短命植物独行菜种子萌发过程对低温的耐受特性

以独行菜（Lepidium apetalum）为材料,研究了其种子在萌发过程中耐受低温的特性,并对耐受低温的机制作了初步的探讨。结果表明：1.萌发至I、II、III期的独行菜种子经过冷诱导处理后,对零下低温-5℃、-10℃胁迫具有较强的耐受性,这种耐受性随萌发发展相对有所降低。2.独行菜种子萌发过程中胚根生长速度明显受到低温抑制,但也仍然能够生长。3.适当时间的低温层积能使独行菜萌发势显著提高,对终萌发率影响不大;过长时间的低温层积会使独行菜种子萌发势和最终萌发率降低。4.独行菜种子在4℃条件下不能萌发,但4℃层积2d的种子经25℃处理6h以上后,可耐受4℃低温而萌发,且萌发率随25℃处理时间增加而升高。如果25℃处理时间少于5h则不能在4℃低温下萌发。经4℃层积10d、再经25℃萌发处理1h的独行菜种子就能在4℃低温下萌发。综合分析认为独行菜种子不能耐受4℃低温萌发,原因可能是在露白前存在一个关键的生理阶段,在4℃胁迫逆境中不能越过这个阶段,该阶段之前与之后的萌发过程都能耐受4℃低温,因此对低温胁迫有良好的耐受性。这为探索早春短命植物耐受低温萌发的机制提供了新的思路。     

Seed Dormancy,Germination and Storage Behavior of Magnolia wilsonii (Magnoliaceae), an Endangered Plant in China

In this paper, we measured the embryo morphology and size of Magnolia wilsonii seeds. And the effects of temperature, stratification, KNO3 and soaking on seed dormancy and germination were studied. Seeds were desiccated to different moisture content, and then stored at 4℃ and -20℃ for 100 d. The effects of desiccation and storage temperature on seed viability of M. wilsonii were analyzed. The results showed that the underdeveloped embryos of Mwilsonii seeds needed cold stratification to achieve physiological afterripening. The favorable temperature for germination of Mwilsonii seeds was 25/20℃. Cold stratification and GA3 could effectively overcome dormancy of Mwilsonii seeds. Therefore, Mwilsonii seeds have morphophysiological dormancy. About 5350% of seeds could survive in the moisture content of 539%. After 100 d storage at -20℃, all seeds in different moisture contents died. However, after 100 d storage at 4℃, 76% of seeds survived. Thus, Mwilsonii seeds exhibited intermediate seed storage behavior. The optimum storage environments was dry or moist storage at 4℃.     

香圆种子萌发特征及催芽技术

以香圆（Citrus wilsonii Tanaka）种子为实验材料,通过测定种皮透水性、种皮机械障碍、发芽温度等对种子萌发的影响从而探讨种子萌发特征;通过切割种子、热水浸种、赤霉素浸种、低温层积等处理方式探索种子的催芽方法。结果显示：香圆种皮不存在透水性障碍,但其机械障碍对种子萌发具有抑制作用,且内种皮对萌发影响较大;种子在15℃、25℃、35℃恒温及15℃/30℃变温条件下均可萌发,其最适萌发温度为25℃;采用低温层积、热水浸种、切除1/3种子等方法均可一定程度上促进种子萌发。生产中宜采用始温60℃热水浸种24h的方法对香圆种子进行催芽。     

Cold stratification and growth of radicles of loblolly pine (Pinus taeda) embryos

The mechanism of germination enhancement by cold stratification was examined in seeds of loblolly pine ( Pinus taeda L. ), Removal of the seed coat permitted elongation of radicles from unstratified embryos, but both rates of germination and radicle elongation were increased by stratification. Radicles of both stratified and unstratified embryos excised from the megagamethophyte elongated only when in contact with solid incubation media supplemented with sucrose. Stratification of embryos either in the presence or absence of the megagametophyte resulted in similar enhancement of radicle elongation. Elongation rates of radicles were increased after stratification independent of sucrose concentration, and changes in sucrose content in the megagamethophyte during stratification or incubations subsequent to stratification were insufficient to regulate radicle growth. Our results support the hypothesis that the embryos of pine seeds perceive the low temperature stimulus directly and this stimulus results in a growth potential increase in the embryonic axes. We propose that this growth potential increase enables the embryos to overcome the mechanical restraint of the seeds coats and to germinate.     

The Effect of Low Temperature during Imbibition on Germination Characteristics of Tetracentron sinense (Tetracentraceae) Seeds

In this paper, the effects of low temperature, soil moisture and freezing time on the germination of Tetracentron sinense Oliv. seeds were studied by simulating wild environment conditions, and the factors influencing the natural regeneration of Tsinense population were discussed. The results are as follows: (1) The imbibition process of Tsinense seed can be divided into four stages, the water absorbing capacity of Tsinense seed after imbibition would increase with the increase of soil moisture, and the seeds would be fully imbibed under the condition of 30% soil moisture; (2) The germination rate, germination force and water content of Tsinense seed increased with the increase of storage time, and the vigor index gradually decreased after increasing before; (3) At different low temperature, the germination rate of Tsinense seed reached the highest when the soil moisture is 20% or 30%; (4) When treated at 20% soil moisture for 2-4 days or 21-28 days, 0℃ is best for the germination rate of Tsinense seed; when treated at 30% soil moisture for 14-28 days, -7℃ is best fort he germination rate of Tsinense seed; (5) When treated at the same condition of freezing time, the germination rate of seeds in fallen leaves had no significant difference with the decrease of low temperature; under the same condition of low temperature (0℃ low temperature except), the germination rate increased after frozen 28 days. The results showed that there is no significant influence of low temperature during imbibition on germination characteristics of Tetracentron sinense seeds and indicating that low temperature during imbibition is not the main factor influencing the natural regeneration of Tsinense population.     

濒危植物西康玉兰种子休眠、萌发及贮藏特性

研究了西康玉兰(Magnolia wilsonii)种胚的形态大小,温度、层积、硝酸钾、浸种处理和GA_3对种子休眠及萌发的影响.通过将种子脱水至不同含水量和在两种温度(4℃和一20℃)下贮藏100 d后测其生活力,分析各处理对西康玉兰种子活力的影响.结果表明:西康玉兰种子胚尚未分化完全,需经过低温层积完成生理后熟;低温层积和GA3可打破种子休眠.种子最适萌发温度为25/20℃.由此推测,西康玉兰种子具有形态生理休眠特性.西康玉兰种子当含水量降至5.39%,存活率为53.50%.不同含水量的种子贮藏在-20℃条件下,100 d后种子全部死亡;但在4℃下含水量为10.31%的种子存活力高达76%.因此,西康玉兰种子极可能属于中间性种子,其适宜贮藏环境为4℃下的干藏或湿藏.     

蛋白酶抑制剂对含水生菜种子耐冻性的影响

选取生菜(Lactuca sativa)种子作为试材,外源添加蛋白酶抑制剂2-硝基苯甲酸[5,5'-Dithiobis-(2-nitrobenzoic acid),DTNB]对种子吸胀处理,通过程序降温,分析2-硝基苯甲酸对低温下种子发芽率及生理活性的影响。结果表明,低温下含水生菜种子的致死温度为–20 ℃;外源添加2-硝基苯甲酸2 mmol·L–1时种子发芽率最高,即对种子活性的保护效果显著;在此浓度下种子内SOD活性比对照提高1.38倍,羟基自由基清除能力提高1.17倍;与对照组相比产生两种新的蛋白11 S种子贮藏球蛋白Jug r4和11 S种子贮藏球蛋白2,均属于球蛋白家族,可提高含水种子的耐冻性;低温下种子内积累更小分子量的球蛋白多肽,对种子具有低温保护效果。综上,低温条件下生菜种子产生一定的抗冷反应,外源添加2 mmol·L–1 2-硝基苯甲酸可提高含水种子发芽率及生理活性,产生抗冻蛋白,积累更小分子量的球蛋白多肽进而提高种子抗冻性。     

Relevant Effects of Ethylene and Ga2+ on Germination of Lettuce Seeds

Relevant effects of ethylene and Ca2+ on germination of lettuce (lactuce sative L.) seeds were investigated. It was shown previously that lettuce seeds were highly sensitive ro temperatures. More than 70% of seeds germinated at 22℃, but they ceased to germinate at 25℃. 40%–50% of seeds could be induced to germinate after imbibition with 400 ppm exogenous ethylene for 3 days at 25℃. The amounts of endogenous ethylene liberated at 22℃ were much greater than those at 25℃. Ethyleneglycol bis NN tetraacetic acid(EGTA, Ca2+ specified chelating regent) La3+, Co2+ and chlorpromazin(CPZ, calmodulin antagonist) could be used ant only to inhibit germination at 22℃, but also to inhibit germination induced by ethylene at 25℃. Although La3+ and CPZ inhibited seed germination, they could not repress the production of ethylene at 22℃. It was suggested that Ca2+ and CaM affected the induction response of ethylene to lettuce seed germination, but had no effect on ethylene liberation. Co2+ could be applied to inhibit the action as well as its production of ethylene.     

光照和温度对滇丁香种子萌发的影响

研究了不同光照和温度条件对滇丁香(Luculia pinciana)种子萌发的影响。结果表明,滇丁香种子是需光种子,有明显的光休眠现象;种子在光下萌发的最适温度范围为20~25℃,8~10d开始萌发,2~3周萌发完全,萌发率可达97%,温度的升高或降低均会降低种子萌发率。在15~30℃,用250mg/L GA₃处理24h能代替光照解除光休眠。     

野生秀丽四照花种子生物学特性及萌发研究

对野生秀丽四照花(Cornus hongkongensis subsp. elegans)种子的生物学特性进行观察测定,比较变温、低温层积、化学处理对种子萌发的影响。结果表明,秀丽四照花种子千粒重76.91 g,长5.81 mm、宽5.10 mm、厚3.99 mm。种子在整个试验过程中吸水率低于8%,说明有吸水性障碍的坚硬种皮抑制了种子萌发。变温条件下,温差较大的30℃/15℃处理对秀丽四照花种子萌发有较好的促进作用,萌发时滞短,萌发率和发芽势较高。秀丽四照花种子经30%NaOH浸泡10 min,可明显缩短萌发时间,但4℃低温层积处理对种子萌发没有显著效果。     

萝卜种子萌发的逆温耐性诱导研究

以萝卜种子为试材,研究不同温度预处理对萌发期萝卜种子逆温耐性的影响。结果表明:萝卜种子在低于15℃和高于35℃下萌发,种子活力显著下降,而通过适度的温度胁迫处理,可提高萝卜种子在高温（35℃）下的萌发活力。15℃和25℃分别是预处理的适宜低温和高温,6 h是低温（15℃）预处理的适宜时间。萝卜种子经高温（30℃）预处理12 h后,在随后的低温（10℃）下萌发,也提高其种子活力,说明萝卜种子对高温和低温胁迫具有交叉适应性。     

Preliminary Study on Development,Germination and Desiccation Tolerance of Jatropha curcas (Euphorbiaceae)

The developmental changes in morphology and germinability of Jatropha curcas seeds, effects of temperature and light on seed germination , and changes in desiccation tolerance of mature seeds were studied in this paper. The results indicated that J. curcas seeds reached a physiological maturation at 58 days after anthesis, and that seed germination percentage reached a peak at physiological maturation, and then decreased. The optimal germination temperature was 25 to 30℃. J. curcas seeds were insensitive to dehydration at physiological maturation . There was not a notable effect of light on seed germination. Therefore, J. curcas seed was a non-photoblastic and orthodox seeds .     

Biological Characteristics of Seeds of Endangered Plant Tetracentron sinense （Tetracentraceae）

By detecting the indicators of seeds such as the morphology and physiological characteristics within three consecutive years, the effects of different storage temperatures and time, and different media on seed germination of Tetracentron sinense were discussed, and also the endangered mechanism associated with biological characteristics of seeds was analyzed. The seeds of T.sinense were very small. No significant difference existed associated with seed morphology, 1000 seed weight, water content and plumpness, except for water absorption rate among seeds from different year, and the water absorption rate of seeds from 2007 was the fastest. The TTC results showed that the percentage of seed vigor was close to zero, but the vigor index of seeds among different year was respectively 0, 041 and 027, which indicated that TTC was not suitable for the estimation of Tsinense seed vigor. After stored at lower temperature, the germination rate of these seeds was respectively 125%、965%、708%, and the germination force was 1%、598%、418%. With the increase of storage time, seeds vigor of three years would decrease gradually, but the loss rate of seed vigor from 2007 was the slowest compared with other years. After stored at room temperature, the seed vigor would decrease even faster with the increase of storage time, compared with that stored at lower temperature. Different media had a certain effect on seed germination and seedling growth. The results showed that seed vigor from an abundant year was better than that of off year, and would decrease even slower than that of off year with the increase of storage time. The storage at lower temperature was favorable to the maintenance of seed vigor. The reasons resulted in severe danger related to Tsinense seeds are as follows: (1) Small seeds contributed to the spread and dispersal of species, was not beneficial to the survival of seed and seedling. (2) Perennial low temperature was not suitable for seed germination and the formation of a seedling pattern; (3) Perennial moist environment was not suitable for seed living through cold period safely.     

Sequential temperature control of multi-phasic dormancy release and germination of Paeonia corsica seeds

Aims The physiological responses during dormancy removal and multi-phasic germination were investigated in seeds of Paeonia corsica (Paeoniaceae).Methods Seeds of P. corsica were incubated in the light at a range of temperatures (10–25 and 25/10°C), without any pre-treatment, after W (3 months at 25°C), C (3 months at 5°C) and W + C (3 months at 25°C followed by 3 months at 5°C) stratification, and a GA 3 treatment (250 mg·l^-1 in the germination substrate). Embryo growth, time from testa to endosperm rupture and radicle emergence were assessed as separate phases. Epicotyl–plumule emergence was evaluated incubating the germinated seeds at 15°C for 2 weeks, at 5 and 25°C for 2 months on agar water before transplanting to the soil substrate at 10, 15 and 20°C and at 15°C for 2 months on the surface agar water with GA 3 .Important findings Embryo growth, testa rupture, endosperm rupture (radicle emergence) and growth of the epicotyl were identified as four sequential steps in seeds of P. corsica. Gibberellic acid alone and warm stratification followed by 15°C promoted embryo growth and subsequent seed germination. Cold stratification induced secondary dormancy, even when applied after warm stratification. After radicle emergence, epicotyl–plumule emergence was delayed for ca. 3 months. Mean time of epicotyl–plumule emergence was positively affected by cold stratification (2 months at 5°C) and GA 3. P. corsica seeds exhibited differential temperature sensitivity for the four sequential steps in the removal of dormancy and germination processes that resulted in the precise and optimal timing of seedling emergence.     

Role of warm stratification in promoting germination of seeds of Empetrum hermaphroditum (Empetraceae), a circumboreal species with a stony endocarp

The broad objective of this research was to define the role of warm (≥15°C) stratification in breaking dormancy in seeds with stony endocarps that require warm-plus-cold (～0°-10°C) stratification for germination. This question was addressed using seeds (true seed + endocarp, hereafter called seeds) of Empetrum hermaphroditum. Only 2-5% of freshly matured seeds collected in September and October at five sites in Sweden germinated in light at daily alternating temperature regimes of 15°/6°, 20°/10°, and 25°/15°C. Dormancy was not due to impermeability of the stony endocarp surrounding each seed, and embryos did not grow prior to radicle emergence. Thus, seeds did not have physical, morphological, or morphophysiological dormancy. Long periods of either cold stratification (20 or 32 wk) or warm stratification (16 wk) resulted in a maximum of 22-38 and 10% germination, respectively, in light at 25°/15°C. After 12 wk warm stratification plus 20 wk cold stratification, 83-93% of the seeds germinated in light at the three temperature regimes. For a cold stratification period of 20 wk, germination increased with increase in length of the preceding warm stratification treatment. Gibberellic acid (GA(3)) promoted germination of 77-87% of the seeds. Based on dormancy-breaking requirements and response to GA(3), 62-78% of the seeds had intermediate physiological dormancy; the others had nondeep physiological dormancy. Contrary to suggestions of several other investigators that warm stratification is required to make the endocarp permeable to water via its breakdown by microorganisms, our results with E. hermaphroditum show that this is not the case. In this species, warm stratification is part of the dormancy-breaking requirement of embryos in seeds with intermediate physiological dormancy.     

Developmental Changes in Relation to Desiccation Tolerance of Archontophoenix alexandrae (Palmae) Seeds

Germination of Archontophoenix alexandrae seeds and embryos were studied under gradient water content treatments throughout the seed development phases of maturation in 2005 to investigate seed desiccation tolerance and storage characteristics. During the maturation process, seed water content decreased gradually from55 DAF (days after flowering) to 70 DAF, and seeds reached the maximum dry-weight at 90 DAF. Seed germinability appeared after 60 DAF. Seeds germinated with a temperature range from15℃- 40℃ under alternating photoperiod (14 h light, 10 h dark, 12μmol m^{- 2}s ^{- 1} ), while the best germination percentage was obtained between 30℃- 35℃. A maximum germination capacity reached at 70 DAF. However, seed germination was greatly inhibited by light. Desiccation tolerance of seeds and embryos increasedgradually from 55 DAF to 90 DAF and reached the maximum at 90 DAF with a semilethal water content of 0.18 g/g ( seed) and 0.3 g/g ( embryo) respectively. Rapid dehydration maintained higher seed germination percentage than thatof slow dehydration when drying to the same water content. Seeds with without water content treatments failed to germinate after 1 month storage under - 18℃, whereas appropriate desiccation treatment prolonged seed longevity under 4℃, 10℃ and 15℃ storage temperatures. It revealed obviously the recalcitrant characteristics of Archontophoenix alexandrae seeds torage behaviour which are tolerant toward neither deep desiccation nor low temperatures.     

温度对干旱、盐胁迫下两种黄芪属种子萌发和幼苗生长的影响

为探讨温度对干旱、盐胁迫下黄芪属种子萌发和幼苗生长特性的影响,以黄芪属蒙古黄芪和扁茎黄芪2种种子为研究对象,纯净水处理为对照组,NaCl、PEG处理为实验组,设置4个渗透势水平(0、-0.1、-0.3、-0.5 MPa),置于5种不同的温度(10、15、20、25、30 ℃)下,每日观察并记录两种种子萌发和幼苗生长情况。结果表明：旱盐胁迫下蒙古黄芪和扁茎黄芪种子萌发最适宜的温度分别为25和20 ℃左右;蒙古黄芪耐高温不耐低温,而扁茎黄芪恰恰相反;但25和20 ℃均适宜两种幼苗生长,包括胚根、胚轴和子叶的生长。蒙古黄芪各处理组(除未发芽的种子)的平均发芽时间都比扁茎黄芪长;NaCl胁迫程度的增加使得两种种子的最终发芽率降低,但蒙古黄芪的耐盐性高于扁茎黄芪;随着PEG胁迫程度的增加,二者的发芽均受到抑制,甚至会出现完全不萌发,但扁茎黄芪的耐旱性高于蒙古黄芪;在相同的渗透势时,尤其是-0.5 MPa,PEG比NaCl对两种种子的影响大;交互胁迫作用下,随着渗透势的增加两种幼苗的鲜重、干重以及胚根、胚轴、子叶的长和宽变化较大;利用Design Expert软件预测发现：温度25 ℃、NaCl渗透势为-0.1 MPa,温度24 ℃、PEG渗透势为-0.04 MPa的处理是蒙古黄芪种子萌发和幼苗生长达到最优化的组合;而扁茎黄芪最优化的组合则为23 ℃下NaCl渗透势为-0.07 MPa的处理,20 ℃下PEG渗透势为-0.13 MPa的处理。     

The Light-Sensitivity of Germination of Ficus benjamina var. nuda (Moraceae) Seeds and Its Ecological Significance

In this paper , Ficus benjamina L . var . nuda seeds were used as experimental materials, effects of temperature, light , phytohormone ( gibberellin , 6-benzyladenine and ethylene ) , nitrogenous compounds ( sodium nitroprusside,nitrate , and nitrite ) on seed germination were studied , and ecological significance of light in seed germination was discussed. Under alternating photoperiod (14 h light , 10 h dark , 12μmol m- 2 s - 1 ) , final germination percentage of seeds was 87. 5% , 100% , 100% , 100% , 98% , 89% and 100% , respectively, at 15℃ , 20℃ , 25℃ , 30℃ , 35℃ , 40℃ and 30℃􊄯20℃ , mean germination time of seeds was 34 . 7 d , 16 . 3 d , 5. 6 d , 4 .8 d , 6 . 4 d , 9 d and 6 .3 d , respectively. Germination percentage of seeds which were incubated for 35 d at 15℃ , 20℃ , 25℃ , 30℃ , 35℃ , 40℃ , 30℃􊄯20℃ and dark was zero , and these seeds rapidly germinated after addition of alternating photoperiod . Light intensity of 0 . 5 - 20μmol m- 2 s - 1 markedly increased final germination percentage of seeds . However , different light intensity influencedhardly final germination percentage of seeds, but altered germination rate of seeds . Under photoperiod of 24 h , final germination percentage of seeds notably increased with increasing length of light duration . The seeds treated for 24 h ,36 h , and 48 h by continuous light could germinate at subsequent dark. Different concentrations of exogenous gibberellin, 6-benzyladenine, ethylene, sodium nitroprusside , nitrate and nitrite could not replace light and not accelerate seed germination, and these seeds rapidly gained germinablity after addition of alternating photoperiod . Germination behavior of F. enjamina L . var . nuda seeds was closely related to long-term adaptation for tropical forest .     

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.     

度胁迫对罂粟种子萌发影响及其活力变化规律的研究

为妥善保存罂粟种质资源及防止种子老化,研究了温度对罂粟种子萌发及种子活力的影响。结果表明:罂粟为高温敏感低温萌发型种子,发芽的适宜温度为10～20℃,最适温度为18℃左右,低于5℃和高于20℃的温度,种子萌发受到抑制;在对其进行丸化包衣时,加热温度应控制在60℃以内,时间应控制在60min以内;在常温库存条件下,罂粟种子活力随贮藏年限的增加而下降,贮藏时间超过五年后,发芽率低于50%,不宜作种用,在作为种质资源保存时,须每隔五年繁殖一次。