成熟时间和干贮藏对两种木蓼种子萌发的影响

刺木蓼(Atraphaxis spinosa)和长枝木蓼(A.virgata)为蓼科木蓼属灌木,刺木蓼1a结果2次,分别于6月份和9月份成熟,而长枝木蓼果期较长,于10—11月份成熟。对2种木蓼不同成熟时间及干贮藏后的种子,进行萌发实验,结果表明:不同成熟时间的刺木蓼种子在30℃/20℃的萌发率高,长枝木蓼10月份成熟的种子在15℃/6℃的萌发率低,而11月份成熟的种子在15℃/6℃的萌发率最高。成熟早的刺木蓼种子较小,而长枝木蓼成熟晚的种子较小,不同成熟时间的2种木蓼种子均表现为,小种子的休眠程度低。刺木蓼不同成熟时间的种子在干贮藏的过程中,种子的萌发率先降低后增加。干贮藏明显提高了长枝木蓼种子在15℃/6℃的萌发率,尤其是10月份成熟的种子,10月份和11月份成熟的种子分别贮藏9个月和6个月后解除休眠。     

初生休眠解除状态和干燥处理对水曲柳种子萌发的影响

为探究初生休眠解除状态和干燥处理对水曲柳种子萌发的影响，本文以初生休眠的成熟水曲柳种子为材料，研究经不同裸层积（暖温10周+低温8周、暖温12周+低温8周、暖温10周+低温10周、暖温12周+低温10周）和干燥处理（干燥、不干燥）的水曲柳种子在适宜温度和较高温条件下的萌发表现。结果表明，初生休眠解除状态不同的水曲柳种子在不同温度下的萌发表现具有相似的规律，种子的萌发会受到干燥处理的影响。不经干燥处理的种子解除休眠越充分，其萌发能力就越强，但层积处理后的种子若经过干燥处理，则解除休眠越充分（尤其是低温时间越长），种子萌发能力下降越多。水曲柳种子次生休眠（热休眠）的诱导受种子初生休眠解除状态的影响较小，但受干燥处理影响较大。干燥处理会降低水曲柳种子的萌发能力，尤其是较高温条件下的萌发能力，初生休眠解除越充分的种子萌发受干燥处理影响越大。生产中如需对解除休眠的种子干燥处理，选择暖温10周+低温8周的层积方法处理种子效果最好。     

獐牙菜种子萌发的研究

对温度、光照、植物激素（GA₃、NAA）条件对獐牙菜（Swertia bimaculata）种子萌发的影响进行了研究。结果表明,獐牙菜种子萌发的适宜温度为15～20℃,低温贮藏可促进其萌发,而有无光照对獐牙菜种子萌发没有明显影响,GA₃处理可提高其萌发势和萌发率,而NAA处理仅提高其萌发势。研究认为：獐牙菜种子具有休眠现象;激素及低温贮藏对打破种子的休眠具有重要作用。     

中国蓼属春蓼组植物果实形态及果皮微形态的研究

应用解剖镜和扫描电镜对中国产蓼属春蓼组（Polygonum sect. Persicaria）19种3变种植物的果实形态和果皮微形态特征进行了观察和研究。结果表明,蓼属春蓼组植物的果实形态为卵形或椭圆状卵形,具三棱、双凹或双凸,顶端渐狭,有喙或无喙;果皮微形态可分为7种类型： 洼点、浅洼点,脑纹状纹饰,拟脑纹状纹饰,网状纹饰,不规则褶皱,不规则小疣状颗粒以及密浅网状纹饰。观察结果支持将绵毛酸模叶蓼（P. lapathifolium L. var. salicifolium Sibth.）合并到酸模叶蓼（P. lapathifolium L.）,做为酸模叶蓼的异名处理;支持将长鬃蓼（P. longisetum De Br.）作为丛枝蓼（P. posumbu Buch. Ham. ex D.Don）的变种处理的意见;认为密毛酸模叶蓼（P. lapathifolium L. var. lanatum (Roxb.) Stew.）应恢复种级,圆基长鬃蓼（P. longisetum De Br. var. rotunatum A.J.Li）应升为种级;支持平武蓼（Polygonum pingwuense F. Z. Li et Y. T. Hou et S. J. Fan, sp. nov.）新种的成立。     

中国蓼属植物二新种

报道了中国蓼属两新种。蜀蓼（Polygonum shuense）与大理蓼（P.subscapsum）相似,但基生叶的基部渐狭,沿叶柄下延,边缘具圆齿,花白色,花柱3,离生,瘦果长卵形,无光泽可以区别。察隅蓼（P.chayuum）产西藏,这个新种的茎不分枝,自基部至中部无叶,仅有托叶鞘,叶着生于茎的上部,这些特征奇特,明显不同于其它种类。     

中国蓼属分叉蓼组和冰岛蓼属植物叶下表皮微形态研究

采用光学显微镜对中国蓼属分叉蓼组(Polygonum section Aconogonon)和冰岛蓼属(Koenigia)的21种植物的叶下表皮微形态进行了观察研究。结果表明,其叶下表皮微形态特征可分为三种类型：（1）气孔器类型为无规则型,表皮细胞多边形,垂周壁为波状;（2）气孔器类型为无规则型兼有非典型不等型,表皮细胞为多边形或不规则形,垂周壁为平直弓形或波状;（3）气孔器类型为不等细胞型,表皮细胞多边形,垂周壁为平直弓形。分叉蓼组（西伯利亚蓼除外）植物的叶表皮气孔器类型具有高度一致性,说明该组是一个自然类群。本文研究结果不支持将大铜钱叶蓼(Polygonum forrestii Diels)、铜钱叶蓼(P. nummularifolium Meissner)划归于冰岛蓼属的处理意见;支持将西伯利亚蓼(P. sibiricum Laxm.)独立成属,即西伯利亚蓼属(Knorringia Tzvel.)的观点;同时也支持仍将多穗蓼(P. polystachyum Wall.ex Meissner)和松林蓼(P. pinetorum Hemsl.)归在分叉蓼组的处理意见。     

影响琼花种子休眠的因素

琼花种皮有吸水性,休眠非因种皮的不透水性造成.种仁中存在导致休眠的抑制物质,胚的抑制物质含量最高.种子须先经4℃低温层积60 d,再经25℃暖温处理90 d,而后在较低温(15℃)条件下才能解除休眠而萌发.当年成熟种胚在翌年10月才能彻底破除休眠.6-BA和GA对种胚破眠均无明显作用.     

温度对经层积处理解除休眠的水曲柳种子萌发的影响

经层积处理解除休眠的水曲柳种子于10种不同温度条件下萌发的结果表明:变温条件下的种子萌发比恒温条件的好,最佳的变温条件为15℃/10℃,最佳的恒温条件是10℃,20℃以上的恒温会诱导种子产生二次休眠。     

中国木蓼属的研究兼论木蓼族的系统

我国木蓼属有11种,3变种,其中特有种3个。本文通过对它们的形态,花粉等性状的研究,探 讨了属的系统位置,提出了木蓼族的演化系统。在分析了木蓼属的性状后,认为木蓼组Sect Tragopyrum(Bieb．)Meisn．较为原始,应置于刺木蓼组Sect．Atraphaxis之前。本文还研究了该属的地理分布,初步探讨了它的起源及现代分布格局的形成。     

不同发育时期水曲柳种子的形态生理变化及其层积处理后的萌发效应

探讨不同发育时期水曲柳种子的外部形态和生理变化及其层积处理后的萌发效应结果表明：水曲柳开花120d后为成熟脱水阶段,开花110d后种子的胚长和胚乳干重趋于稳定,花后110～120d期间种子胚干重趋于稳定;花后70～100d采集的种子不耐层积,层积处理后逐渐死亡,花后110d采集的种子经层积处理后可以萌发;110d后采集的水曲柳种子经暖温（20℃）16周＋低温（5℃）12周的层积处理后,其休眠破除的效果较好,适当延长暖温层积时间有利于提高种子萌发率。     

Seed dormancy-breaking and germination requirements ofDrosera anglica,an insectivorous species of the Northern Hemisphere

Seeds of Drosera anglica collected in Sweden were dormant at maturity in late summer, and dormancy break occurred during cold stratification. Stratified seeds required light for germination, but light had to be given after temperatures were high enough to be favorable for germination. Seeds stratified in darkness at 5/1 °C and incubated in light at 12/12 h daily temperature regimes of 15/6, 20/10 and 25/15 °C germinated slower and to a significantly lower percentage at each temperature regime than those stratified in light and incubated in light. Length of the stratification period required before seeds would germinate to high percentages depended on (1) whether seeds were in light or in darkness during stratification and during the subsequent incubation period, and (2) the temperature regime during incubation. Seeds collected in 1999 germinated to 4, 24 and 92 % in light at 15/6, 20/10 and 25/15 °C, respectively, after 2 weeks of stratification in light. Seeds stratified in light for 18 weeks and incubated in light at 15/6, 20/10 and 25/15 °C germinated to 87, 95 and 100 %, respectively, while those stratified in darkness for 18 weeks and incubated in light germinated to 6, 82 and 91 %, respectively. Seeds collected from the same site in 1998 and 1999, stratified in light at 5/1 °C and incubated in light at 15/6 °C germinated to 22 and 87 %, respectively, indicating year-to-year variation in degree of dormancy. As dormancy break occurred, the minimum temperature for germination decreased. Thus, seed dormancy is broken in nature by cold stratification during winter, and by spring, seeds are capable of germinating at low habitat temperatures, if they are exposed to light.     

青阳参种子的萌发

青阳参（Cynanchum otophyllum）种子在11月成熟时有休眠习性。收获后将其种子种植在自然温室内,到第二年的春天种子才会萌发,且大多数种子在3月28至4月4日间萌发,这期间的日平均最高和最低温度分别为19．0℃和9．9℃。层积能有效地打破青阳参种子的休眠,休眠种子通过大约1周的层积便能萌发。种子在有光的条件下层积1周后转移到25／15℃的黑暗条件下萌发率可达到75．4％。青阳参种子不论在有光的条件下还是在黑暗环境中层积2～3周后转入30／20和25／15℃进行变温处理,其萌发率最低能达到66．4％,而转入20／10℃变温处理其萌发率最多只能达到20．1％,但若层积6周,即便在20／10℃变温处理的情况下其萌发率也可以达到65．3％以上。     

Seed maturation time influences the germination requirements of perennial grasses in desert climate of Arabian Gulf

Qatar has a dry, subtropical desert climate, with minimum annual rainfall and intensely hot and humid summers. Using indigenous grass, those adapted to local conditions have the potential to be used for fodder and can also be used for restoration or rehabilitation of degraded rangelands. Chloris virgata, Coelachyrum brevifolium and Cenchrus ciliaris bloom twice a year from April to May (summer) and September to October (winter) under the nursery condition. Therefore, it is important to understand, how seeds produced in different seasons affect the dormancy as well as germination of these species. Seeds of C. virgata, C. brevifolium and C. ciliaris, three desert grasses, were collected from the plants growing on Shahniya nursery in two different seasons, summer (May) and winter (October). The seeds collected in May (summer) were stored up to winter. However seeds collected in October (winter) were immediately used for experiment. We compared the germination potential of seeds that matured in different season at different alternating temperatures at 15/25, 20/30 and 25/35 °C. Lower temperatures correspond to the dark period, while higher temperatures reflect the light period. Seeds collected in summer season (old seeds) were heavier as compared to seeds collected in winter season (new seeds). Winter seeds of C. virgata seem to be dormant, while summer seeds, germinated well in all the tested temperature regimes. However, C. ciliaris seeds showed opposite trends.     

Morphophysiological dormancy in seeds of the ANA grade angiosperm Schisandra arisanensis (Schisandraceae)

We determined the kind of seed dormancy in Schisandra arisanensis, an ANA grade ([A]mborellales [N]ymphaeales [A]ustrobaileyales) angiosperm with medicinal value. Seeds have small underdeveloped embryos, and following seed maturity their length increased approximately 360% before radicle emergence. Germination was delayed 6–8 weeks, and the percentage and rate were much higher at 15/6, 20/10 and 25/15°C than at 30/20°C. For seeds incubated at 5/5°C (8 weeks) → 15/6°C (4 weeks) → 20/10°C (8 weeks) → 25/15°C (12 weeks) → 20/10°C (5 weeks), embryos grew at 15/6°C → 20/10°C, and almost all seeds that germinated (89%) did so at 20/10°C → 25/15°C. When seeds were incubated in a complementary temperature sequence, 25/15°C (12 weeks) → 20/10°C (8 weeks) → 15/6°C (4 weeks) → 5/5°C (9 weeks) → 15/6°C (4 weeks), embryos grew at 25/15°C → 20/10°C. Nearly all seeds that germinated (93%) did so at 25/15°C → 20/10°C and at 15/6°C following 9 weeks at 5/5°C. Based on the temperature requirements for embryo growth and seed germination, seeds of this species have non‐deep simple morphophysiological dormancy (C_1bB).     

陕北黄土丘陵沟壑区14种植物的萌发特性

在实验室条件下观测了陕北黄土丘陵沟壑区14种植物的萌发特性,结果发现：萌发率在80%以上的植物有杠柳、铁杆蒿和茭蒿;在60%～80%之间的物种有白羊草、紫丁香、阿尔泰狗娃花、大针茅、沙棘和猪毛蒿;长芒草为37.3%;小于20%的植物有达乌里胡枝子、刺槐、虎榛子和狼牙刺。14种植物的萌发时滞最短的为2 d,最长的为8 d;几乎所有植物种子达到T50的时间都在其萌发开始后的7 d以内,且大部分物种在萌发开始后的15 d完成总萌发量的90%;萌发持续时间最短的为6 d,有刺槐、狼牙刺、虎榛子、沙棘4种,最长的为猪毛蒿,达32 d。这些植物种子的萌发特性及生态适宜性决定了它们在陕北黄土丘陵沟壑区植被演替中的角色与地位。     

Seed germination of Lasia spinosa as a function of temperature,light, desiccation,and storage

Lasia spinosa seeds were not dormant at maturity in early spring. The most favorable temperatures for germination were between 25 and 30 °C, and final percentage and rate of germination decreased with an increase or decrease in temperature. When L. spinosa seeds were transferred to 25 °C, after 60 days at 10 °C (where none of the seeds germinated), final germination increased from 0% to 78%. Seeds germinated to high percentage both in light and in dark, although dark germination took more than twice as long as in the light. During desiccation of seeds at 15 °C and 45% relatively humidity, moisture loss decreased exponentially from 2.02 to 0.13 g H₂O g⁻¹ dry wt within 16 days, and only a few seeds (12%) survived 0.13 g H₂O g⁻¹ dry wt moisture content. Seeds stored at 0.58 g H₂O g⁻¹ dry wt moisture content at four constant temperatures (4, 10, 15, and −18 °C) for up to 6 months exhibited a well-defined trend of decreasing viability with decreasing temperature. Thus, we concluded that freshly harvested L. spinosa seeds are non-dormant and recalcitrant. Also, the seeds with 0.58 g H₂O g⁻¹ dry wt moisture content could be effectively stored for a few months between 10 and 15 °C although the most appropriate temperature for wet storage appears to be 10 °C, as it is close to the minimum temperature for germination and so there will be less pre-sprouting compared to 15 °C.     

Seed germination and dormancy in the medicinal woodland herbs Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae)

We used a double germination phenology or “move-along” experiment (sensu Baskin and Baskin, 2003) to characterize seed dormancy in two medicinal woodland herbs, Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae). Imbibed seeds of both species were moved through the following two sequences of simulated thermoperiods: (a) 30/15 °C→20/10 °C→15/6 °C→5 °C→15/6 °C→20/10 °C→30/15 °C, and (b) 5 °C→15/6 °C→20/10 °C→30/15 °C→20/10 °C→15/6 °C→5 °C. In each sequence, seeds of both species germinated to high rates (>85%) at cool temperatures (15/6 and 20/10 °C) only if seeds were previously exposed to cold temperatures (5 °C). Seeds kept at four control thermoperiods (5, 15/6, 20/10, 30/15 °C) for 30 d showed little or no germination. Seeds of both species, therefore, have physiological dormancy that is broken by 12 weeks of cold (5 °C) stratification. Morphological studies indicated that embryos of C. canadensis have “investing” embryos at maturity (morphological dormancy absent), whereas embryos of D. villosa are undeveloped at maturity (morphological dormancy present). Because warm temperatures are required for embryo growth and cold stratification breaks physiological dormancy, D. villosa seeds have non-deep simple morphophysiological dormancy (MPD). Neither species afterripened in a 6-month dry storage treatment. Cold stratification treatments of 4 and 8 weeks alleviated dormancy in both species but C. canadensis seeds germinated at slower speeds and lower rates compared to seeds given 12 weeks of cold stratification. In their natural habitat, both species disperse seeds in mid- to late autumn and germinate in the spring after cold winter temperatures alleviate endogenous dormancy.     

Seed germination in Marathrum schiedeanum and M. rubrum (Podostemaceae)

Marathrum schiedeanum and Marathrum rubrum are annual Podostemaceae, thus their seeds are important to their dispersal and persistence in their habitat. We assessed the effect on germination of (1) light (white, red and far red) and darkness, (2) temperature (15, 20, 25, 30 °C and alternating 20/30 °C), (3) osmotic potential (0 to −0.8 MPa), (4) proximity to moisture sources and (5) seed storage. Seeds of M. schiedeanum and M. rubrum were non-dormant and had a high germination capacity (96%). Seeds were positive photoblastic; at 15 °C germination drop to zero, and germination rate was slower at 20 °C and at 20/30 °C than at 25 °C. A small proportion of seeds of both species germinated even at osmotic potentials as low as −0.6 MPa (11%) for M. rubrum and −0.8 MPa (70%) for M. schiedeanum. Seeds germinated only when near to the source of moisture (91.3–87.1% and 53.3–35.6% for M. schiedeanum and M. rubrum, respectively) and 2 years in dry storage did not modify their capacity to germinate. At the beginning of the rainy season, light and temperature in the rivers may be high enough for germination. The ability to germinate at low osmotic potential may be related to early germination during the rainy season. This may be because the seed mucilage assists in diffusion of water from the substrate to the seed. Both species germinated faster at −0.06 MPa, than in distilled water, which may indicate appropriate conditions for germination of these short-lived species.     

Seed germination ecology of the annual grass Leptochloa panicea ssp. mucronata and a comparison with L. panicoides and L. fusca

Leptochloa panicea ssp. mucronata is an annual grass that grows in relatively dry habitats. Requirements for dormancy loss and germination were determined for seeds of this species and compared to those of two species from wet habitats. Seeds of L. panicea were dormant at maturity in autumn, but when exposed to actual or simulated autumn temperatures (e.g. 20/10, 15/6 °C), they entered conditional dormancy and thus germinated to high percentages in light at 35/20 °C. Seeds buried in non-flooded soil exposed to natural seasonal temperature changes in Kentucky (USA) were non-dormant by the following summer and germinated to 80–100 % in light at 25/15, 30/15 and 35/20 °C. Seeds buried in non-flooded soil exhibited an annual conditional dormancy/non-dormancy cycle, with seeds mostly germinating to 80–100 % in light at 30/15 and 35/20 °C throughout the year but to 80–100 % in light at 25/15 °C only in summer. Results for L. panicea were compared to published data for L. panicoides and L. fusca. Whereas seeds of L. panicea buried in flooded soil failed to come out of dormancy, those of L. panicoides, an annual of moist habitats such as mudflats, exhibited an annual conditional dormancy/non-dormancy cycle, and those of L. fusca, a semi-aquatic, required flooding for both dormancy loss and germination. Differences in dormancy breaking and germination responses of seeds of Leptochloa species may help to explain why this genus occupies a wide range of habitats with regard to soil moisture conditions.