暗组合处理条件下均能萌发,且最终种子萌发率均能达到77%以上;3种光照条件下,种子萌发的最适温度范围均为25℃/30℃~30℃/35℃,在该温度范围种子萌发表现出快速、集中的特点,且3种光照条件对种子萌发的影响无显著差异。(2)胡杨种子可以在-1.4~0 MPa渗透势溶液中萌发,而在-1.0~0 MPa间最终萌发率均达到90%以上,且相互之间无显著差异;但当渗透势低于-0.4 MPa时胡杨种子萌发进程和萌发速率受到显著影响,当溶液渗透势低于-1.2 MPa时种子萌发受到显著抑制。(3)胡杨种子可以在0~0.80mol/L NaCl溶液中萌发,而最终萌发率、萌发速率均随着NaCl溶液浓度的增高逐渐降低,但在0~0.20mol/L范围内无显著差异;当NaCl溶液浓度大于0.20mol/L时,种子最终萌发率、种子萌发进程和萌发速率均受到显著抑制,萌发高峰期逐渐向后推移。研究结果表明,胡杨种子萌发时温度比较宽泛,对光照无严格要求,适宜温度下萌发快速集中,且萌发时对盐旱胁迫具有一定程度的忍耐性。这些特性有助于胡杨种子充分利用有限的水分条件而快速完成萌发,是胡杨种子萌发对干旱荒漠地区干旱少雨环境的一种生态适应策略。     

Quantal Response of Fruit and Seed Germination Rate in Quercus robur L. and Castanea sativa Mill, to Constant Temperatures and Photon Dose

A linear relationship between constant temperatures in the sub-optimaltemperature range and germination rate is shown in both Quercusrobur L and Castanea sativa Mill germinated under nominal darkconditions. The mean base temperature was interpolated for Qrobur as 0 8 ? or 2-4 ?, depending on seed lot provenance, andfor C. sativa as 1 -4? The optimum temperature for germinationin Q. robur was about 20? compared with around 28 ? in C. sativaOver the sub-optimal temperature range the distribution of thermaltimes was log-normal for each population studied their spreadvarying both between Q robur seed lots and between species However,in C. sativa germinated close to the mean base temperature,the distribution in thermal times was reduced Thermal timesto germination were decreased in Q. robur and C sativa by approximately0 3 and 0-5 log-units, respectively, when the pericarp was removed,i.e in the seeds, but the sensitivity of the response remainedrelatively unaltered In both species the germination rate was the same when nominaldark or safe green light conditions were employed during thegermination test. However, at 21 ? Q robur exhibited the highirradiance reaction (HIR) at photon doses above 30mmol m^–2d^–1. HIR first affected the germination rate by an inhibitionof radicle extension The sensitivity of the response to thermaltime was reduced as photon dose increased. This photo-inhibitionwas exacerbated at supra-optimal temperatures. In contrast,C. sativa germination rate at 26 ? was little influenced bylight at a photon dose of 752 mmol m^–2 d^–1 Key words: Seed germination rate, temperature, thermal time, light, photon dose     

Effect of Light and Moisture Conditions and Seed Age on Germination of Three Closely Related Myosotis Species

Germination of three closely related species from the Myosotis palustris group (M. nemorosa, M. palustris subsp. laxiflora, M. caespitosa) differing in their habitats and capacity for clonal growth, was compared in two greenhouse experiments. To evaluate both inter- and intraspecific variation, each species was represented by seeds from several populations. Final germination percentage and germination rates T₅₀ were compared both between species and populations within species. In the first experiment, we studied the influence of two external factors, moisture and light. Four moisture levels (dry, wet, periodically flooded and permanently flooded soil) and three types of shading (without shading, shaded with green foil, shaded with solid paper sheet) were combined in a complete factorial design. In all three species, total germination percentage was the same in the three wettest treatments, and decreased in the dry treatment. Germination in the treatments shaded with green foil (simulating vegetation cover, which changed light quality) was significantly slower than in treatments without shading and treatments shaded with a solid paper sheet. There were significant differences among species, but we also found very pronounced differences among populations within a species. M. caespitosa had the uniformly highest germination percentage (reaching in some cases 100%) and also fastest germination. Germination of M. palustris subsp. laxiflora populations was slower and reached lower final proportions, and medium variability among populations. Inter-population variability in the final germination percentage was highest, and the final germination the lowest in M. nemorosa. In addition, M. nemorosa, a species typical for permanent meadow communities was delayed by permanent flooding. In the second experiment, we studied the effects of seed age and storage conditions. Three combinations of seed age and storage were used: younger seeds (half year old) with no-chilling, younger seeds with chilling and old seeds (three years old) with chilling. M. caespitosa had again the highest final germination percentage and fastest germination rates T₅₀. In addition, final germination percentage of this species slightly increased with seed age, whereas it decreased in the other two species. The germination behaviour corresponded well to expectation based on species life histories and habitat preferences. Remarkably stable and high germination percentages and fastest germination rates T₅₀ were ascertained in M. caespitosa, a species of disturbed habitats, with lowest capacity for clonal spread. M. palustris subsp. laxiflora (species with highest clonal capacity) and M. nemorosa (species with medium clonal potential) achieved lower, but still very high final germination percentage. In addition, M. nemorosa showed the highest inter-populations variability in our experiments.     

光信号与激素调控种子休眠和萌发研究进展

休眠是种子植物在长期进化过程中产生的适应性性状, 通过抑制种子在不适宜的环境中萌发进而保证植物能够在逆境中生存。此外, 休眠有助于种子的长距离运输和扩散, 因此休眠对种子延续和物种保存具有重要意义。种子由休眠向萌发的发育转变不仅关系到物种的繁衍, 而且对保证农业生产中作物的产量和品质也具有重要作用。种子的休眠和萌发受到内源激素和外源光信号的共同调控。其中, 外源光信号主要通过调控内源ABA和GA的生物合成及信号转导进而调控种子休眠和萌发。该文系统综述了外源光信号和内源激素调控种子休眠和萌发的作用通路以及两类信号通路之间的交互作用, 旨在为农业生产中利用光和激素调控种子休眠与萌发提供参考。     

光信号与激素调控种子休眠和萌发研究进展

休眠是种子植物在长期进化过程中产生的适应性性状, 通过抑制种子在不适宜的环境中萌发进而保证植物能够在逆境中生存。此外, 休眠有助于种子的长距离运输和扩散, 因此休眠对种子延续和物种保存具有重要意义。种子由休眠向萌发的发育转变不仅关系到物种的繁衍, 而且对保证农业生产中作物的产量和品质也具有重要作用。种子的休眠和萌发受到内源激素和外源光信号的共同调控。其中, 外源光信号主要通过调控内源ABA和GA的生物合成及信号转导进而调控种子休眠和萌发。该文系统综述了外源光信号和内源激素调控种子休眠和萌发的作用通路以及两类信号通路之间的交互作用, 旨在为农业生产中利用光和激素调控种子休眠与萌发提供参考。     

3种锦鸡儿种子萌发对温度和水分的响应

对本地种白毛锦鸡儿（Caragana licentiana）和甘蒙锦鸡儿(Caragana opulens)以及外来种中间锦鸡儿（Caragana intermedia）种子进行了室内和野外萌发试验。结果表明,白毛锦鸡儿种子最适萌发温度为20℃,5℃时种子不萌发,甘蒙锦鸡儿最适萌发温度为10-20℃,在5℃和30℃时萌发率显著低于其它温度下的萌发率,中间锦鸡儿种子最适萌发温度为15-30℃,5℃下的萌发率为8.5%。室内萌发试验和野外萌发试验都表明白毛锦鸡儿种子萌发的速度缓慢,这体现在达到最大萌发率需要的时间长,萌发速度慢,且有4.0%的硬实种子,甘蒙锦鸡儿种子萌发的速度快,无硬实种子,高温下萌发受到一定的抑制。中间锦鸡儿种子在高温下萌发率高,速度快。启运白毛锦鸡儿种子萌发的最低土壤含水量为1.25%,甘蒙锦鸡儿和中间锦鸡儿的分别为3.75%和2.50%。白毛锦鸡儿种子萌发需要的土壤含水量低,种子萌发慢,且有小部分硬实种子,这可能是白毛锦鸡儿适应特殊环境的对策之一。     

三种兜兰属植物种子发育过程及其与无菌萌发的关系

某些兰科植物的种子成熟前,在无菌萌发过程中有较高的萌发率,而成熟后萌发率急剧下降。本研究针对这一现象,对三种兜兰属植物种子的发育过程进行了解剖学观察,并对授粉后不同时期的种子进行无菌播种,80d后统计其萌发率,以探究种子发育过程中的解剖学特征与萌发率之间的关系。研究结果表明种胚刚发育到椭球形胚的时候,胚柄尚存,种皮细胞尚未皱缩,此时三种兜兰的萌发率都能达到较高水平,表明这是适合兜兰属植物萌发的最佳时期;此后,种皮开始皱缩,木质素类物质积累导致种皮透水性下降,推测这可能是导致其后期萌发率下降的主要因素之一。     

Growth Retardants and the Germination of Light Sensitive Lettuce Seed

The effect of the dwarfing compounds chlormequat, B995, and Phosphon D on the germination of lettuce seed in darkness was found to be a depression which could be overcome in part by red light, GA, and kinetin. There was a marked statistical interaction between the growth retardants and all the mitigating treatments except B995 and GA, and light, at 30°C and GA and Phosphon D at 20°C and this implies a biological interaction at the site of action of the growth retardant. It is suggested that the action of the compounds considered is in the establishment of an ordered system since it is unlikely that there would be a common binding site for kinetin and GA.     

Pigment Content of Selected Planktonic Algae in Response to Simulated Natural Light Fluctuations and a Short Photoperiod

The lipophilic photosynthetic pigments in Limnothrix redekei, Planktothrix agardhii (cyanobacteria), Stephanodiscus minutulus, Synedra acus (diatoms), Scenedesmus acuminatus, and Scenedesmus armatus (chlorophycean) all isolated from an eutrophic lake were quantitatively determined by HPLC. The algae were grown semi-continuously under nutrient sufficient conditions at 20°C at a 12/12 h light/dark cycle with constant irradiance or with simulated natural light fluctuations as well as at a 6/18 h light/dark cycle with constant irradiance, all at the same daily light exposure. The zeaxanthin and the myxoxanthophyll contents of cyanobacteria were not influenced by fluctuating light, a short photoperiod or a different sampling time. The chlorophyll b/a ratio, the lutein/chlorophyll a ratio, and the neoxanthin content of chlorophycean as well as the chlorophyll c/a and the fucoxanthin/chlorophyll a ratio of diatoms were only slightly influenced by these factors. Therefore in some cases marker pigment contents and in other cases marker pigment/chlorophyll a ratios may be more useful for quantifying the relative importance of different taxonomic groups in natural phytoplankton. Simulated natural light fluctuations or the length of the photoperiod only slightly influenced the pigment content or the marker pigment/chlorophyll a ratio.     

Lipid Accumulation during Canola Seed Germination in Response to Cinnamic Acid Derivatives

The objective of this research was to investigate how ferulic and p-coumaric acids affect lipid and fatty acid composition during canola (Brassica napus L.) seed germination. Data showed that both compounds increased total lipid and fatty acid contents in the cotyledons during germination. The largest accumulation in lipids occurred at 1.0 mM p-coumaric acid with an increase in all unsaturated fatty acids. The results suggest that allelochemicals interfere in canola seed germination by reducing lipid mobilization.     

光照和温度对大百合种子萌发的影响

研究了不同光照和温度条件对大百合种子萌发的影响。结果表明:光照对大百合种子的萌发有明显促进作用,可提高种子萌发率。种子萌发率以24 h光照20℃恒温最佳。避光条件下温度对大百合种子萌发有影响,其种子萌发最适温度为20℃,11 d开始萌动,3周左右萌发完全,随着温度的升高或降低其种子萌发率下降。萌发前经不同预处理的大百合种子的萌发率不同。同一果实内中部种子萌发最好,上部种子次之,下部种子最差,上、中、下三部分种子萌发率与其千粒重呈正相关。