The Possible Role of Low Temperature in Breaking the Dormancy of Seeds of Fraxinus excelsior L.

It has been shown that the growth-inhibiting substances presentin the embryo and endosperm of F. excelsior are not removedduring pretreatment or during the actual germination process.On the other hand, evidence is presented that the inhibitormay be physiologically effective in preventing germination.A biological assay technique using embryos of the same speciesfrom which the growth substances were extracted was used todemonstrate the production of a germination and growth-promotingsubstance during the process of low temperature after-ripeningand its apparent counteraction of the effect of the endogenousinhibitor.     

硬实种子休眠的机制和解除方法

硬实是植物中普遍存在的现象。硬实种子种皮透水透气性差和对胚生长的机械限制, 引起种子休眠。遗传因素、母株环境、贮藏条件、采收方法、种子本身的成熟度、含水量、大小、形状及颜色都能影响种子硬实率。硬实的处理方法大体可分物理、化学和生物3类, 这些方法通过改善种皮的通透性,促进气体交换和水分进入, 消除机械限制而促进萌发。物理方法有机械损伤、低温和高温处理、干湿交错处理、辐射和高压处理等; 化学方法有酸蚀、碱液浸泡和有机溶剂等处理。硬实休眠有利于植物调节种子萌发的时空分布, 在种质保存上也具有特别重要的意义。     

硬实种子休眠的机制和解除方法

硬实是植物中普遍存在的现象。硬实种子种皮透水透气性差和对胚生长的机械限制,引起种子休眠。遗传因素、母株环境、贮藏条件、采收方法、种子本身的成熟度、含水量、大小、形状及颜色都能影响种子硬实率。硬实的处理方法大体可分物理、化学和生物3类,这些方法通过改善种皮的通透性,促进气体交换和水分进入,消除机械限制而促进萌发。物理方法有机械损伤、低温和高温处理、干湿交错处理、辐射和高压处理等;化学方法有酸蚀、碱液浸泡和有机溶剂等处理。硬实休眠有利于植物调节种子萌发的时空分布,在种质保存上也具有特别重要的意义。     

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。     

Dormancy in Light-sensitive Lettuce Seeds

Relatively brief treatment of imbibed seeds of positively photoblasticlettuce (Lactuca sativa L. cv. Cannington Forcing) with lowconcentrations of ethanol promotes germination. It is suggestedthat this effect is upon a cellular membrane, a view which issupported by the fact that a subsequent treatment with Ca²⁺markedly reduces the ethanol promotion. Data from experiments involving movement and transfer of seedsprovide no support for the involvement of a stable, leachable,endogenous inhibitor in the control of germination. It is concludedthat whether or not the seeds break dormancy is determined bythe interplay between forces generated in the developing embryoand the mechanical restraint provided by the tissues which envelopit.     

蔷薇种子的休眠及解除方法

分析了蔷薇(Rosa L.)种子休眠原因、解除休眠方法以及环境条件对休眠与萌发的影响.蔷薇种子休眠的主要原因有瘦果果皮和种皮的限制作用,胚生理休眠以及果肉、瘦果果皮、种皮和胚中的抑制物质.解除休眠的方法包括去除瘦果果皮限制、解除胚的生理休眠、去除抑制物质等.种子发育过程中及成熟后,环境因子,如温度、水分和光照,对种子休眠和萌发有影响.此外,微生物、果实采集时间也对种子休眠及萌发有较大影响.蔷薇种子的休眠机制复杂,且种间差异很大.     

Positional‐Species Composition of Diacylglycerol Acetates from Mature Euonymus Seeds

The positional‐species composition (PSC) of 3‐acetyl‐1,2‐diacyl‐sn‐glycerols (AcDAGs) from the seeds of mature fruits of 14 species of the genus Euonymus L. was established. The residues of six major fatty acids (FAs), palmitic ( P ), stearic ( St ), hexadecenoic ( H ), octadecenoic ( O ), linoleic ( L ), and linolenic ( Ln ), were present in the AcDAGs. Here, we demonstrated that the profile of PSC of AcDAGs could serve as chemotaxonomic factor to divide euonymus species studied here into groups which completely correlate with the present day systematic of the genus. In particular, the Euonymus section greatly exceeded other sections of the Euonymus subgenus as well as the Kalonymus one in the total levels of AcDAGs positional species having one and two O residues and was characterized by significantly lesser concentrations of species with one and two L residues. Moreover, in seed, AcDAGs of almost all Euonymus species EF_L values were slightly higher than EF_O ones, but all EF_L and EF_O values were higher than 1.0, and therefore, it can be concluded that both FAs mainly esterified sn‐2‐position of the glycerol moiety and saturated FAs residues were always virtually absent in the sn‐2 position of Euonymus seed AcDAGs, as it is also the case in nearly all TAGs molecules of plant origin.     

Dormancy Mechanism and the Effect of Scarification in the Germination of Halimium halimifolium Seeds

Germination of Halimium halimifolium seeds was very low during the experimental period. The scarification treatment enhanced the germination significantly at all the three temperatures tested, indicating that H. halimifolium seeds are endowed with complex dormancy mechanisms. The highest temperature (30°C) showed an adverse effect which can be correlated with a secondary dormancy at embryo level.The lipidic nature of H. halimifolium exotesta is probably the first factor causing dormancy in this species, acting both as a water and oxygen barrier. We can conclude that H halimifolium shows a tegumentary dormancy, which is presumably located at exotesta level.     

Embryo Dormancy in Seeds of Acer platanoides

On dispersal the seed of Acer platanoides contained a dormant embryo, from which dormancy could be removed by chilling but not by hormone application. Dormany was deep in the embryonic axis, particularly in the radicle, but less so in the cotyledons. Under the storage conditions employed the dormancy pattern was modified so that during the subsequent incubation at 20°C, cotyledon expansion of isolated embryos from stored fruits was more rapid than that of isolated embryos from newly dispersed fruits. In addition, the dormancy of isolated embryos from fruits stored for several weeks could be broken by incubation in kinetin. It was concluded that embryo dormany in this seed can be divided into two phases, an initial phase when the embryo responds to chilling but not to cytokinins, and a later phase when cytokinins also become effective. The relationship between this transition and the apparent gradual reduction in the depth of embryo dormancy during storage is also discussed. The chilling period necessary for dormancy breaking was reduced by kinetin and to a lesser extent by gibberellin, indicating a close relationship between the concentrations of these hormones and the chilling requirement.     

Dormancy in Seeds of Anona crassiflora Mart

The seeds of Anona crassiflora Mart., an important tree of theBrazilian cerrado, have been found to take about 8 months forgermination to commence, and some 35-70 d more to achieve itfully; such seeds must remain in moist ground all this time.A poorly developed embryo, little more than a hyaline mass ofcells, was all that could account for the delayed germination.Inhibition by extracts of seed parts was negligible. In A. crassifloraafter-ripening is related more to morphological changes in theembryo than to chemical changes. As the seed cannot endure evena brief sojourn in dry soil, vegetative reproduction is themeans by which the tree spreads into new areas.     

濒危植物中甸刺玫种子休眠及其生态学意义

对中甸刺玫Rosa praelucens种子结构及其透水性,赤霉素处理对胚的影响,果壳、种皮、胚乳的粗提物活性进行研究。结果表明：(1) 中甸刺玫外种皮是由多层排列紧密的厚壁细胞组成,内种皮为坚硬致密的栅栏组织;(2) 种皮对种子的吸胀阻碍较大, 未处理的种子吸水率较低,吸水13 d后增加量为18.82%;(3) 果实结籽率为0.69%,多数果实中没有饱满的种子;(4) 赤霉素100 mg·kg-1预处理种子可加快胚的萌发速率;(5) 胚乳、种皮、果壳中存在内源抑制物。中甸刺玫种子的休眠是由其形态和生理特点引起的综合休眠。     

Hormonal Regulation of Dormancy in Developing Sorghum Seeds

The role of abscisic acid (ABA) and gibberellic acid (GA) in determining the dormancy level of developing sorghum (Sorghum bicolor [L.] Moench.) seeds from varieties presenting contrasting preharvest sprouting behavior (Redland B2, susceptible; IS 9530, resistant) was investigated. Panicles from both varieties were sprayed soon after pollination with fluridone or paclobutrazol to inhibit ABA and GA synthesis, respectively. Fluridone application to the panicles increased germinability of Redland B2 immature caryopses, whereas early treatment with paclobutrazol completely inhibited germination of this variety during most of the developmental period. Incubating caryopses in the presence of 100 [mu]M GA4+7 overcame the inhibitory effect of paclobutrazol, but also stimulated germination of seeds from other treatments. IS 9530 caryopses presented germination indices close to zero until physiological maturity (44 d after pollination) in control and paclobutrazol-treated particles. However, fluridone-treated caryopses were released from dormancy earlier than control and paclobutrazol-treated caryopses. Incubation in the presence of GA4+7 stimulated germination of caryopses from all treatments. Our results support the proposition that a low dormancy level (which is related to a high preharvest sprouting susceptibility) is determined not only by a low embryonic sensitivity to ABA, but also by a high GA content or sensitivity.     

三裂叶野葛种子的休眠及萌发（简报）

２０mg.L^-1激动素（ＫＴ）浸种的三裂叶野葛种子萌发效果最佳,萌发率达７５％,用石英砂研靡破种皮后,再以２０mg.L^-1ＫＴ浸种的三裂叶野葛种子的萌发率达到９５％,提早５d萌发。根据种子抑制物实验的结果认为,三裂叶野葛种子的种皮和种仁中可能存在抑制种子萌发的物质。     

The Genus Syringa: Molecular Markers of Species and Cultivars

RAPD analysis was carried out with 22 accessions of the genus Syringa, including six species, one interspecific hybrid, and 15 cultivars. In total, 512 polymorphic fragments were detected; species-specific and cultivar-specific markers were identified. For the first time, genetic polymorphism and genome similarity coefficients were estimated and phylogenetic relationships were established for the genus Syringa.     

Ethylene Involvement in Dormancy Release of Ricinodendron rautanenii Seeds

Ricinodendron rautanenii (manketti) seeds respond to as littleas 10^–2 µl I^–1 ethylene. Both dry and imbibedseeds respond to ethylene treatments. The length of the imbibitionperiod prior to the ethylene treatment is not important as seedswhich were simultaneously gassed and imbibed germinated successfully.Seeds were sensitive to the gas at temperatures between 25 and35 °C. No temperature effect was observed in seeds whichwere transferred from temperatures below 20 °C, or above35 °C, to 30 °C. There is no period of carbon dioxidesensitivity associated with the ethylene treatment and the effectsof the ethylene treatment persisted in both dry and imbibedseeds when subsequently maintained (desiccated) at room temperaturefor 8 d Ricinodendron rautanenii, manketti nut, ethylene, germination     

Dormancy of Paddy Seeds of a 'Non-dormant' Variety

Seeds of a non-dormant rice variety, Satika, were studied underdifferent natural and controlled humid conditions of storageat room temperature. Just after harvest the germination andpercentages of grain moisture were 9.2 and 30.0 respectively.Under humid conditions of storage (94 per cent) there was onlypartial break of dormancy after 42 d (32.8 per cent ger mination)with high grain moisture (23.8 per cent); in all other treatmentswhere the grain moisture varied from 4.4 to 16.4 per cent thegermination percentages were over 96 per cent after 42 d. This delaying effect of high moisture contents on the breakingof dormancy became very pronounced at about 26 per cent. Itis suggested that high moisture content may inhibit dormancy-breakingreactions possibly by interrupting air-diffusion inside theseeds.     

Germination and Dormancy in Immature and Fresh-mature Lettuce Seeds

The effects of red light, far-red light, Gibberellin A₃, andethephon were studied on the germination of lettuce seeds cv.Grand Rapids harvested at different stages of development. Seeds did not become capable of germination until 8 days afteranthesis. Red light promoted seed germination from the age of8–9 days following anthesis up to the newly mature stage.Ten or 11 days following anthesis, a large percentage of seedsbecame capable of germination in the dark and therefore couldbe considered not dormant. They were affected by far-red light,but less so than the mature seeds. The effect of light on the germination of developing seeds appearedto be similar to the known light effect on mature lettuce seedgermination. Gibberellin A₃ and ethephon had no effect on immatureand fresh seed germination. Lactuca sativa L., Lettuce, germination, dormancy, red light, far-red light, gibberellin A₃, ethephon     

A Technique for Determining Quantitative Expressions of Dormancy in Seeds

A method of quantifying the heterogeneity of dormancy withinseed populations is described. The method compares germinationresponses of unstratified and stratified seeds of Pinus taedaL. (loblolly pine). Mathematical functions were fitted to cumulativegermination curves of unstratified and stratified seeds andfunctions were integrated to determine areas beneath respectivecurves. The area between respective curves was calculated bydifference and was considered to be a measure of dormancy withinseed lots. The method may be used to help identify various controlsof seed dormancy. seed germination, stratification, germination curves, Pinus taeda, loblolly pine, dormancy     

低能离子注入对大豆种子吸胀冷害的影响

本文分别从浸种液中无机离子的浓度、可溶性糖的浓度以及溶液的pH值,研究了低能离子注入对大豆种子吸胀冷害的影响。结果发现一定剂量的氮离子注入大豆种子后,其无机离子、可溶性糖、酸性物质的泄漏量均有低于对照组的趋势,而且其长势好于对照组,说明离子注入能在一定程度上减轻大豆遭受的吸胀冷害。