极度濒危植物大果木莲种子的休眠与萌发

大果木莲种子具吸水性,胚未完全发育。新鲜种子25℃下的萌发率仅2％,在30／20℃和20／10℃的条件下30d内分别有27％和36％种子萌发。在20／10℃下,1000mg·L^-1浓度的GA3可以有效打破种子休眠。冷层积120d的种胚生长不显著,大果木莲种子具有条件休眠特性,属于浅度简单型形态生理休眠。种子经冷层积60d的萌发率最高,而后下降,提示其可能有休眠循环现象。     

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。     

杭州石荠苎种子萌发的生理生态学研究

本文研究了我国特有的、分布区极狭窄的１年生草本植物－杭州石荠苎种子萌发的生理生态学特性。结果表明：杭州石荠苎种子冬天休眠,早春开始萌发;萌发的温度范围是１０￣３５℃,２０℃时萌发率最高,因此其萌发的季节仅限于春季;变温处理的萌发率不高于恒温处理;全日照和黑暗条件使萌发率比最适条件的萌发率降低３６％;水选上层种子的萌发率仅为７％,水选下层种子萌发率可达６０％,但水选下层种子在全部种子中仅占３２．６％     

光照和温度对沙芥和斧翅沙芥植物种子萌发的影响

研究了生长于不同生境下的沙芥(Pugionium cornutum(L.)Gaertn.)和斧翅沙芥(Pugionium dolabratum Maxim.)种子萌发对光照和温度的响应。结果表明:沙芥和斧翅沙芥种子在光下萌发受到显著(P0.05)的抑制作用,其中沙芥种子萌发受光的抑制作用强于斧翅沙芥种子。在黑暗10—40℃恒温条件下,沙芥和斧翅沙芥种子在15—35℃范围内均可萌发,在15℃和35℃下沙芥种子的萌发要优于斧翅沙芥种子;其种子分别在25℃和30℃下达到最佳的萌发响应,在此条件下斧翅沙芥种子的萌发特性优于沙芥种子。在黑暗变温条件下,沙芥和斧翅沙芥种子在20/30℃(12h/12h)下达到最佳的萌发响应,此处理下的萌发率高于其各自最佳恒温处理下的萌发率,其萌发后幼苗下胚轴和胚根的长度较最佳恒温处理有明显的下降,但它们的干重却差异较小,说明变温处理有利于两种种子的萌发和形成强壮的幼苗。综上所述,沙芥和斧翅沙芥种子在黑暗和20/30℃变温条件下有利于种子萌发和幼苗建成。     

毛叶山桐子种子休眠与萌发特性的研究

目的：探究毛叶山桐子种子(Idesia polycarpa Maxim. var. vestita Diels)的休眠类型和解除休眠的最适方法，为生产实践中的种苗繁育提供一种能有效解除毛叶山桐子种子休眠和提高萌发率的方法。方法：以成熟的毛叶山桐子种子为材料，研究种子的水分透性及温度、光照、去垢剂、后熟、层积和植物激素对种子休眠与萌发的影响。结果：(1)种子具有发育成熟的胚，种皮被有蜡质层但具有透水性；(2)在10～35℃和交替光照(12 h光照/12 h黑暗，光强度为144μmol·m^-2·s^-1)下萌发30 d，种子的萌发率低于30%，具有休眠特性；(3)种子在完全黑暗条件下几乎不萌发，是一种需光性种子；(4)4℃和10℃层积30 d显著地增加种子的萌发速率和萌发率，后熟90 d则对种子萌发没有影响；(5)GA3能部分解除种子的休眠和促进萌发，将萌发率提高至56.7%，氟啶酮则没有作用。结论：毛叶山桐子种子的休眠类型为非深度生理休眠，解除休眠和促进萌发的最适方法是将种子在4℃或者10℃中层积30 d，然后在25℃和交替光照中萌发。     

刺木蓼和长枝木蓼种子休眠的解除及萌发条件

刺木蓼（Atraphaxis spinosa）和长枝木蓼（A.virgata）为蓼科木蓼属灌木,是乌鲁木齐周边植被组成的重要种。这两种木蓼种子成熟后不萌发,处于休眠状态,对其种子进行5℃（黑暗）和野外低温层积处理,结果表明：5℃层积处理能明显提高两种木蓼种子在15/6、20/10、25/15和30/20℃（昼12 h/夜12 h）的萌发率。野外层积处理显著提高了种子在15/6℃的萌发率。刺木蓼和长枝木蓼的种子均为非深度生理休眠,分别经8、6周的低温层积处理后种子休眠得以解除。刺木蓼种子的休眠程度比长枝木蓼深,休眠解除后,种子萌发所需的最低温度降低。这两种木蓼种子经过冬天的低温层积,可以在春天较低的生境温度下萌发。     

狼毒种子萌发特性与种群更新机制的研究

研究了采集于植株上的和收集于土壤种子库的狼毒(Stellera chamaejasme)种子在不同温度、光照和5种预处理(即破裂种皮、去除种皮、98％H2SO4浸种5min、0．2％KNO3浸种24h、10℃低温保存1周)条件下的萌发力。结果表明,狼毒种子萌发率较低,25℃恒温、黑暗条件下萌发率为13％,较适宜的萌发温度为30℃恒温或10～30℃变温,破裂种皮和去除种皮萌发率显著提高,25℃恒温、光暗交替条件下萌发率分别为49％和47％,浓硫酸浸种5min处理萌发率可达到32％,KON3浸种和10℃低温保存两个处理对促进狼毒种子萌发效果不明显,狼毒种子萌发对光照条件不敏感,种子硬实性是导致狼毒种子萌发率较低的主要原因,取自土壤种子库内的狼毒种子萌发率高于当年采集的种子,在自然条件下,并非每年都有狼毒种子萌发长成幼苗,种群更新时机是随机的或周期性的。     

丛毛垂叶榕种子萌发的光敏感性及其生态意义

以丛毛垂叶榕（Ficns benjamina L．var．nuda）种子为实验材料,研究了温度、光照、植物激素（GA3、6-BA、乙烯）和含氮化合物（硝普钠、亚硝酸盐和硝酸盐）对种子萌发的影响,讨论了光在丛毛垂叶榕种子萌发中的生态意义。在交替光照下（14h光照,10h黑暗,12μmol m^-2s^-1）,种子在15℃、20℃、25℃、30℃、35℃、40℃和30℃,20℃下的最终萌发率分别为87．5％、100％、100％、100％、98％、89％和100％;种子的平均萌发时间分别为34．7d、16．3d、5．6d、4．8d、6．4d、9d和6．3d。黑暗条件下,种子在15℃、20℃、25℃、30℃、35℃、40℃和30℃／20℃下萌发35d,种子的萌发率为零;添加交替光照后,种子迅速萌发。0．5～20μmol m^-2s^-1的光照强度显著地增加种子的最终萌发率,不同的光照强度对种子的最终萌发率没有明显的影响,但影响种子的萌发速率。在24h光暗周期下,种子的最终萌发率随着光期长度的增加而显著提高。在连续光照下处理24h、36h和48h后能够促进种子在随后的连续黑暗中萌发。不同浓度的GA3、6-BA、乙烯、硝普钠、NaNO3和NaNO2处理不能代替光照在黑暗条件下促进种子萌发,添加交替光照后,种子迅速获得萌发能力。丛毛垂叶榕种子的上述萌发行为与其长期适应热带雨林的生境密切相关。     

箭叶淫羊藿种子的休眠类型与萌发研究

箭叶淫羊藿具有重要的药用价值和较大的市场需求,但其种子休眠和萌发特性目前仍不够清楚,严重影响了其产业化育苗与栽培。为探明其种子的休眠类型及释放休眠和促进休眠的最适方法,该文以箭叶淫羊藿的成熟种子为材料,研究种子对水分的吸收、种子的脱水耐性,以及温度、层积和植物激素对种子休眠与萌发的影响。结果表明:(1)箭叶淫羊藿种子不具有物理休眠,而具耐脱水性。(2)在4～25 ℃和黑暗条件下,种子萌发率为零,具有休眠特性。(3)胚与种子的比值非常小,4 ℃和10 ℃及变温层积能显著地促进胚的生长发育以及增加种子的萌发速率和萌发率。(4)赤霉素和氟啶酮显著增加种子的萌发速率和萌发率。综上认为,箭叶淫羊藿种子的休眠类型为形态生理休眠(MPD),释放休眠和促进萌发的最适方法是先将种子在10 ℃中层积30 d,再置于4 ℃环境中让其萌发。该研究结果为箭叶淫羊藿的产业化育苗提供了参考。     

中国特有植物凹叶木兰种子的休眠与贮藏行为

凹叶木（Magnoliasargentiana）是中国特有的观赏树木,种群的自然更新很差,须阐明其原因。研究发现,凹叶木兰种子的胚很小,无论是否被植物生长调节剂预处理,在冷层积（4℃）和暖层积（15℃）过程中,胚在种子内逐渐生长发育成熟,并能在多个温度下萌发,以变温30℃／20℃为最适宜。由此可见,凹叶木兰种子不能萌发的直接原因是形态休眠。此外,凹叶木兰种子较耐脱水,但干燥脱水至含水量为7．1％和5．3％时,种子的存活率分别是78．3％和40％。保存6个月后,含水量为9．4％或7．1％的种子在-20℃下全部失活,而在0和4℃下的种子,存活率无显著变化,充分证实凹叶木兰种子是中间性的。     

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.     

Germination responses of Discopodium penninervium Hochst. to temperature and light

The germination responses of Discopodium penninervium were tested at different constant and alternating temperature regimes as well as under various light conditions both in the laboratory and glasshouse. Seeds incubated at 10, 15, 20, 25 and 30 °C failed to germinate. When the seeds were incubated at alternating temperatures of 20/12 °C and 30/12 °C under continuous light, germination was 89 and 61%, indicating that the species requires alternating temperatures as a cue for germination. However, germination declined as the amplitude of alternating temperatures increased from 8 °C and was completely inhibited at an amplitude of 23 °C, suggesting that the optimum amplitude is around 8 °C. Germination was less than 10% in light and nil in darkness at 20 °C in the laboratory. In contrast, seeds incubated at 20/12 °C germinated to 96 and 86% in light and darkness, respectively. Seeds incubated under leaf shade in the glasshouse failed to germinate whereas those incubated under direct daylight and darkness germinated to 44 and 50%, respectively, 30 days after sowing. When seeds incubated under leaf shade and in darkness were exposed afterwards to light, final percent germination was 83% from seeds incubated initially under direct daylight, 79% from those incubated under leaf shade and 86% from those incubated in darkness. The requirement for alternating temperatures and light rich in red:far red ratio to break the dormancy of seeds of D. penninervium could restrict germination to gaps in the vegetation. The results conform with the ecology of the species.     

Ethylene as a possible cue for seed germination of Schoenoplectus hallii (Cyperaceae), a rare summer annual of occasionally flooded sites

The purpose of our research was to determine why seeds of Schoenoplectus hallii germinate only in some wet years. Seeds mature in autumn, at which time they are dormant. Seeds come out of dormancy during winter, if buried in nonflooded, moist soil, but they remain dormant if buried in flooded soil. Nondormant seeds require flooding, light, and exposure to ethylene to germinate. One piece of apple in water (1/12 of an apple in 125 mL of water in a glass jar for a depth of 5 cm) or a 1-μmol/L solution of ethephon elicited very similar (high) germination percentages and vigor of seedlings. Apple, which was shown to produce ethylene in the air space of the jar, was used in a series of experiments to better understand germination. Seeds germinated to 72% if apple was removed from the water after 1 d of incubation, and they germinated to 97% if seeds were washed and placed in fresh water after 3 d of exposure to apple. No seeds germinated in control with no apple. Seeds incubated in apple leachate for 5 d and then transferred to filter paper moistened with distilled water germinated to 90%. Minimum depth of flooding in apple leachate (no soil in jars) for optimum germination was ≥3 cm. Buried seeds of S. hallii exhibited an annual conditional dormancy/nondormancy cycle. Regardless of the month in which seeds were exhumed, they germinated to 59-100% in light in water with apple at daily alternating temperature regimes of 25°/15°, 30°/15°, and 35°/20°C, but germination at 20°/10°C (and to some extent at 15°/6°C) tended to peak in autumn to spring. Thus, seeds can germinate throughout the summer if flooded (ethylene production) and exposed to light. An ethylene cue for germination serves as a "flood-detecting" mechanism and may serve as an indirect signal that water is available for completion of the life cycle and competing species are absent.     

贵州毕节喀斯特地区优势植物种子萌发特性初步研究

对采自贵州毕节地区的11种植物的种子萌发特性进行了初步研究,结果表明：①盐肤木、火棘、化香、云贵金丝桃与白栎种子在4周之内能够萌发;除云贵鹅耳枥胚坏死之外（萌发实验前后对种子进行解剖）,其他5种植物的种子都未萌发,处于不同的休眠状态。②盐肤木、化香、云贵金丝桃的种子光照时的萌发率远高于黑暗时的萌发率,具有显著差异,尤其是云贵金丝桃,因此3种植物种子均属于喜光性种子;而火棘与白栎种子有无光照都可以萌发,而且萌发率没显著差异,因此属于光不敏感或光中性种子。③盐肤木、云贵金丝桃的种子在30℃较高温条件下萌发最好;白栎、火棘种子在15℃、20℃低温条件下萌发更好;化香种子萌发温度既不能低于20℃也不能高于25℃。④刺异叶花椒种子吸水率高达85%,胚包埋在胚乳之中非常微小、未分化,因此可以初步判定属于形态休眠或者形态生理休眠;而平枝荀子、西域旌节花、云南旌节花种子吸水率都在20%以上,胚长/种子长都超多1/2,并且胚已发育完全,应属于生理休眠;小果蔷薇种子吸水率约27%,胚长/种子长都达2/3,并且通过对种子的解剖发现胚还未发育,应属于形态生理休眠。     

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).     

EFFECT OF STRATIFICATION TEMPERATURE AND GERMINATION TEMPERATURE ON GERMINATION AND THE INDUCTION OF SECONDARY DORMANCY IN COMMON RAGWEED SEEDS

Stratification of common ragweed (Ambrosia artemisiifolia) seeds at 4 C was most successful for breaking dormancy, whereas -5 C was least effective and 10 C was intermediate. Germination in the light exceeded that in the dark at all stratification and germination temperatures. The optimum temperatures for germination in the light were 10/20, 15/25, and 20/30. Maximum germination in the dark occurred at 20/30 C for seeds stratified at 4 and 10 C but the optimum temperatures for seeds stratified at -5 C were 10/20, 15/25, and 20/30. Seeds stratified at -5 and 10 C germinated best after 15 weeks of stratification, whereas 12 weeks of stratification at 4 C resulted in maximum germination. Secondary dormancy was induced in seeds which did not germinate in the dark. This was affected by stratification temperature and duration and germination temperature. The ecological significance of these germination characteristics is discussed.     

Some effects of nitrate-treated soil upon the sensitivity of buried redroot pigweed (Amaranthus retroflexus L.) seeds to ethylene, temperature, light and carbon dioxide

Abstract Fresh dormant redroot pigweed (Amaranthus retroflexus L.) seeds were buried 5 cm deep in the field at Stoneville, MS in November 1981. Potassium nitrate (200 kg ha ¹) or nothing was applied to the soil in the fall of 1981 and the late winter of 1982. Seeds were recovered at intervals under darkness during the following 2 years and tested for responses to ethylene, temperature, light and carbon dioxide. During the first overwintering, nitrate enhanced loss of primary dormancy and increases seed sensitivity to temperature, light and ethylene. The loss of dormancy reached a maximum at 25 to 30 weeks (early summer) after burial. Examination of the recovered seeds indicated that about 80% of the non-treated seeds and 98% of the nitrate-treated seeds germinated in situ during the period of maximum loss of dormancy. Thus, after one overwintering period, about 20% of the original buried seed population remained dormant in nontreted soil and 2% remained dormant in the nitratetreated soil. After the second overwintering, the percentages of dormant seeds remaining in nontreated or treated soil were both only 1–2%. Nitrate reduced dormancy and enhanced germination in early summer following the first overwintering. Regardless of treatment, the remaining 1 2% of seeds in soil after the second year were of low sensitivity to the germination stimuli (ethylene, temperature, light) and constituted the long-lived portion of the original seed population.     

Effects of seed colour heterogeneity on germination behaviour of the desert plant Lotononis platycarpa (Fabaceae)

We aimed to determine the ecological role of three seed morphs observed for the first time in a desert population of Lotononis platycarpa (Fabaceae), with respect to their germination requirements. Seeds sorted by seed coat colour (olive green, orange and brown) were germinated under laboratory conditions under two photoperiods (12/12‐h light and continuous dark) and three alternating temperature regimes (15/25, 20/30, 25/35°C). We found that the three distinct seed types differ in their seed mass, germination percentage and speed of germination. Overall, the light‐incubated seeds germinated with higher percentages than seeds in the total darkness. Furthermore, seeds with orange coat germinated with higher percentages at 15/25 and 25/35°C (up to 60%, for both) and significantly faster than the other two colour morphs. Our results suggest an adaptive significance of seed colour heterogeneity in the harsh desert habitat inhabited by the study species.