羊草种子休眠机制及破除方法研究

羊草种子休眠程度深、发芽率低是限制栽培利用的重要因子.采用不同破除羊草种子休眠的方法,测定各处理对种子萌发的影响,以探索破除羊草种子休眠的有效途径.结果显示:(1)刺破种皮的裸种子较完整种子的萌发率、吸水速率、生活力分别由对照的6%、63%、0%显著增加到60%、86%、94%.(2)完整羊草种子分别用清水浸种1 d、30% NaOH浸种80 min、清水浸种1 d后用30% NaOH浸种60min其萌发率由6%分别显著提高到36%、60%、84%,而各浓度赤霉素处理完整种子其萌发率较对照均无显著变化. (3)采用清水浸种1 d后用30% NaOH处理60 min,再施加200 μg/g GA3综合处理,可使羊草完整种子的发芽率由6%提高到91%,接近其种子生活力94%.研究表明,羊草种子的稃与种皮不影响种子水分的吸收,但影响种子对GA3的吸收、不同程度地阻碍大分子物质的渗入、限制羊草种子内部萌发抑制物的渗出,从而引起种子休眠;分析认为稃和种皮以及种子内部萌发抑制物质是引起羊草种子休眠的主要原因.     

东京野茉莉种子休眠机制及其破除方法初探

以采自江西吉安官山林场5年生东京野茉莉当年自然带壳种子为材料,通过对其种子吸水率、不同层积时期种子内生理生化指标的测定、种子萌发抑制物分析,并利用各类不同药剂处理进行发芽试验,以探寻东京野茉莉种子的休眠机理及破眠方法。结果表明:(1)休眠的原因主要包括种皮障碍、缺少萌发所需激素以及种皮、胚中存在萌发抑制物,其中种皮障碍和抑制物的存在是限制种子萌发的首要因素。(2)GA3处理结合自然低温层积30d即可解除东京野茉莉种子胚的休眠,但种皮障碍始终是其种子萌发的限制因素。(3)GA3、NAA、6-BA等药剂处理均可促进种子的萌发,并以刻伤种子后用500mg/L GA3处理24h为破除该种子休眠的最有效方法。     

绞股蓝种子休眠机理及其破除方法研究

以采自广西金秀县的绞股蓝种子为研究材料,对其休眠原因、休眠类型及其破眠方法进行了研究,为绞股蓝种子繁殖提供理论依据和技术支持。结果表明:(1)绞股蓝新采收成熟种子的生活力达91%,在10℃~35℃恒温和15℃/25℃变温中的发芽率均低于10%,新种子的生活力极显著大于发芽率,具有显著的休眠现象。(2)绞股蓝种皮不限制吸水,胚分化发育完全,离体胚发芽率为(78.0±4.8)%,且能够长成正常幼苗,说明绞股蓝种子的胚在离体条件下无休眠现象。(3)绞股蓝完整种子及其粉碎种子的水提液对白菜种子的萌发率、苗高及根长均有抑制作用,随水提液浓度增加抑制作用均显著增强,且粉碎种子的抑制作用较强;当粉碎种子的水提液浓度为5%时白菜种子萌发率、苗高、根长分别为18.0%、0.1cm、0.1cm,分别显著低于对照77.1%、97.3%、95.8%,说明绞股蓝种子的种皮和胚乳中存在水溶性萌发抑制物质,是绞股蓝种子休眠的主要原因。(4)GA3和6-BA不能促进绞股蓝种子萌发,低温层积对绞股蓝种子休眠的解除具有促进作用;绞股蓝种子的休眠属于生理休眠类型,休眠水平属于中间型。(5)低温干藏能够打破绞股蓝种子休眠,是绞股蓝种子破除休眠及种子保存较为理想的方式。     

麻花秦艽种子休眠机理及其破除方法

通过对干燥贮藏后熟麻花秦艽种子透水性和粗提物活性的测定以及采用高锰酸钾、赤霉素、青霉素、硫酸、流水浸泡方法进行发芽试验,探讨了种子休眠机理和破除休眠的技术。结果表明:麻花秦艽种子吸水过程符合Logistic曲线,其种皮对种子吸水无阻碍作用;硫酸和高锰酸钾处理极显著提高了麻花秦艽种子的发芽率(P<0.01),说明种皮机械障碍是种子萌发的因素之一。种子粗提物在浓度为0.02—0.2 g/mL时具有很强的抑制活性,均对小麦、白菜和麻花秦艽种子萌发和生长产生抑制作用以及流水浸泡可以提高麻花秦艽种子发芽率,表明种子内源抑制物是影响其休眠的另一因素。不同处理均打破了种子休眠,显著提高了种子发芽率,其中1.5%高锰酸钾浸泡10 min光照培养下种子发芽率及发芽势、发芽指数和活力指数均显著高于其他处理(P<0.05)。相比对照,1.5%高锰酸钾处理的种子发芽率极显著提高106.9%。经1.5%高锰酸钾浸泡10 min的麻花秦艽种子粗提物对白菜种子萌发的抑制作用低于未处理,以浓度为0.02—0.04 g/mL时抑制显著,说明高锰酸钾可减弱麻花秦艽种子内源抑制物的活性。综上所述,麻花秦艽种子的休眠属综合休眠。     

多刺绿绒蒿种子休眠及破除方法

通过对多刺绿绒蒿种子透水性和浸提物活性的测定及流水、600mg/L GA、100mg/L IAA、150mg/L PEG、800 g/mL GA和0.5 mmol/L SA浸泡后进行发芽实验,探讨种子休眠机理和破眠方法。结果表明:多刺绿绒蒿种子吸水符合一般种子吸水规律,说明其种皮对种子吸水无阻碍作用;GA和SA处理极显著提高了多刺绿绒蒿种子的发芽率(P<0.01),说明生理休眠是种子萌发的因素之一。多刺绿绒蒿水提物对小麦和白菜种子萌发的抑制作用极显著高于对照组和醇提液处理组,说明多刺绿绒蒿种子中所含抑制物主要为水溶性成分;种子水提物在浓度为0.04～0.20 g/mL时具有很强的抑制活性,均对小麦、白菜和多刺绿绒蒿种子萌发和生长产生抑制作用,以及流水浸泡可以提高多刺绿绒蒿种子发芽率,表明种子内源抑物是影响其休眠的另一因素。不同处理均可打破种子休眠,显著提高种子发芽率,其中600 g/mL GA浸泡24h黑暗培养下种子发芽率和发芽势均显著高于其他处理(P<0.05)。多刺绿绒蒿种子中存在活性较强的内源抑制物,且多为水溶性成分,具有一定的生理休眠特性。     

野生鸭儿芹种子休眠特性及破除方法

鸭儿芹种子具有休眠特性,且休眠期长,不经任何处理的种子很难萌发,影响其人工种植。研究了鸭儿芹种子的休眠特性和解除休眠的最佳方法,为我国人工种植野生鸭儿芹提供理论依据。结果表明:TTC法对种子活力的测定表明有活力的种子为(55.33±3.71)%;切破种皮种子与完整种子吸水率在前12 h相差较大,但最终吸水率相差不大,分别达到(70.00±1)%和(68.32±0.32)%,表明种皮并不阻碍种子吸水;种子中存在内源抑制物,其粗提液在较低浓度下即可抑制芹菜种子的萌发;鸭儿芹种子成熟时胚未分化完全,胚率为(28.65±2.488)%,经过低温处理后完成后熟,胚率达到(65.93±3.86)%,萌发率达到100%,因此鸭儿芹种子具有形态生理休眠特性。清水浸种和低温冷藏共同处理可有效解除其休眠,浸种和低温冷藏具有交互效应,浸种36 h、5℃冷藏30d即可解除其休眠,萌发率达到100%,发芽势达到(91.11±0.91)%。已破除休眠的种子适宜其萌发的温度范围扩大(15.0—27.5℃),而且在土壤中也可较好地萌发,萌发率达到(96.67±3.33)%,发芽势达到(71.11±1.93)%。     

浅述林木种子休眠的解除方法

种子休眠是植物经长期演化获得的一种对环境条件及季节性变化的生物学适应性。生产中林业工作者必须根据种子休眠的不同类型而采用相应解除种子休眠的方法,以便更好地培育苗木。文章对解除林木种子休眠的破皮法和催芽法作了详细介绍     

种子休眠机理研究概述

种子休眠是植物本身适应环境和延续生存的一种特性,是种子植物进化的一种稳定对策。野生植物特别是原产温带的植物,其种子大多有深而长的休眠期。关于种子休眠的概念有多种,这些概念引出了许多学说、假说和模型。种壳障碍、胚形态发育不完全和生理后熟以及种子中含有化学抑制剂等,都可导致种子休眠。根据不同的分类标准可将种子分成不同类型,一般将种子分为强迫休眠和机体休眠;机体休眠又可分为外部休眠、内部休眠和综合休眠。植物种类不同休眠特性也不同;同种植物的种子来源于不同的居群和植株时,若采集时期不同,其休眠也可能不同;甚至在同一果实中的不同种子,休眠特性亦可能有差异。影响休眠性状表达的基因既有核基因,也有质基因,休眠通常表现为一种受多基因控制的数量性状。种子休眠具有重要的生态学意义,能有效地调节种子萌发的时空分布。研究种子的休眠特性和机理及其解除方法,有助于农业生产和植物多样性保护。     

草玉梅种子休眠原因及解除休眠方法

为明晰草玉梅(Anemone rivularis)种子的休眠类型和破除休眠的方法、为草地改良和草玉梅的栽培提供基础,以未去除果皮的草玉梅瘦果为对照,研究了不同处理对草玉梅种子休眠的影响。结果表明:40~50 g·L-1的NaOH溶液浸泡3~5 h未能破除其休眠;经过2个月的贮藏,剪去草玉梅果皮上端、除去果皮的草玉梅种子在黑暗条件下的发芽率分别为3.3%和6.2%,与对照(2.0%)差异不显著(P0.05),而光照条件下的上述种子发芽率分别为38.7%和76.0%,显著高于对照(P0.05);剪去果皮基部的草玉梅种子在光照和黑暗条件下的发芽率与对照差异不显著(P0.05)。除去部分(1/5~1/4)果皮能使草玉梅种子发芽率提高到62.7%,显著高于对照(P0.05);果皮穿刺处理显著提高了草玉梅种子发芽率(19.3%)(P0.05),但显著低于除去果皮和部分去皮处理(P0.05);草玉梅果皮水提液对草玉梅种子萌发无抑制作用;10~30 mg·L-1GA3浸泡处理10 h未能提高草玉梅瘦果的发芽率;草玉梅种子在25/15℃变温条件下发芽率最高,15/5℃和10/5℃变温条件下不能发芽。综合分析认为,果皮的遮光引起了草玉梅种子的休眠,除去果皮能有效破除草玉梅种子的休眠。除去果皮后尚有部分种子仍然处于休眠状态,因此草玉梅种子(瘦果)的休眠为综合休眠类型。     

不同处理对银沙槐种子休眠破除和幼苗生长的影响

对银沙槐种子破除休眠的适宜方法及其幼苗生长进行研究。结果表明:破口和沙磨处理休眠破除效果最好,但容易引起种子腐烂死亡;分别用65、80和95℃热水处理种子,以95℃1 min破除种子休眠效果最好,且幼苗长势好,65℃效果最差,80℃可破除部分种子休眠,除80℃外延长热水处理时间可导致死种子数增加,95℃则引致大部分种子死亡;液氮浸种处理效果均显著,其中以液氮处理10 min效果最好,但幼苗多为不正常苗而致死;硫酸处理以浸种120 min效果最好,但处理时间过长可导致死种子数增多,且造成少数幼苗根部腐蚀死亡。综上所述,打破银沙槐种子休眠的较优处理方法是硫酸120 min浸种处理和95℃1 min热水处理。     

豆科植物种子物理性休眠解除机制的研究进展

物理性休眠普遍存在于豆科植物种子中,其休眠解除机制的研究对阐明自然条件下种群的繁殖更新、生态环境恢复及种质资源的保存等都具有重要意义.本文对国内外关于影响种子休眠解除的环境因素(温度与温度的波动、湿度或土壤含水量)和生物因素(动物捕食、微生物感染等),休眠解除的结构基础,以及各种因子作用于种子的方式和部位的研究进展进行综述,并简要评述了休眠解除机制的二阶段和四阶段假说,以期为豆科植物种子休眠的进一步研究提供参考.     

Germination of Prosopis juliflora (Sw) DC seeds after scarification treatments

Invasive plant species are the second most important threat to global biodiversity loss after land‐use change. Invasive species can modify native community composition, deplete species diversity and affect ecosystem processes. The Caatinga is one of the most human‐affected Brazilian ecosystems owing to non‐sustainable use of its natural resources. Prosopis juliflora is an important invasive plant species in the Caatinga ecosystem. Seed germination is a critical stage in plant life cycles and is a major factor in the establishment and success of invasive plant species. Among the factors that affect seed germination and dormancy, coat‐imposed seems to be the most important for P. juliflora. In Prosopis species, the ingestion of fruits by wild and domestic animals may promote and accelerate germination, enhancing the dispersal of seeds and fruits of these species. We investigated the germination capacity of P. juliflora seeds after artificial mechanical and chemical scarification and analyzed the changes in seedling vigor caused by the scarification treatments. Germination rate, germination time (TMG) and germination synchrony (E) differed significantly with the length of the scarification treatments in H₂SO₄ for both seeds with endocarps and seeds without endocarps (non‐endocarp seeds). Sulfuric acid affected plant survival more strongly than germination rate, particularly in non‐endocarp seeds.     

莎草科4种植物种子休眠与萌发特性的研究

以嵩草、黑穗苔草、藨草和苔草4种莎草科植物种子为材料,研究了硫酸、植物生长调节剂及低温层积处理对其休眠与萌发特性的影响,以揭示其休眠机制及其破除方法,为指导生产提供理论依据。结果表明:(1)4种参试植物种子均存在不同程度的生理休眠,其中嵩草为浅度生理休眠,黑穗苔草为中度生理休眠,藨草和苔草为深度生理休眠。(2)浓硫酸浸种可显著提高嵩草、黑穗苔草种子的萌发,随浸种时间增加,种子萌发率先增加后降低,最大值分别达86%、77%,但浓硫酸处理对藨草和苔草的种子萌发无显著促进作用。(3)赤霉素(GA3)、氟啶酮(FL,脱落酸抑制剂)和KNO3单独处理可显著提高嵩草种子萌发,但对其他3种植物种子无显著作用;而硫酸处理后再用赤霉素或氟啶酮处理,则显著促进黑穗苔草种子的萌发率。(4)低温层积对种子萌发的影响因种与层积时间而异,层积2个月可显著提高嵩草种子萌发,层积4个月可显著提高嵩草和藨草种子萌发;层积6个月可显著提高嵩草、黑穗苔草、藨草和苔草4种植物种子萌发,其最终萌发率分别为90%、73%、17%、7%。     

Variation in the Amino Acid Concentration During Development of Canavalia ensiformes

The distribution of amino acids in distinct tissues of Canavalia ensiformes was determined during the life cycle of the plant. Glycine was shown to be the main amino acid in mature seeds, while the nonprotein amino acid canavanine exhibited a high concentration in 7-d-old seedlings. Canavanine was lower in the seeds when compared to other tissues analyzed. This does not support the nitrogen-storage function of canavanine, however, it suggests that it is involved in the translocation of amines during the early stages of the development. This revised version was published online in July 2006 with corrections to the Cover Date.     

Combinational dormancy in seeds of Sicyos angulatus (Cucurbitaceae,tribe Sicyeae)

Seeds with a water‐impermeable seed coat and a physiologically dormant embryo are classified as having combinational dormancy. Seeds of Sicyos angulatus (burcucumber) have been clearly shown to have a water‐impermeable seed coat (physical dormancy [PY]). The primary aim of the present study was to confirm (or not) that physiological dormancy (PD) is also present in seeds of S. angulatus. The highest germination of scarified fresh (38%) and 3‐month dry‐stored (36%) seeds occurred at 35/20°C. The rate (speed) of germination was faster in scarified dry‐stored seeds than in scarified fresh seeds. Removal of the seed coat, but leaving the membrane surrounding the embryo intact, increased germination of both fresh and dry‐stored seeds to > 85% at 35/20°C. Germination (80–100%) of excised embryos (both seed coat and membrane removed) occurred at 15/6, 25/15 and 35/20°C and reached 95–100% after 4 days of incubation at 25/15 and 35/20°C. Dry storage (after‐ripening) caused an increase in the germination percentage of scarified and of decoated seeds at 25/15°C and in both germination percentage and rate of excised embryos at 15/6°C. Eight weeks of cold stratification resulted in a significant increase in the germination of scarified seeds at 25/15 and 35/20°C and of decoated seeds at 15/6 and 25/15°C. Based on the results of our study and on information reported in the literature, we conclude that seeds of S. angulatus not only have PY, but also non‐deep PD, that is, combinational dormancy (PY + PD).     

Wet-season dormancy release in seed banks of a tropical leguminous shrub is determined by wet heat

BACKGROUND AND AIMS: Hard-seeded (physical) dormancy is common among plants, yet mechanisms for dormancy release are poorly understood, especially in the tropics. The following questions are asked: (a) whether dormancy release in seed banks of the tropical shrub Parkinsonia aculeata (Caesalpiniaceae) is determined by wet heat (incubation under wet, warm to hot, conditions); and (b) whether its effect is modified by microclimate. METHODS: A seed burial trial was conducted in the wet-dry tropics (northern Australia) to compare dormancy release across different habitats (open, artificial cover, ground cover and canopy cover), burial depths (0, 3 and 20 cm) and burial durations (2, 6 and 14 weeks). Results were compared with predictions using a laboratory-derived relationship between wet heat and dormancy release, and microclimate data collected during the trial. KEY RESULTS: Wet heat (defined as the soil temperature above which seeds were exposed to field capacity or higher for a cumulative total of 24 h) was 43.6 degrees C in the 0 cm open treatment, and decreased with increasing shade and depth to 29.5 degrees C at 20 cm under canopy cover. The dormancy release model showed that wet heat was a good predictor of the proportion of seeds remaining dormant. Furthermore, dormancy release was particularly sensitive to wet heat across the temperature range encountered across treatments. This resulted in a 16-fold difference in dormancy levels between open (<5 % of seeds still dormant) and covered (82 %) microhabitats. CONCLUSIONS: These results demonstrate that wet heat is the principal dormancy release mechanism for P. aculeata when conditions are hot and wet. They also highlight the potential importance of microclimate in driving the population dynamics of such species.     

Phylogeny of seed dormancy in Convolvulaceae, subfamily Convolvuloideae (Solanales)

Background and Aims: The water gap is an important morphoanatomical structure inseeds with physical dormancy (PY). It is an environmental signaldetector for dormancy break and the route of water into thenon-dormant seed. The Convolvulaceae, which consists of subfamiliesConvolvuloideae (11 tribes) and Humbertoideae (one tribe, monotypicHumberteae), is the only family in the asterid clade known toproduce seeds with PY. The primary aim of this study was tocompare the morphoanatomical characteristics of the water gapin seeds of species in the 11 tribes of the Convolvuloideaeand to use this information, and that on seed dormancy and storagebehaviour, to construct a phylogenetic tree of seed dormancyfor the subfamily. Methods: Scanning electron microscopy (SEM) was used to define morphologicalchanges in the hilum area during dormancy break; hand and vibratomesections were taken to describe the anatomy of the water gap,hilum and seed coat; and dye tracking was used to identify theinitial route of water entry into the non-dormant seed. Resultswere compared with a recent cladogram of the family. Key Results: Species in nine tribes have (a) layer(s) of palisade cells inthe seed coat, a water gap and orthodox storage behaviour. Erycibe(Erycibeae) and Maripa (Maripeae) do not have a palisade layerin the seed coat or a water gap, and are recalcitrant. The hilarfissure is the water gap in relatively basal Cuscuteae, andbulges adjacent to the micropyle serve as the water gap in theConvolvuloideae, Dicranostyloideae (except Maripeae) and theCardiochlamyeae clades. Seeds from the Convolvuloideae havemorphologically prominent bulges demarcated by cell shape inthe sclereid layer, whereas the Dicranostyloideae and Cardiochlamyeaehave non-prominent bulges demarcated by the number of sub-celllayers. The anatomy and morphology of the hilar pad follow thesame pattern. Conclusions: PY in the subfamily Convolvuloideae probably evolved in theaseasonal tropics from an ancestor with recalcitrant non-dormantseeds, and it may have arisen as Convolvulaceae radiated tooccupy the seasonal tropics. Combinational dormancy may havedeveloped in seeds of some Cuscuta spp. as this genus movedinto temperate habitats.     

苦槠传播体的萌发特性与种子休眠类型

种子的萌发特性是植物在长期进化过程中形成的一种适应环境变化的固有属性。对种子萌发特性的研究有助于我们理解物种的种群更新和种子育苗。本文旨在阐明我国重要资源植物苦槠（Castanopsis sclerophylla）的种子休眠类型和萌发特性。研究结果发现：①苦槠种子在其果实中占比非常高;②苦槠的果皮限制了种子对水分的吸收;③苦槠果皮阻碍了种子的萌发,除去果皮以后种子能够在较大温度范围内萌发;④除去果皮以后,苦槠种子在低温（15/5 ℃、20/10 ℃）下萌发困难,在25/15 ℃、30/20 ℃和35/25 ℃这3个温度梯度下均能迅速萌发。结果表明,苦槠的传播体（果实）具有物理休眠的特性。因此,壳斗科（Fagaceae）是具有物理休眠和脱水敏感性的一个新纪录科。结合壳斗科的系统发育位置,本研究支持物理休眠是一种较为进化的性状这一假说。     

The effectiveness and competitiveness of some Indonesian Rhizobium strains on tropical legumes grown in four soil types of Java

Several Indonesian and some imported Rhizobium strains were assessed for their effectiveness in nodulating four legume species in four soil types of Java. Naturally occurring Rhizobia formed effective symbioses onVigna unguiculata, Macroptilium atropurpureum andDesmodium heterocarpon in all four soils and the applied strains, with some exceptions, did not infect a majority of nodules of these legumes.Centrosema pubescens was more specific in its Rhizobia requirements and applied strains formed effective symbioses in two clay soils, but not in two sandy loam soils.