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.     

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。     

桃儿七种子解剖结构及其萌发生长期形态特征

为探明种皮和胚乳是否是限制桃儿七种子萌发的主要因素,利用组织切片和显微技术,对桃儿七种子及其不同萌发期（1、7、14、21、28 d）解剖结构和播种后一定时期内（7~210 d）的植株生长形态进行观察。桃儿七种子由种皮、胚乳和胚构成。种皮包括外种皮和内种皮,外种皮致密规整,由外至内分别为栅状石细胞和表皮层细胞,内种皮由5~6层海绵细胞组成。胚乳占种子体积的绝大部分,包括珠孔胚乳和外胚乳。胚由胚根、胚轴和子叶组成,被致密种皮、多层珠孔胚乳和外胚乳包围。萌发期1~7 d胚根和胚轴开始伸长,7~14 d两片子叶分离,14~21 d胚根突破珠孔胚乳和种皮,21~28 d胚根、胚轴和子叶继续扩张伸长。种子播种210 d后可平均形成3片功能真叶和5条不定根。致密种皮（物理休眠）和多层胚乳（机械休眠）是限制桃儿七种子萌发的两个主要因素。     

准噶尔山楂种壳、种皮、种胚特性与种子休眠的关系

以准噶尔山楂种子为试验材料,检测其种壳和种皮的透水性及超微结构、种胚休眠特性及种子浸提液的抑制作用。结果表明：（1）准噶尔山楂种子具有胚休眠特性,种壳存在一定的机械束缚和透水障碍,存在内源抑制物质是引起准噶尔山楂种子休眠的主要原因。（2）酸蚀处理能使种壳表面结构破损,角质层脱落,种壳变薄,栅栏组织结构和细胞排列未发生变化,种孔增大,种子表面出现裂缝,但并不影响种子生活力。（3）准噶尔山楂种子甲醇浸提液的生物测定结果说明,准噶尔山楂种子的种壳、种皮和种胚均含有内源抑制物质,不同部位浸提液对白菜种子的发芽率、根长和苗高的抑制作用不同。     

穿龙薯蓣种子休眠机理的初步研究

通过不同试验处理初步确定了穿龙薯蓣种子休眠的主要原因并通过试验寻找出了破除休眠的方法.结果表明:通过去皮露胚处理的种子发芽率无明显提高,说明穿龙薯蓣种子不具有种皮抑制吸水障碍性休眠;通过穿龙薯蓣种子和种子翼翅不同溶剂提取液对白菜种子发芽率的影响试验表明穿龙薯蓣种子和种子翼翅中含有抑制发芽物质.在确定穿龙薯蓣种子休眠原因后,通过不同试验处理,寻找到了合理破除种子休眠的方法.结果表明:在破除休眠试验中以0～5℃低温层基处理4周和100 mg/kg赤霉素浸种24 h效果最佳.     

珍稀濒危植物蒜头果种子萌发特征与幼苗类型的研究

以去除果皮后阴干的珍稀濒危植物蒜头果种子为材料,在温室大棚沙池内进行层积处理,从层积处理开始至子叶出土的不同萌发阶段,考察蒜头果种子发育形态、贮藏物质积累、酶活性以及幼苗类型等变化特征,初步探讨其种子休眠形成原因。结果显示：(1)蒜头果种子从解除休眠开始至萌发形成幼苗的过程约需195 d,其中幼胚的形态发育后熟约需75 d,随后30 d内是种子集中萌发的时期,其发芽率达到最高(53.33%);依据种胚发育形态的标志特征将此过程划分为7个阶段(S1～S7阶段):S1阶段种子未萌发,S2阶段种胚“露白”,S3阶段胚根突破种皮长超过1 cm, S4阶段下胚轴与胚根连接处形成弯钩结构,S5阶段“S”型胚形成及胚根前端膨大,S6阶段种子不仅具有膨大的胚根且已有侧根的分化,S7阶段子叶脱落,胚芽出土,真叶出现。(2)蒜头果种子在湿沙层积过程中,种胚胚长和胚率从S1阶段的(5.49±1.57)mm和(19.48±5.72)%分别增加至S6阶段的(67.92±2.94)mm和(240.75±15.29)%,胚率平均增加了12.4倍,显示蒜头果种子的胚需要经历后熟过程才能萌发,属于胚后熟型种子。(3)从...     

沙葱种皮特性、种胚及种子浸提液与种子休眠的关系

本文以沙葱休眠种子为试材,检测其种皮透水性、透气性、超微结构、种胚休眠及种子浸提液。结果表明,酸蚀种子吸水12h达饱和,吸水率是完整种子的2倍;其呼吸强度最大值是完整种子的1.36倍。酸蚀处理使种子表面结构破损,角质层脱落,种孔露出。沙葱种子离体胚接种培养后2～3d,种胚开始萌发,萌发率达85％。沙葱完整种子与粉碎种子的浸提液对白菜种子发芽率、苗高、根长均有抑制作用,且随着浓度的提高而增强。     

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。     

5种野生无髯鸢尾种子休眠与萌发特性研究

以5种野生无髯鸢尾种子为材料,从种子的吸水率和发芽率两个方面分析休眠原因与打破休眠促进萌发的方法,为中国鸢尾属植物的种质资源保护与应用提供技术支持。结果表明:(1)5种野生无髯鸢尾种子的吸水率比较显示,玉蝉花和山鸢尾的种皮透水性最好,其次是燕子花的种皮透水性,溪荪的种皮透水性最差;种皮的透水、透气性差及致密的胚乳是抑制马蔺种子萌发的主要原因;另外,变温可增加野生无髯鸢尾种子种皮和胚乳的透水性。(2)马蔺和溪荪种子的种皮对萌发存在强烈的抑制作用,而燕子花、山鸢尾和玉蝉花种子的种皮抑制作用不显著;珠孔端胚乳是5种野生鸢尾种子休眠的主要因素。(3)温度对5种野生无髯鸢尾种子萌发影响很大,变温处理显著提高了马蔺、溪荪、玉蝉花种子的萌发率,且最适条件为:变温30℃/20℃、8h光照/16h黑暗,但该条件对山鸢尾和燕子花种子萌发的影响不显著,即单一因子不能打破燕子花和山鸢尾种子的休眠。研究发现,5种野生无髯鸢尾种子休眠和萌发特征各异,主要影响因素也不尽相同,但珠孔端胚乳是5种野生无髯鸢尾种子休眠的主要因素;低温层积处理与变温30℃/20℃相结合能明显提高野生无髯鸢尾属种子的发芽率,是其种子打破休眠的有效措施。     

裕民贝母种子形态休眠解除过程中的形态学研究

为掌握裕民贝母种子休眠的形态响应机制,判断外源GA_3能否有效解除种子形态休眠,对CK和GA_3:30 mg/L处理下种子的形态结构及亚微结构变化规律进行比较。结果表明:(1)GA_3:30 mg/L处理下种子的形态休眠时间为60 d,比CK处理提前20 d,胚率从22.33%提高到87.67%,然后种子进入生理休眠阶段;(2)种子具翅,质轻型小,胚完成形态休眠后结构分化仍不明显;(3)随种子形态休眠的打破,种皮颜色不断加深,胚乳不断水解,胚不断生长发育,胚率提高至恒定;(4)随种子形态休眠的解除,种皮气孔器结构稳定,但叶绿体数量持续增加,种皮、胚乳及胚的亚微结构变化不明显,仅胚乳表皮细胞破损严重。     

Epicotyl morphophysiological dormancy in seeds of Lilium polyphyllum (Liliaceae)

Dormancy-breaking and seed germination studies in genus Lilium reveal that the majority of Lilium spp. studied have an underdeveloped embryo at maturity, which grows inside the seed before the radicle emerges. Additionally, the embryo, radicle or cotyledon has a physiological component of dormancy; thus, Lilium seeds have morphophysiological dormancy (MPD). A previous study suggested that seeds of Lilium polyphyllum have MPD but the study did not investigate the development of the embryo, which is one of the main criteria to determine MPD in seeds. To test this hypothesis, we investigated embryo growth and emergence of radicles and epicotyls in seeds over a range of temperatures. At maturity, seeds had underdeveloped embryos which developed fully at warm temperature within 6 weeks. Immediately after embryo growth, radicles also emerged at warm temperatures. However, epicotyls failed to emerge soon after radicle emergence. Epicotyls emerged from >90% seeds with an emerged radicle only after they were subjected to 2 weeks of cold moist stratification. The overall temperature requirements for dormancy-breaking and seed germination indicate a non-deep simple epicotyl MPD in L. polyphyllum.     

Underdeveloped embryos and germination in Aristolochia galeata seeds

Aristolochiaceae have been described as having seeds with underdeveloped embryos and morphological or morphophysiological dormancy. Aristolochia galeata is a native climber found in the Cerrado biome, associated with road and gallery forest edges. The aims of this study were to investigate: embryo growth rate, morphology and seed germination parameters under different treatments. Embryos were excised to obtain embryo length at four stages: initial, seeds after coat rupture, radicle tip protrusion and cotyledon emergence from the seed coat. Germination tests were conducted at 30 °C under three nitrate concentrations (1, 10 and 20 mM), fluctuating temperature (27/20 °C) and light and dark conditions. We found that seeds have underdeveloped embryos, which take about 301 ± 178 h (±SD) to achieve seed coat rupture, another 205 ± 126 h to reach radicle protrusion and 176 ± 76 h more to the final stage of cotyledon emergence. Germinability was above 52% in all treatments, except in the dark (15%). For all treatments, average germination time was above 290 ± 123 h. Potassium nitrate increased germinability to >87%. No particular treatment was required for embryo development, but seeds in the population that continued to germinate after 1 month were probably in various states of non-deep, simple morphophysiological dormancy. Increased germinability in nitrate treatments and light requirement for germination could prevent germination under unsuitable environmental conditions and be a strategy to increase seedling establishment in the cerrado.     

Physiology, morphology and phenology of seed dormancy break and germination in the endemic Iberian species Narcissus hispanicus (Amaryllidaceae)

Background and Aims

Only very few studies have been carried out on seed dormancy/germination in the large monocot genus Narcissus. A primary aim of this study was to determine the kind of seed dormancy in Narcissus hispanicus and relate the dormancy breaking and germination requirements to the field situation.

Methods

Embryo growth, radicle emergence and shoot growth were studied by subjecting seeds with and without an emerged radicle to different periods of warm, cold or warm plus cold in natural temperatures outdoors and under controlled laboratory conditions.

Key Results

Mean embryo length in fresh seeds was approx. 1·31 mm, and embryos had to grow to 2·21 mm before radicle emergence. Embryos grew to full size and seeds germinated (radicles emerged) when they were warm stratified for 90 d and then incubated at cool temperatures for 30 d. However, the embryos grew only a little and no seeds germinated when they were incubated at 9/5, 10 or 15/4 °C for 30 d following a moist cold pre-treatment at 5, 9/5 or 10 °C. In the natural habitat of N. hispanicus, seeds are dispersed in late May, the embryo elongates in autumn and radicles emerge (seeds germinate) in early November; however, if the seeds are exposed to low temperatures before embryo growth is completed, they re-enter dormancy (secondary dormancy). The shoot does not emerge until March, after germinated seeds are cold stratified in winter.

Conclusion

Seeds of N. hispanicus have deep simple epicotyl morphophysiological dormancy (MPD), with the dormancy formula C_1bB(root) – C₃(epicotyl). This is the first study on seeds with simple MPD to show that embryos in advanced stages of growth can re-enter dormancy (secondary dormancy).     

The Effect of Stratification on the Endogenous Cytokinin Levels of Seed of Protect compacta and Leucadendron daphnoides

The soybean callus assay was used to study the effect of stratification on the cytokinin levels of the embryo dormant seed of Protea compacta R.Br. and the seed of Leucadendron dapbnoides Meisn., where dormancy is coat imposed. Chilling the seed for 30 days increased germination significantly, and resulted in a simultaneous increase in the butanol soluble cytokinins of both species. It would appear as if these compounds are either synthesized or released from a bound form in embryo dormant seed. In contrast, an interconversion from water soluble to butanol soluble cytokïnins appears to account for the increase where dormancy is coat imposed. The results also indicate that for germination to take place a threshold concentration of cytokinin may be required. It is suggested that the increase in butanol soluble cytokinins may lead to the breaking of dormancy, probably by increasing radicle elongation and/or cotyledon expansion.     

The Effect of Oxygen on Endogenous Cytokinin Levels and Germination of Leucadendron daphnoides Seed

The soybean callus assay was used to study the effect of high oxygen tensions on the cytokinin levels of Leucadendron daphnoides Meisn. seed, where dormancy is apparently due to the restricting effect of the seed coat on oxygen diffusion to the embryo. High oxygen tensions led to a six-fold increase in germination compared to seed incubated in air and resulted in significant increases in butanol soluble cytokinins prior to visible germination. It is suggested that the primary effect of oxygen is to increase the rate of respiration and thus, to provide the energy required for the synthesis of butanol soluble cytokinins which leads to cotyledon expansion and subsequent radicle elongation. Present indications are that untreated seeds remain dormant due to low concentrations of butanol soluble cytokinins in their embryos.     

濒危植物桃儿七种子休眠特性的研究

桃儿七种子在自然条件下具有休眠期长、萌发不良的生理特性,为了探讨和研究桃儿七种子的休眠特性,利用分离胚培养、生物鉴定法、GA₃浸种、以及综合利用GA₃和低温层积处理等方法。结果表明：种皮和胚乳的限制以及生理后熟是引起桃儿七种子休眠的主要原因,用400 mg·L^-1的GA₃溶液浸种24 h或低温层积后用GA₃处理均能在一定程度上解除休眠促进萌发,其中以低温层积90 d后用500 mg·L^-1的GA₃浸种36 h效果最好,发芽率和发芽势分别达到81.11%和50.00%。     

黄精种子萌发过程发育解剖学研究

采用石蜡切片技术对成熟黄精种子形态及萌发过程中的形态学变化及解剖结构特征进行了研究,以阐明黄精种子繁殖的生物学机制。结果显示:(1)成熟的黄精种子由外而内依次为种皮、胚乳和胚等3部分组成。其中种皮由一层木质化的细胞组成;胚乳占据种子的大部分结构,胚乳细胞含有大量淀粉,细胞壁增厚;胚处于棒型胚阶段。(2)黄精种子在萌发过程中棒型胚靠近种脐端分化为吸器、子叶联结和子叶鞘,靠近种孔的部位分化出胚根、胚轴和胚芽。(3)黄精种子萌发首先由子叶联结伸长将胚芽和胚根原基推出种孔,紧接着下胚轴膨大形成初生小根茎,吸器留在种子中分解吸收胚乳中的营养物质。(4)通过子叶联结连通吸器和初生小根茎,将胚乳中的营养物质由吸器-子叶联结这个通路转移到初生小根茎中,为初生根茎上胚芽和胚根的进一步分化提供物质保障。(5)黄精种子自然条件下萌发率较低,而且当年不出土。研究表明,黄精种子的繁殖生物学特性是其生态适应的一种重要机制。     

Deep simple epicotyl morphophysiological dormancy in seeds of two Viburnum species, with special reference to shoot growth and development inside the seed

Background and Aims

In seeds with deep simple epicotyl morphophysiological dormancy, warm and cold stratification are required to break dormancy of the radicle and shoot, respectively. Although the shoot remains inside the seed all winter, little is known about its growth and morphological development prior to emergence in spring. The aims of the present study were to determine the temperature requirements for radicle and shoot emergence in seeds of Viburnum betulifolium and V. parvifolium and to monitor growth of the epicotyl, plumule and cotyledons in root-emerged seeds.

Methods

Fresh and pre-treated seeds of V. betulifolium and V. parvifolium were incubated under various temperature regimes and monitored for radicle and shoot emergence. Growth of the epicotyl and cotyledons at different stages was observed with dissecting and scanning electron microscopes.

Key Results

The optimum temperature for radicle emergence of seeds of both species, either kept continuously at a single regime or exposed to a sequence of regimes, was 20/10 °C. GA₃ had no effect on radicle emergence. Cold stratification (5 °C) was required for shoot emergence. The shoot apical meristem in fresh seeds did not form a bulge until the embryo had grown to the critical length for radicle emergence. After radicle emergence, the epicotyl–plumule and cotyledons grew slowly at 5 and 20/10 °C, and the first pair of true leaves was initiated. However, the shoot emerged only from seeds that received cold stratification.

Conclusions

Seeds of V. betulifolium and V. parvifolium have deep simple epicotyl morphophysiological dormancy, C_1bB (root)–C₃ (epicotyl). Warm stratification was required to break the first part of physiological dormancy (PD), thereby allowing embryo growth and subsequently radicle emergence. Although cold stratification was not required for differentiation of the epicotyl–plumule, it was required to break the second part of PD, thereby allowing the shoot to emerge in spring.     

栎属7种植物种子的发芽抑制物质研究

运用系统溶剂法和生物测定法,以栎属7种植物种子为材料,研究了其种皮、胚(胚及周围部分子叶)和子叶(远离胚端2/3子叶)1.0 g/mL和0.5 g/mL浓度甲醇等浸提液以及各有机相对白菜种子萌发的影响。结果表明:栓皮栎、锐齿栎、蒙古栎、沼生栎和麻栎甲醇浸提液均能显著降低白菜种子发芽率、根长和苗高,且对发芽率的抑制作用逐渐降低;夏栎和房山栎甲醇浸提液对白菜种子发芽率没有显著影响,但对根长和苗高有一定的抑制作用;种子不同部位甲醇浸提液的抑制作用表现为胚>子叶>种皮,且甲醇高浓度浸提液的抑制作用大于低浓度的抑制作用;甲醇相对白菜种子发芽率、苗高或根长的抑制作用最强,其次是乙酸乙酯相,其它溶剂相萃取液的抑制作用不明显。栎属种子甲醇浸提液及各有机相对白菜种子苗高和根长的抑制作用强于对发芽率的影响,说明栎属种子中所含抑制物质主要是限制自身根和芽的生长,可能是造成延迟萌发和出苗不整齐的原因。