温水浸种对蒙古黄芪种子萌发特性的影响

研究温水浸种破除蒙古黄芪（Astragalus membranaceus Bge.var.mongholicus（Bge.） Hsiao）种子休眠的适宜条件,采用恒温和变温2种浸种方式,测定蒙古黄芪种子在不同时间、不同温度梯度条件下的发芽率、发芽势和发芽指数。结果表明,温水浸种破除蒙古黄芪种子休眠的效果显著,变温浸种效果略优于恒温浸种。不同温度破除休眠效果排序依次为60℃> 70℃> 80℃,其中60℃变温浸种2 min和5 min的发芽率分别为对照的2.87倍和2.31倍。浸种时间、浸种温度均可显著影响蒙古黄芪种子萌发,与对照相比,随着浸种时间增加,发芽率总体呈现出先急速升高后逐渐降低的趋势;发芽指数与浸种温度极显著正相关;浸种温度与发芽势和发芽指数均显著正相关。本研究结果表明温水浸种可以提高种子发芽率,保持种子活力。     

假酸浆种子发芽特性研究

在不同温度、不同贮藏时间和方法下,对来源于印度尼西亚的假酸浆种子发芽特性进行研究。结果表明:不同温度对假酸浆种子萌发的影响差异极显著,在15/25℃变温条件下种子发芽率最高,为84.3%,发芽快且整齐;假酸浆种子采收后立即播种其发芽率非常低,室温下贮藏6～9个月时在25℃恒温或15/25℃变温条件下均有较高发芽率,说明假酸浆种子有休眠性,通过延长贮藏时间能打破休眠,促进种子发芽;但室温贮藏15个月后,种子活力下降非常明显。低温冷藏在一定条件下能提高假酸浆种子萌发能力,能延长种子寿命。     

外源激素与温度对花楸树种子萌发的影响

三种外源激素和萌发温度对花楸树种子萌发影响的研究结果表明,25℃（16h光／8h暗,10d）-5℃（暗110d）变温可极显著提高种子发芽率和种子发芽势,但极显著延迟发芽初始时间。200mg·L^-16-BA溶液中吸胀2d后经历25℃·5℃变温可使种子发芽初始时间最短（33d）,发芽率（62．25％）和发芽势（57．88％）最高。GA3或ABA与温度的结合处理对种子萌发的促进作用小于6-BA与温度的综合处理。     

温度和水分及盐分胁迫对银沙槐种子萌发的影响

利用控制实验研究了温度、湿度、干旱和盐分胁迫等生态因子对银沙槐种子萌发的影响,以探索银沙槐种子对各种生态因子的适应性。结果显示:(1)银沙槐种子在20℃、25℃恒温和15℃/25℃、20℃/30℃、10℃/20℃变温环境中的发芽率较高且无显著差异,其在20℃恒温、15℃/25℃、20℃/30℃变温条件下的发芽指数较高,但差异不显著。(2)土壤含水量在1%～5%之间,各水分处理间种子发芽率差异显著(P<0.05),而在5%～25%间种子发芽率变化不显著。(3)盐胁迫和水分胁迫对银沙槐种子的萌发均有明显的抑制作用,可显著降低种子萌发率(P<0.05);种子发芽指数和活力指数均随渗透势和NaCl浓度增大而显著减小(P<0.05);恢复萌发率随渗透势和NaCl浓度的增加而显著增加(P<0.05)。研究发现,银沙槐种子萌发最适温度为20℃恒温和15℃/25℃变温,最适土壤含水量为10%～25%;种子萌发对盐分和干旱胁迫表现出不同程度的耐受性,萌发过程中主导抑制因素为渗透胁迫,离子毒害作用甚微;银沙槐种子休眠机制和萌发特征表现出它对生境的良好适应性。     

光照和不同药剂浸种对龙葵种子发芽率的影响

为探索超富集植物龙葵种子的快速发芽方法,以滤纸为发芽基质,采用恒温培养箱及温室培养的方法,对龙葵种子进行不同浸种处理,探讨光照及不同浸种液对龙葵种子发芽的影响.结果表明: 光照条件是龙葵种子发芽的重要条件之一,光照条件下的发芽率约为无光照条件下发芽率的5倍(P<0.05);不同浸种液均能显著提高龙葵种子的发芽率,其中以双氧水的处理效果最好,发芽时间最短(P<0.05);浸种后不经清洗处理的龙葵种子发芽率约为浸种后再经清洗处理发芽率的2～3倍(P<0.05).     

桔梗种子萌发对低温、干旱及互作胁迫的响应

以药用植物桔梗种子为材料,研究了低温、干旱及其互作对种子萌发和幼苗生长的影响,旨在探索在春寒干旱条件下其种子萌发对策及生态适应性,为桔梗野生种群恢复及人工栽培群体构建提供依据.结果表明,温度、干旱及其互作对桔梗种子萌发和幼苗生长均有显著影响.0-10％ PEG水分条件下,在变温10/20℃及恒温15-25℃下桔梗种子能够良好萌发(10％ PEG、20℃除外),而15％ PEG可显著抑制萌发.低温(10℃)下种子萌发始时间延迟,发芽率降低.随干旱胁迫程度的增加,10℃发芽率呈先升后降趋势,而其它温度下,发芽率和发芽指数均呈下降趋势.随温度的降低,幼苗根长、茎长及鲜重均呈下降趋势,且幼根生长对温度变化更为敏感.     

外源赤霉素GA3对混合盐碱胁迫下小白菜种子萌发的影响

以小白菜（Brassica campestris ssp．chinensis L．）为材料,通过采用不同浓度的外源赤霉素（GA3）浸种处理,研究了GA3对混合盐碱胁迫下小白菜种子的发芽率（Gr）、发芽势（Gv）、发芽指数（Gi）以及根毛区宽度和胚长的影响。结果表明：混合盐碱胁迫下,小白菜各发芽指标均显著低于对照,GA,处理后,各指标均显著提高,且随外源GA3浓度的增加,各指标均表现出先增后减的趋势,当GA3浓度达80mg／L时,各发芽指标达到峰值,说明80mg／LGA3可使混合盐胁迫下小白菜种子萌发的缓解作用达到最佳。同时外源GA3处理还可不同程度地缓解盐胁迫对小白菜种子a-淀粉酶活性的抑制。     

小蓬种子萌发特性和幼苗分布格局研究

对小蓬(Nanophyton erinaceum)种子萌发特性和小蓬幼苗分布格局进行了调查研究。结果表明,小蓬在20℃条件下的发芽效果最好;小蓬种子的发芽不需要光照,但是全光照情况下发芽速度比在黑暗条件下快;在变温条件下,小蓬种子的发芽率有所提高,其中以15℃和10℃变温条件下的发芽效果最佳;不同坡向种群种子发芽率和千粒重存在明显差异,表明不同种群种子是异质的;通过调查发现小蓬主要在靠近母株一定范围内依靠种子进行自然更新。     

林线树种太白红杉种子萌发的生理生态特性

 太白红杉(Larix chinensis)是太白山的高山林线树种。通过在人工气候室内的试验,研究了太白红杉种子在6种不同的光照与温度组合处理条件下的萌发特性。结果表明：在恒温和变温两种条件下,交替光照对于种子吸胀后的脱落酸（ABA）和赤霉素 (GA)有刺激作用。在恒温条件下,持续光照对于种子吸胀后的生长素 (IAA)有刺激作用,而变温条件下交替光照对生长素有刺激作用。细胞分裂素（CTK）的变化情况与IAA相反。光照条件相同时,恒温条件下的植物激素含量要高于变温条件下的含量,说明恒温对于各种激素有刺激作用。在25 ℃环境下种子的萌发率高于在12 ℃环境下的萌发率,说明温度对于种子的萌发有重要作用。太白红杉种子的萌发受交替光照（12 h光照/12 h黑暗）的刺激;恒温（25 ℃）条件下的种子萌发率高于变温（12 ℃/25 ℃）条件下的种子萌发率。实验结果反映了内源激素在太白红杉种子萌发过程中起着重要作用。     

濒危植物秦岭冷杉种子萌发特性的研究

 秦岭冷杉(Abies chensiensis)为中国特有种,主要分布于中国秦巴山地,现为渐危种,被列为国家二级保护植物。经测定,秦岭冷杉种子千粒重为(33.92±1.01)g,与其它冷杉属的种子比较,其种子千粒重较大。四唑（TTC,1.0 %）染色测种子生活力的结果表明:有生活力的种子占26.00%,空粒占20.50%,涩粒占33.75%,说明秦岭冷杉种子饱满度很差,反映了比较高的种子败育率;染色结果与对比发芽实验的结果很接近,说明用四唑染色来测定秦岭冷杉种子的生活力是较准确的方法。把种子进行0、14、21、28d低温(4℃)层积处理,发现低温层积可以显著提高种子发芽率和发芽势,但是层积21d与28d发芽势没有差异。设置恒温20℃、25℃和变温20～30℃ 3种温度条件下发芽比较,发现最终的发芽率并没有差异,但是发芽势差异显著,恒温25℃达到最大发芽率的90%的时间要比另外两种温度下提前9d,可见25℃是秦岭冷杉种子发芽的适宜温度。光照(8 h·d-1,100μmol·m-2·s-1)和黑暗下种子的最后发芽率差异不显著,但是光照发芽势高,可见光照可以促进秦岭冷杉种子发芽迅速、整齐。实验证明,用砂床做发芽基质与用纸床做发芽基质相比,前者的发芽率和发芽势均比后者高。     

The effect of the embryo axis and exogenous sucrose on lipolysis and glyoxysomal enzyme development in Ricinus communis (castor bean) endosperm and cotyledons

Post-germinative growth in castor bean ( Ricinus communis L. cv. Hale) seedlings was investigated to determine whether lipolytic enzyme synthesis and lipid breakdown was a function of the embryo axis or simply based on a source-sink mechanism connected with sucrose produced during mobilization of storage lipid. Endosperm and cotyledons were excised from the embryo axis at 24 h intervals and were then incubated in Petri dishes containing water or 0.1 M sucrose for 24 h. Excised endosperm showed similar or higher malate synthase (MS, EC 4.1.3.2) and isocitrate lyase (ICL, EC 4.1.3.1) activities and increased lipolysis when compared with endosperm obtained from similarly intact seedlings of the same age. In contrast, cotyledonary ICL and MS activity was up to 50% lower and lipolysis was only slightly affected in excised material when compared with cotyledons obtained from intact seedlings. Incubating endosperm in sucrose had no effect on the development of the above enzyme activities or lipid content, when compared with material incubated in water only. In contrast, cotyledonary MS and ICL activities were up to 70% lower in sucrose and lipolysis substantially inhibited. Lipid breakdown and the development of lipolytic enzyme activity in cotyledons seem to be dependent on the presence of the endosperm. It is concluded that enzyme regulation in castor bean seedlings cannot entirely be explained by axis control or source-sink relationships.     

香圆种子萌发特征及催芽技术

以香圆（Citrus wilsonii Tanaka）种子为实验材料,通过测定种皮透水性、种皮机械障碍、发芽温度等对种子萌发的影响从而探讨种子萌发特征;通过切割种子、热水浸种、赤霉素浸种、低温层积等处理方式探索种子的催芽方法。结果显示：香圆种皮不存在透水性障碍,但其机械障碍对种子萌发具有抑制作用,且内种皮对萌发影响较大;种子在15℃、25℃、35℃恒温及15℃/30℃变温条件下均可萌发,其最适萌发温度为25℃;采用低温层积、热水浸种、切除1/3种子等方法均可一定程度上促进种子萌发。生产中宜采用始温60℃热水浸种24h的方法对香圆种子进行催芽。     

Coelomomyces psorophorae vartasmaniensis Couch+Laird (1988) (Coelomomycetaeceae: Blastocladiales), a fungal pathogen of the mosquitoAedes australis

The germination of sporangia inCoelomomyces psorophorae vartasmaniensis (C. p. tas.) is uncoordinated and thus there is a mixture of developmental stages in any given population. Continuous urografin gradients separated out the critical stages of germinating sporangia giving four bands, each band representing a consecutive stage of germination. These stages were investigated for changes in the sporangial wall using Transmission Electron Microscopy (TEM). The sporangia have a typical two-layered wall, an electron dense outer layer which can be divided into three distinct sub-layers D1, D2, and D3 and an inner electron transparent secondary wall. Stage 3 sporangia have an intact D1 layer on their outer wall. In the subsequent stages (4 & 4b) there is a progressive breakdown of this layer.     

The physiological basis of seed dormancy in Avena fatua III. Action of nitrogenous compounds

Sodium nitrate and nitrite (50–100 m M ) induced germination in three out of four genetically pure dormant lines of Avena fatua L. The sensitivity to these treatments was low immediately ater harvest and increased markedly after six months of dry after-ripening. The observation that a fourth dormant line failed to respond suggests at least two metabolic blocks may be involved in expression of dormancy. An inhibitor of gibberellin biosynthesis, 2-chloroethyl trimethylammonium chloride, completely inhibited the dormancy-breaking effect by nitrate and nitrite, indicating a requirement for gibberellin biosynthesis. Among reduced nitrogenous compounds, ammonium chloride and urea failed to break dormancy in all partly after-ripened lines, suggesting that nitrate and nitrite may induce germination through their ability to act as electron acceptors. The sensitivity to all nitrogenous compounds tested increased with the length of after-ripening indicating that the depth of the second dormancy block amy decrease with the time of after-ripening. Other reduced nitrogenous compounds, thiourea and hydroxylamine hydrochloride, promoted some germination in the least dormant, partially after-ripened lines. The function of these compounds as electron acceptors and their similarity in activity to the cytochrome oxidase inhibitor, sodium azide, is discussed with reference to dormancy and the possible involvement of the alternative pathway of respiration.     

Indirect effect of abscisic acid on the induction of secondary dormancy in lettuce seeds

During temporary incubation at 25°C in buffered solutions (pH 4.0) of abscisic acid (ABA) seeds of lettuce ( Lactuca sativa L. cv. Olof) lost the red-light initiated ability to germinate in buffer. The development of secondary dormancy required an inhibitory ABA content in the seeds during a number of days. A temporary incubation in ABA during 24 h met these requirements only if the solution was about 100-fold more concentrated than during continuous incubation. Studies with 2-¹⁴C-ABA showed that the amount of ABA which had penetrated in 24 h was reduced by a factor 100 within 3 to 4 days during subsequent incubation in buffer. Both leaching and metabolic changes were involved in the reduction process. The nature of the metabolic products remained obscure. A shift to 2°C after incubation in ABA prevented the induction of secondary dormancy, but inhibited ABA metabolism. ABA did not interfere with the induction rate of secondary dormancy, and it was not required to maintain the state of dormancy. The sole function of ABA was the non-specific inhibition of germination, which indirectly facilitated the development of an ABA independent secondary dormancy. – The level of endogenous ABA was compared to the amount of ABA found in the embryo during and after incubation in ABA solutions marked with 2-¹⁴C-ABA. The level of endogenous ABA in air-dry seeds (0.11 ng/mg dry weight) corresponded to the minimal level at which penetrated ABA inhibited germination. This level had to be present at least during 4 to 5 days to inhibit the effect of red light. Since endogenous ABA was quickly reduced upon imbibition, a regulatory function of endogenous ABA in the inhibition of red light induced germination can be ruled out. A function in the temporary inhibition of dark germination and, consequently, in the development of secondary light irresponsiveness cannot be excluded, however.     

Testing the potential seed availability in dung samples: comparison of two seedling emergence methods

To optimize the estimation of species composition and viable seed content of herbivore faeces and to make different approaches comparable, two seedling emergence methods are evaluated. The Ter Heerdt method (TH) employs concentrated samples, potentially increasing and accelerating seedling emergence, as shown for soil samples (95% of all seedlings emerged within 6 weeks). Samples are kept under controlled conditions (glasshouse or climate room). Secondly, a common garden method (CG) using unconcentrated samples so that seasonal changes could fulfill the germination requirements of a broad species spectrum (experiment duration approximately 15 months) was applied. The methods were tested by the use of sheep faeces samples, collected during a six-day grazing period in a threatened dry grassland (Allio-Stipetum capillatae).Both methods proved largely similar in species composition (QS=0.81) and viable seed content (QS=0.69). More species (e.g. monocotyls) and a higher seedling emergence of hard-seeded species (Fabaceae and Cistaceae) were found in the CG method. Besides a higher emergence of some small-seeded winter annuals, few other species emerged exclusively by use of the TH method. Nevertheless, all species detected by only one method were found in low individual numbers (4).Depending on research interest and availability of space and time, the most appropriate method can be chosen. If the main focus is on the species composition, unconcentrated faeces samples can be studied by CG. In case the overall viable seed content is more important and/or a shorter time period is available, TH serves as a suitable alternative.     

Effects of salt,alkali and salt–alkali mixed stresses on seed germination of the halophyte Salsola ferganica (Chenopodiaceae)

Salsola ferganica L. (Chenopodianceae) is an annual halophytic species. Experiments were carried out in laboratory to determine the effects of temperature, perianths and various types of salinity on seed germination and germination recovery. Seeds were germinated at 6 levels of temperature with perianths, plus perianths and removed perianths in complete darkness for 9 days. The germination responses of the seeds without perianths at 25 °C were determined over a wide range of NaCl, NaHCO₃ or NaCl–NaHCO₃ mixed stress for 13 days. Perianths seriously affected germination as a barrier for seed germination and the optimal temperature was at 25 °C. Highest germination percentage was obtained under control and seed germination was progressively inhibited with the increase of salinity concentration. The negative effect of NaHCO₃ at the same concentration on germination was stronger than that of NaCl and NaCl–NaHCO₃ mixed. When substrate salinity was removed, seeds exposed to a high NaCl concentration (400–800 mM), NaHCO₃ (50–200 mM) and NaCl–NaHCO₃ mixed (100–400 mM) germinated well. Final germination of Salsola ferganica seeds was significantly affected by types of salt at the low salinity (?200 mM) and with increased salinity it was influenced mainly by salinity concentration for various proportion of salt–alkali mixed stress.     

The scutellum of Avena: a structure to maximize exploitation of endosperm reserves

NEGBI, M. & SARGENT, J. A., 1986. The scutellum of Avena : a structure to maximize exploitation of endosperm reserves . The scutella of graminaceous embryos possesses a well developed vascular system and a surface epithelium of closely packed cells. The epithelial cells typically elongate during germination and separate to form papillae, thereby increasing the interfacial area for exchange between the endosperm and embryo. Avena and a dozen non-crop genera are distinguishable by a scutellum which grows into and through the endosperm. Thus diffusion pathways for mobilized reserves in Avena are kept short. The course of elongation of the scutellum and of its epithelial cells in A. Jatua was studied during germination and seedling establishment. A comparison was made with with the fully developed scutellum of Secale cereale which does not elongate but only forms papillae. It is proposed that the competitive success of A.Jatua as a weed is attributable in part to an ability, conferred by its scutellum, to exploit its seed reserves steadily and fully during germination and seedling development.     

Germination ecology of three endangered river corridor plants in relation to their preferred occurrence

As a contribution to conservation, we investigated germination requirements of three perennial, endangered river corridor plants of Central European lowlands coexisting in subcontinental flood meadows, but preferring particular zones of decreasing flooding frequency and duration along the elevational gradient of the banks. It was hypothesized that the species have specific germination requirements to respond successfully to open patch creation depending on their occurrence along the gradient of spring flooding in the field. This study involved controlled experiments and phenological studies.     

Proteomic analysis of rice (Oryza sativa) seeds during germination

Although seed germination is a major subject in plant physiological research, there is still a long way to go to elucidate the mechanism of seed germination. Recently, functional genomic strategies have been applied to study the germination of plant seeds. Here, we conducted a proteomic analysis of seed germination in rice (Oryza sativa indica cv. 9311) - a model monocot. Comparison of 2-DE maps showed that there were 148 proteins displayed differently in the germination process of rice seeds. Among the changed proteins, 63 were down-regulated, 69 were up-regulated (including 20 induced proteins). The down-regulated proteins were mainly storage proteins, such as globulin and glutelin, and proteins associated with seed maturation, such as "early embryogenesis protein" and "late embryogenesis abundant protein", and proteins related to desiccation, such as "abscisic acid-induced protein" and "cold-regulated protein". The degradation of storage proteins mainly happened at the late stage of germination phase II (48 h imbibition), while that of seed maturation and desiccation associated proteins occurred at the early stage of phase II (24 h imbibition). In addition to alpha-amylase, the up-regulated proteins were mainly those involved in glycolysis such as UDP-glucose dehydrogenase, fructokinase, phosphoglucomutase, and pyruvate decarboxylase. The results reflected the possible biochemical and physiological processes of germination of rice seeds.