SEED DORMANCY AND GERMINATION IN MELAMPYRUM LINEARE

Immature seeds of Melampyrum lineare Desr. have very high germination percentages and dormancy is induced in a variable fraction of the seed crop during ripening. Correlated with this is the endogenous gibberellin-like activity which is found in considerable amounts in immature seeds, less in batches of ripe seeds, and is not detectable in batches containing only dormant seeds. For germination dormant seeds require activation followed by cold storage. In the laboratory activation is produced by allowing moist, dormant seeds to respire freely for several weeks at 20 C, or by treatment with exogenous GA₃. Dormancy appears to be most directly related to inability of the embryo to hydrolyze the thickened, mannan-containing endosperm cell walls. Embryos excised from dormant seed can be grown on agar enriched with whole macerated dormant seeds or with the ethanol-extractable materials from these (mostly sucrose and a glycoside). However, dormant seed material does not support growth when extracted to remove benzene- and ethanol-soluble materials.     

沙冬青种子萌发及幼苗生长特性

沙冬青(Ammopiptanthus mongolicus)是亚洲中部荒漠特有种,由于其分布的环境条件特殊,现存植被天然更新困难,人工育苗、造林存在一定问题。为改善种皮透水性,获得整齐一致的发芽,分别用21.5 (室温)、40、60、80和90 ℃的温水浸种5 min。结果表明: 60 ℃温水浸种效果最好,与对照相比,显著地提高了种子发芽势,并有效地降低硬实率。对比分析了15、20、25、30、35和40 ℃环境温度下种子萌发的特性,种子发芽最适温度是30 ℃,而胚根及下胚轴伸长最快的温度为25~30 ℃。较低温度下种子发芽延续时间较长,并且种子萌发后下胚轴和胚根伸长缓慢,易形成畸形(胚根严重扭曲、缢裂)幼苗。15 ℃时畸形幼苗占发芽种子数的28.1%,而30~40 ℃时仅占5.2%~8.6%。温度过高不利于种子萌发及幼苗生长,40 ℃时,吸胀种子绝大部分丧失活力,发芽种子在35 ℃以上温度下生长2~3 d,胚根胚轴组织呈水渍状坏死。另外,催芽后的种子播种在河沙中子叶出土最快,出土率可达63%,显著高于在粘质壤土中出土率(11%)。不同粒径的种子播种后幼苗生长特性表现出一定的差异,粒径5 mm以下小粒种子播种后幼苗长势弱,苗期成活率低,生长70 d后幼苗成活率仅为35.4%,而粒径5 mm以上种子同期幼苗成活率达56.2%。据上述试验结果,结合自然分布区内环境条件的资料,分析了沙冬青濒危原因,并为植被恢复育苗措施提出建议。     

EFFECT OF HIGH PRESSURE ON GERMINATION OF SEEDS (MEDICAGO SATIVA AND MELILOTUS ALBA)

An increase in percentage germination is obtained with seeds of Medicago sativa exposed for 1 to 10 minutes at 2000 atmospheres hydraulic pressure at 20°C., dried, and germinated after 30 days; and from seeds of Melilotus alba under the same conditions of pressure, when exposed for 5 to 30 minutes, dried, and germinated 30 days later. Exposures to 500 atmospheres pressure was less advantageous for germination; the vitality of seeds normally germinating was more rapidly destroyed than the hard impermeable seeds rendered permeable by the pressure treatment. At 0°C., it required approximately 2½ times the exposure to 2000 atmospheres for seeds of Medicago sativa, and approximately 5 times the exposure for seeds of Melilotus alba, as it did at 20°C.     

中、旱生植物萌发特性及其与种子大小关系的比较

不同生境的植物有不同的生活史对策。该文对分布于河西走廓的42种常见中生植物和22种常见旱生植物种子的萌发特性以及种子大小对萌发能力的影响进行了比较。结果显示,64种植物中最终萌发率超过90%的有9种: 虎尾草(Chloris virgata)、蒲公英(Taraxacum mongolicum)、腺独行菜(Lepidium apetalum)、膜果麻黄(Ephedra przewalskii)、沼生蔊菜(Rorippa islandica)、白草(Pennisetum centrasiaticum)、霸王(Zygophyllum xanthoxylon)、反枝苋(Amaranthus retroflexus)和黑果枸杞(Lycium ruthenicum),占14.06%,其中黑果枸杞、腺独行菜、膜果麻黄、虎尾草的萌发在10 d内完成; 萌发率达到80%~90%的有5种: 毛果群心菜(Cardaria pubescens)、窄叶小苦荬(Ixeridium gramineum)、牛蒡(Arctium lappa)、鞑靼滨藜(Atriplex tatarica)和苣荬菜(Sonchus brachyotus)占7.8%; 萌发率达到60%~80%的有16种,占25%;萌发率在20%~60%的有17种,占26.56%; 萌发率不足20%的有17种: 柠条锦鸡儿(Caragana korshinskii)、野苜蓿(Medicago falcata)、扁蓄(Polygonum aviculare)、苦参(Sophora flavescens)、河西沙拐枣(Calligonum potanini)、白刺(Nitraria tangutorum)、甘草(Glycyrrhiza uralensis)、苦豆子(Sophora alopecuroides)、骆驼蓬(Peganum harmala)、画眉草(Eragrostis pilosa)、多裂骆驼蓬(Peganum multisectum)、老瓜头(Cynanchum komaroviil )、骆驼蒿(Peganum nigellastrum)、田旋花(Convolvulus arvensis)、酸模叶蓼(Polygonum lapathifolium)、卷茎蓼(Polygonum convolvulus)、蝎虎驼蹄瓣(Zygophyllum mucronatum),占25.56%。有26种植物的萌发持续在30 d以上,15种植物在15 d内完成萌发,有31种植物在1~3 d内开始萌发,4种植物在10 d以后才开始萌发。主成分分析和聚类分析显示,中、旱生植物的萌发主要有爆发型、过渡型、缓萌型和低萌型,以过渡型和缓萌型为主;中生植物中萌发率不足20%的有6种,占14.28%, 旱生植物中萌发率不足20%的有11 种,占50%,显示了较多的旱生植物有延迟萌发的行为,这种萌发的延迟及萌发时间的异质性可使物种在不可预测、高死亡风险的环境中仍能确保种的延续。中生植物的种子大小对萌发能力有显著的影响,小种子的物种有较高的萌发率和较快的萌发速率,并且完成萌发所需要的时间较短,而旱生植物的种子萌发不受种子大小的影响。以上结果说明中生植物和旱生植物长期适应于不同的湿、旱生环境,在不同的选择压力下,生活史对策也出现了较明显的差异。     

INTERACTION OF TEMPERATURE AND GIBBERELLIN ON POTATO SEED GERMINATION

Recently harvested true seed of potato frequently requires several months for complete germination. Gibberellic acid (GA₃) has a pronounced effect on seed germination, but this effect is influenced by temperature. As the temperature approaches 80 F, germination decreases considerably irrespective of GA₃ treatment. Potato seed germination is also favored by low temperature, but constant low temperature alone does not insure complete germination of dormant seeds. More than 95% germination of dormant seeds can be obtained within a week either by application of GA₃ at low temperature or by diurnal alternation of temperature. A possible mechanism for control of seed germination is discussed.     

成熟脱水对种子发育和萌发的作用

成熟脱水是正常性种子发育的末端事件。种子在成熟时胚的脱水耐性增加;当种子萌发时胚变得不耐脱水。当种子获得脱水耐性时,糖、蛋白质和抗氧化防御系统等保护性物质积累;当脱水耐性丧失时,这些物质被降解。成熟脱水是种子从发育过程向萌发过程转变的“开关”,它降低发育的蛋白质和ｍＲＮＡ的合成,终止发育事件和促进萌发事件。顽拗性种子不经历成熟脱水的发育阶段,对脱水高度敏感。     

沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响

该文研究了野外条件下不同深度的沙埋对沙鞭(Psammochloa villosa)种子萌发和幼苗出土的影响,以及温室条件下种子大小对不同深度沙埋后的种子萌发和幼苗出土的影响。结果表明,沙埋深度显著影响沙鞭的种子萌发率、幼苗出土率和种子休眠率。沙子表面的种子不能萌发。2 cm的浅层沙埋时的种子萌发率和幼苗出土率最高,1 cm 沙埋的种子萌发率和幼苗出土率次之。沙埋深度超过2 cm之后,沙鞭的种子萌发率和幼苗出土率与沙埋深度呈负相关。2 cm的种子休眠率最低。从2 ~12 cm,种子休眠率随着沙埋深度的增加而增加。在幼苗能够出土的深度(1~6 cm),幼苗首次出土所需的时间随着沙埋深度的增加而延长。种子大小对沙鞭的种子萌发率没有显著影响。但是在深层沙埋(6 cm)时,与小种子相比,大种子产生的幼苗的出土率较高。从2~6 cm,大种子形成的幼苗的茎长度都较长。     

矮沙冬青种子特性和萌发影响因素的研究

 对矮沙冬青(Ammopiptanthus nanus)种子的特性和萌发影响因素进行了初步研究,结果表明：种子不易传播;虫蛀率高,室温贮藏60 d的种子虫害率为38%;易形成硬实,含水量为7.68%的种子在30 ℃温水中浸泡90 h,只有33.33%能吸水膨胀。种子萌发时不需光,在15～30 ℃和室温（18～32 ℃）条件下,经9 d的萌发,发芽率均可达80%以上,30℃时萌发最快;在1～2 cm深的沙壤中,种子出苗率可达75%以上,超过3 cm显著降低,超过6 cm则低于20%;种子在沙壤中萌发时,沙壤的适宜湿度为19.35%～28.75%,高于32.43%或低于3.85%,很少有种子萌发;含水量分别为19.36%、10.64% 和7.68%的种子发芽率无显著差异,在-10 ℃和5 ℃下贮藏7个月,发芽率也无显著降低,但在室温和35 ℃下贮藏7个月则显著下降,发芽率下降的速度与种子本身的含水量和贮藏温度正相关;在湿度分别为7.41%、13.79%和28.57%的沙壤中播种育苗,幼苗死亡率高达77.49%、81.25%和89.49%,即使用三唑酮拌种,死亡率亦高达50.27%、69.53%和76.03%,幼苗死亡率与沙壤湿度正相关。     

SEED GERMINATION STUDIES IN MUSA. I. SCARIFICATION AND ASEPTIC GERMINATION OF MUSA BALBISIANA

Stotzky , G., Elsie A. Cox , and Roger D. Goos . (Central Research Labs., United Fruit Co., Norwood, Mass.) Seed germination studies in Musa. I. Scarification and aseptic germination of Musa balbisiana . Amer. Jour. Bot. 49(5): 515–520. Illus. 1962.—Methods for germinating seeds of Musa balbisiana Colla under aseptic conditions have been developed. Scarification was required for germination under these conditions, and mechanical was superior to chemical scarification. Various methods of mechanical scarification and cultural procedures were developed which facilitated the operation when large numbers of aseptic seedlings were required. Removing a chip from the lateral portion of the seed coat to expose the endosperm was the most effective method of scarification: germination percentages averaged 80%, and the time required for germination in sterile culture was shortened from the 3–6 weeks required for intact seeds in soil to 6–10 days. However, scarification did not shorten the time required for germination in soil, and seeds treated with some methods of mechanical scarification failed to germinate, as a result of their decomposition by microorganisms. The effectiveness of scarification in causing germination in aseptic culture is not presently understood, but, as the excised embryo exhibits no dormancy, the factors delaying germination apparently reside in other portions of the seed.     

不同水分胁迫条件下高粱种子萌发及吸水规律的研究

通过对抗旱性不同的高粱品种在不同水分胁迫条件下种子萌动、萌发及吸水过程的研究表明：高粱种子在萌动、萌发两个生理过程中对环境水分条件的敏感性不同,种子在萌动时比萌发时更适应低水环境。不同的高粱品种在萌动、萌发时所忍耐的临界环境水势也存在明显差异。种子胚和胚乳两部分的吸水过程具有不同的特点。胚部的干重含水量在吸水后一直急剧增加,直到萌动时达到最大,而胚乳的含水量除在前期快速增加外,随后缓慢增加,保持在相对稳定的水平。在种子吸水萌动过程中,种子胚与胚乳间,以及它们与环境间始终存在着水势梯度。     

真菌在兰科植物种子萌发生长中的作用及相互关系

本文从真菌在兰科种子萌发中的应用、真菌侵染的过程、种子和根系消化真菌的途径及共生真菌的分布等方面,综述了真菌与兰科植物种子萌发及菌根关系的研究进展,讨论了该研究的有关问题及真菌在兰科种子萌发中应用的前景。     

伊贝母种子萌发和籽苗建立

在子叶出土萌发的植物类型中,伊贝母种子萌发过程是罕见的。萌发初期,子叶优先生长。首先伸长而突破种皮,接着长出地面,此后,胚根才开始生长并产生不定根。种子萌发后形成特殊籽苗。在地上部分,子叶变绿,成为第一生长季唯一的同化叶;在地下部分,上胚轴扁平化,芽鳞肉质化,于是形成小鳞茎。籽苗形态属于最简化的类型。伊贝母的籽苗与其营养更新苗相比,是很弱小的。