狭叶柴胡种子萌发与内源抑制物质

分别测定了柴胡种子的水浸提液、水浸泡液与乙醚浸提液对柴胡种子萌发以及对白菜和小麦种子萌发和幼苗生长的抑制活性;用水、乙醚、乙醇和丙酮浸泡柴胡种子,比较其对种子中抑制物质的去除效果;运用原位实验方法探讨柴胡种子萌发与内源抑制物质之间的关系。结果表明：柴胡种子中含有一定活性的内源抑制物质,其对白菜幼根生长的抑制活性高于对白菜种子萌发的抑制活性,对小麦叶绿素含量、鲜质量和α-淀粉酶的活性高于对小麦种子萌发的抑制活性,并且对柴胡自身种子萌发也有明显的抑制作用;室温用乙醚浸种24 h可以提高种子发芽率。据此,建立了柴胡种子的催芽技术。     

种子萌发和休眠的调控

种子的萌发和休眠受外界因子和种子本身的特征如种子的结构、植物激素的含量以及种子所携带的遗传信息等的影响。在种子发育后期,种子成熟脱水,处于发育停滞(develop-mental arrest)。在这个阶段,种子可能是休眠(初生休眠)或者是非休眠(图1)。休眠种子不可能被完全适合的萌发条件诱导萌发。通常应用一定的温度范围能够打破干燥种子的     

果翅对梭梭属(Haloxylon)种子萌发行为的调控

种子萌发行为的受控机制是生殖生态学的重要研究内容。通过果翅存留实验研究了在不同贮藏时期果翅对梭梭和白梭梭种子萌发的影响。结果表明：①新成熟的梭梭种子具有高的萌发率（〉90％）。梭梭果翅对秋天新成熟的种子萌发有显著的抑制作用（萌发率〈50％）,使种子处于强迫休眠状态;果翅对种子萌发的抑制作用随着贮藏时间的推移逐渐降低,到翌年春天（4月）这种抑制作用已完全解除,果翅对梭梭种子的抑制主要是化学抑制。果翅对梭梭种子萌发行为的调控作用确保了种子在合适的时间萌发与种群的成功定居,也正是梭梭在荒漠地区广泛分布的主要原因。②新成熟的自梭梭种子萌发率为59．5％,贮藏1个月后达到80％。表明种子存在短时期的生理后熟现象。白梭梭果翅在每一贮藏时期对其种子的萌发都具有显著的抑制作用,翅＋种子（将果翅与种子剥离。一起放人培养皿中）也部分地抑制种子的萌发,因此,果翅对白梭梭种子萌发的抑制既有化学抑制也存在机械抑制。果翅对种子萌发的抑制,限制了白梭梭的分布。     

几种外源激素对杉木种子萌发的影响

应用ＧＡ、６－ＢＡ和ＡＢＡ等三种外源激素对杉木种于萌发的影响进行了研究．结果表明,ＧＡ较明显促进杉木种子的萌发,而６－ＢＡ和ＡＢＡ则显著地抑制了杉木种子的萌发．当三种激素共同存在时,它们在杉木种子萌发中的相互作用表现为：ＧＡ起促进作用（最适浓度为５０－１００ｐｐｍ）．ＡＢＡ起抑制作用,６－ＢＡ（浓度不超过５０ｐｐｍ）则有解除ＡＢＡ的抑制作用．     

龙胆种子萌发与水溶性内源抑制物质

龙胆种子中含有一定活性的内源抑制物质,其对白菜幼根生长的抑制活性高于对白菜种子萌发的抑制活性,对龙胆种子自身萌发也有明显抑制作用;室温浸种可部分去除龙胆种子内源抑制物质;以150 μg·mL-1赤霉素变温浸种处理种子,可提高种子发芽率.据此建立了龙胆种子催芽技术和羧甲基纤维素悬浮液播种技术.     

种子发芽的抑制物质

许多植物的种子都有休眠现象,引起休眠的原因不一。在排除了胚未成熟,种皮机械障碍等因素后,如果给以适当的温、光、气、水条件仍不萌发,则应考虑是否有发芽抑制物的存在。发芽抑制物的种类抑制种子发芽的物质很多,既有简单的无机物,也有许多有机物及植物激素。氢氰酸（HCN）是常见的发芽抑制物,主要以耷的形式分布于植物界中。如苦费科中的梅、杏等,其种子中的苦杏仁耷含量可达百分之几。银杏、甘薯、高粱、亚麻等种子中均含有抑制种子萌发的各种氨氰酸的着类。如果在播有小麦种子的培养血中放两个苦杏仁,小麦种子发芽就受到抑…     

梣叶槭种子中的抑制物质及其与种子萌发的关系(简报)

梣叶槭种子的果皮、种皮(内外)和种仁内均有抑制物质存在,果皮和种仁内较多。低温(5℃,10℃)和变温(30℃昼/5℃夜)层积的种仁内抑制物质显著减少,种子萌发加速。种子完成生理后熟后,果皮和种皮内虽然滞留一些抑制物质,但种子仍然可以萌发。     

榛树种子的休眠和萌发

鉴定榛子各部分浸提液的结果显示 ,果皮、种皮及胚都存在导致休眠的抑制物质 ;榛树果实有一定的吸水性 ,据此推测种子休眠可能不是因果皮的不透水性造成 ;0 .5、2、5mg·L-16 BA可以解除种子休眠 ,促进萌发。     

外源cGMP调控盐胁迫下黑麦草种子萌发机制

c GMP(cyclic guanosine-3',5'-monophosphate)是一类环化核苷酸,能响应植物非生物胁迫的信号分子。以c GMP的膜透性类似物8-Br-cGMP为供体,研究c GMP对盐胁迫下黑麦草种子萌发及生理指标的影响。通过计算萌发指标、测定种子萌发过程中各项生理指标,探讨c GMP对黑麦草种子萌发时耐盐机制的作用。结果表明:低浓度(50 mmol/L)盐胁迫能促进黑麦草种子的萌发,随着盐浓度(100、150、200、250 mmol/L)的增加黑麦草种子的萌发率逐渐降低甚至抑制其萌发。而加入20μmol/L c GMP能缓解100 mmol/L Na Cl胁迫对黑麦草种子造成的伤害,使黑麦草种子的发芽率、发芽势、发芽指数、活力指数分别提高了7.4%、133.3%、52.1%、104.2%。此外,研究发现加入20μmol/Lc GMP能够促进100 mmol/L Na Cl盐胁迫下黑麦草萌发期根的生长,比单独100 mmol/L Na Cl盐胁迫处理下的黑麦草植株全长、根长、叶长分别提高了2.5、2.8倍和2.6倍,种子在萌发过程中可溶性糖、可溶性蛋白含量、淀粉酶活性,脯氨酸含量分别提高了47.9%、15.7%、94.3%、117.4%,而淀粉含量、MDA含量、电导率,O_2~-产生速率分别降低了40.9%、128.7%、88.6%、211.9%。说明20μmol/Lc GMP通过提高可溶性糖,可溶性蛋白含量及脯氨酸含量,同时减少MDA、O_2~-的产生,以此缓解盐胁迫对黑麦草种子的伤害、同时促进淀粉水解,从而加速种子萌发。     

Ethylene in seed dormancy and germination

The role of ethylene in the release of primary and secondary dormancy and the germination of non-dormant seeds under normal and stressed conditions is considered. In many species, exogenous ethylene, or ethephon – an ethylene-releasing compound - stimulates seed germination that may be inhibited because of embryo or coat dormancy, adverse environmental conditions or inhibitors (e.g. abscisic acid, jasmonate). Ethylene can either act alone, or synergistically or additively with other factors. The immediate precursor of ethylene biosynthesis, 1-aminocyclopropane-1-carboxylic acid (ACC), may also improve seed germination, but usually less effectively. Dormant or non-dormant inhibited seeds have a lower ethylene production ability, and ACC and ACC oxidase activity than non-dormant, uninhibited seeds. Aminoethoxyvinyl-glycine (AVG) partially or markedly inhibits ethylene biosynthesis in dormant or non-dormant seeds, but does not affect seed germination. Ethylene binding is required in seeds of many species for dormancy release or germination under optimal or adverse conditions. There are examples where induction of seed germination by some stimulators requires ethylene action. However, the mechanism of ethylene action is almost unknown.
The evidence presented here shows that ethylene performs a relatively vital role in dormancy release and seed germination of most plant species studied.     

Rna synthesis during the germination of wheat seed

Incorporation of [¹⁴C]uridine into various RNA fractions of germinating wheat embryo was studied. During the first 3 hr of germination the precursor was incorporated predominantly into a specific component of the RNA (messenger RNA). Neither ribosomal nor transfer RNA were labeled at this time. It is concluded that biosynthetic processes are resumed after the breaking of dormancy in a sequential manner. This sequence begins with the initiation of messenger RNA synthesis.     

Seed biology and in vitro seed germination of Cypripedium

Abstract

Cypripedium orchids have high horticultural value. The populations of most species are very geographically restricted and they are becoming increasingly rare due to the destruction of native habitats and illegal collection. Reduction of the commercial value through large-scale propagation in vitro is a preferable option to reduce pressure from illegal collection. Cypripedium species are commercially propagated via seed germination in vitro. This review focuses on in vitro seed germination and provides an in-depth analysis of the seed biology of this genus.     

Effect of lanthanum on aged seed germination of rice

Attempts were made to promote germination of natural aged rice seeds by treating them with lanthanum nitrate. In tests to measure the germination rate, germination index, and vigor index of natural aged rice seeds were found to be significantly increased by lanthanum. It is treating aged rice seed with lanthanum nitrate that enhanced the respiratory rate and activities of superoxide dismutase, catalase, and peroxidase, and decreased superoxide and malondidehyde contents, and therefore reduced plasma membrane permeability. It suggests that lanthanum may be used to pretreat seed before sowing.     

箭根薯种子的贮藏与萌发

就温度、光照和土壤水分对箭根薯 (TaccachantrieriAndre )种子萌发的影响及种子贮藏条件进行了研究 ,结果表明 ,箭根薯种子是需光性种子 ,萌发温度较窄且要求有较充分的土壤水分 ,其萌发的最适宜温度为 2 5～ 30℃ ,最适宜土壤水分为 6 0 %～ 70 %;室温干燥贮藏比室温常规贮藏效果好 ,而高温高湿和低温高湿都导致其发芽率迅速下降。箭根薯种子耐脱水、耐低温和耐贮藏 ,可以用种子库常规的种子保存技术实现长期保存。研究认为 ,目前箭根薯的濒危状态既有物种自身的原因也有生境破坏的原因 ,该物种宜采取就地保护、迁地保护和种子保存相结合的方法进行种质资源保存。     

Mathematical description of the seed germination dependency on time and temperature

Abstract. A mathematical model which describes the germination percentage dependency on time and temperature of a seed population was derived from the experimental results with a seed population of Amaranthus patulus Bertol. under sub-optimal temperature conditions (Washitani & Takenaka, 1984). The equation of the model which is a modified thermal time model is where G is germination percentage at a certain time after the start of imbibition ( t ) at a certain temperature ( T ), μ _{T 1} and σ _{T 1} are the mean and standard deviation of lower limit temperature among the seeds belonging to the seed population, and Tb, m , and A are the parameters characterizing the linear relationship between the rate and temperature, namely, Tb is the base temperature, m , the median of the required thermal time and A , a parameter determining the pattern of the variation of the required thermal time within seed population, respectively. The equation yields time courses for germination which are very similar to those observed by experiment.     

云锦杜鹃种子萌发及对干旱胁迫的响应

以不同渗透势的PEG-6000溶液模拟干旱胁迫条件, 研究云锦杜鹃种子的萌发、幼苗生长和累积吸水率对干旱胁迫的响应。结果显示：种子于第14 d开始萌发,萌发期为8 d,总萌发率为45.5%±1.7%。在渗透势为-0.3～-0.6 MPa的溶液中, 种子的累计吸水率在第5 d就超过对照(蒸馏水中), 种子的萌发和幼苗的生长也优于对照, 说明云锦杜鹃种子不适合过于湿润的土壤环境中萌发。但溶液的渗透势≥-0.9 MPa时, 种子的吸水减缓、萌发率下降, 同时幼苗的生长也慢, 而当渗透势≥-1.8 MPa时, 种子不能充分吸涨、萌发, 说明云锦杜鹃种子对干旱胁迫比较敏感。另外, 经PEG溶液浸种2天后移入蒸馏水中,萌发率均有一定程度的提高, 其中经-0.3～-1.5 MPa的PEG溶液浸种后, 萌发率显著高于对照。提示用一定浓度范围的PEG溶液浸种可使休眠种子活化, 提高种子繁育的效率。