散枝猪毛菜的种子多型性及其萌发行为

散枝猪毛菜(Salsola bracchita)主要分布于新疆准噶尔荒漠,具有很强的抗干旱和抗盐碱能力。该文对散枝猪毛菜的果实进行了观察,表明散枝猪毛菜具有4种类型的散布单位和果实,这4种果实在形状、大小、颜色和着生方式上均有显著差异。A型果实绿色、球形、大,着生方式为横生,宿存花被革质,背部有紫红色翅状附属物,直径为(2.161±0.138) mm,单粒重为(3.810±0.113) mg;B型果实绿色、大、扁平、长圆形,着生方式为直立,宿存花被革质,背部有翅状附属物,长为(2.062±0.188) mm,宽为(1.720±0.148) mm,单粒重为(2.665±0.113) mg;C型果实绿色、大、扁平、长圆形,着生方式为直立,宿存花被膜质,背部无翅状附属物,长为(2.239±0.277) mm,宽为(1.844±0.150) mm,单粒重为(2.723±0.559) mg;D型果实黄色、小、扁平、长卵形,着生方式为直立,宿存花被膜质,背部无翅状附属物,长为(1.678±0.163) mm,宽为(1.390±0.110) mm,单粒重为(0.928±0.025) mg。A型、B型和C型种子(果实)在5 ℃/15 ℃、5 ℃/25 ℃、15 ℃/25 ℃(暗12 h/光12 h)变温条件下萌发率>68%,且B型和C型种子比A型种子有较高的萌发率和萌发速率。D型种子在3种变温条件下萌发缓慢,最终萌发率始终维持在较低水平(<20%),划破果皮和种皮能够显著提高D型种子的萌发率和萌发指数,表明D型种子处于生理休眠状态。散枝猪毛菜的种子多型性是对荒漠异质环境的一种适应。     

准噶尔荒漠大翅霸王的生殖物候及结实格局

大翅霸王是多年生早春开花草本植物,是准噶尔荒漠地区的建群种之一。对野生大翅霸王的生殖物候、果实形态、结实格局和种子萌发特性进行了研究。结果表明:(1)大翅霸王的营养期生长期为20—30d,占整个生活周期的1/4,生殖生长期长约90—100d,其中花期约占1/2,果熟期短;(2)大翅霸王种群能产生3种形态的果实,可将植株分为5翅型、4/5翅型和3/4/5翅型植株,它们分别占种群植株数的3.45%、83.15%和13.40%。(3)依据个体大小的变化,3种类型果实在植株上的比例发生了显著变化。随植株个体的增大,三翅果所占比例逐渐增多,由0增加到2.65%;四翅果所占比例也增多,但在二级个体上有最大比例17.01%;五翅果实所占比例最高(80%)且没有显著变化。(4)三翅果、四翅果和五翅果内种子形态无差异,萌发率均小于30%;划破种皮能不同程度的加速和促进种子的萌发。大翅霸王特有的生殖物候和果实的表型多样性是其对荒漠干旱地区恶劣多变环境长期适应的结果。     

四种藜科植物多型性种子形态及萌发率对绵羊瘤胃消化的响应

藜科植物角果藜(Ceratocarpus arenarius L.)、盐生草(Halogeton glomeratus C.A.Mey.)、野榆钱菠菜(Atriplex aucheri Moq.)和紫翅猪毛菜(Salsola affinis C.A.Mey.)都具有种子多型性现象,每种植物均可产生2种不同类型的种子。以这8种种子为研究对象,采用瘤胃瘘管尼龙袋法,对瘤胃消化前后种子的长、宽、厚、千粒重和萌发率进行测定,研究了4种藜科植物的多型性种子对绵羊瘤胃消化的反应,并探讨了藜科植物种子多型性结实策略的意义。结果表明:种子经绵羊瘤胃消化后,种子颜色变暗,附属结构(苞片、种毛和种翅)被消化,暴露出内部的环形胚;随消化时间的延长,种子的长、宽、厚和千粒重形态学指标均显著降低(P0.05),且它们与消化时间之间分别具有形如Y=1.00+7.92e~(-0.04 X)(R~2=0.92,P0.0001)、Y=1.28+4.63e~(-0.11 X)(R~2=0.91,P0.0001)、Y=0.70+1.36e~(-0.09 X)(R~2=0.92,P0.0001)和Y=1.48+9.57e~(-0.20 X)(R~2=0.36,P0.0001)的函数关系;绵羊瘤胃消化能打破藜科种子的休眠特性,显著提高种子萌发率(P0.05),除野榆钱菠菜的小苞片种子随瘤胃消化时间的延长萌发率逐渐增加外,其余种子的萌发率均随瘤胃消化时间的延长呈现先增高后降低的趋势,且经瘤胃消化24 h后,8种种子的萌发率均40%,较消化前显著提高(P0.05),表明这8种种子均能通过绵羊进行消化道传播。同一种植物不同类型的种子对绵羊瘤胃消化的反应具有趋同性。4种藜科植物不仅能通过"两头下注"的繁殖策略适应严酷的荒漠环境,还能通过放牧绵羊进行种子的消化道传播,增加了种群扩散的途径,这是植物适应荒漠多变环境的一种生存方式。     

不同年际间异子蓬种子大小、萌发能力及结实格局

异子蓬(Borszczowia aralocaspica)为中亚荒漠特有种,在我国仅分布于新疆,其果实具有二型性。对同一生长地2006、2007、2008年异子蓬种子的大小、萌发特性及结实格局进行比较,结果表明:(1)年份和种子类型对种子大小和重量均有显著影响(P<0.05)。(2)2种类型种子具有不同的萌发行为,褐色种子萌发率高(>90%),萌发速度快,而黑色种子萌发率低(2006年的萌发率为31%),萌发速度慢;2种类型种子的萌发指数在不同年际间均差异显著。(3)不同年际间,种子总数、褐色种子数、黑色种子数均具有极显著差异(P<0.001),且随个体的增大黑色种子的比例逐渐减小,褐色种子的比例逐渐增大,并且黑色种子数目均高于褐色种子数目。该研究为深入认识异型种子的生态适应对策提供理论基础。     

荒漠植物准噶尔无叶豆结实、结籽格局及其生态适应意义

连续2a采用野外记录的方式对荒漠植物准噶尔无叶豆的结实、结籽格局进行了比较研究。结果表明:植株内花序生成格局表现为不同大小的花序在总花序中的比重与其结实率存在显著正相关,其中含有中等花数目的花序所占的比重及其结实率均最高,此种分布格局能够最大程度的保证繁殖成功;果序内果实生成格局表现为单花着生位置(从近柄端算起)与其结实量占总结实量的比例成线性负相关,花序基部的结实比例最高,顶部结实比例近为0;荚果内种子生成格局表现为:中间位置的胚珠败育率最低。另外,年际间荚果内仅有(1.08±0.03)粒和(1.07±0.03)粒种子能够完全成熟,此种结籽格局是准噶尔无叶豆保证后代质量的最佳策略。     

紫翅猪毛菜、钠猪毛菜不同个体大小繁殖分配差异及随海拔的变化

以新疆准噶尔盆地藜科猪毛菜属植物紫翅猪毛菜(Salsola affinis C.A.Mey)、钠猪毛菜(Salsola nitraria Pall)为研究对象,用繁殖分配比例的方法对比分析了两种猪毛菜不同海拔同一种群内不同个体大小繁殖分配的特点,并用异速生长模型分析了不同海拔繁殖生物量与营养生物量之间分配与个体大小的依赖关系。结果发现:1)不同海拔繁殖生物量(R)与营养生物量(V)呈不同程度的异速生长。紫翅猪毛菜随海拔的升高R-V的异速生长斜率显著升高,截距随海拔的升高没有显著增加;而钠猪毛菜的斜率随海拔升高显著降低,截距则显著升高。2)紫翅猪毛菜在较低海拔个体大小与繁殖分配呈负相关,在较高海拔呈正相关;钠猪毛菜在较低海拔个体大小与繁殖分配呈正相关,在较高海拔呈负相关;两种猪毛菜繁殖分配的适应对策相反。3)将同一种群个体大小分成大、中、小3种类型,多重比较发现紫翅猪毛菜在较低海拔,中小个体的繁殖分配显著高于大个体的繁殖分配;在较高海拔,大个体的繁殖分配显著高于中小个体的繁殖分配。钠猪毛菜在较低海拔,大个体的繁殖分配显著高于中、小个体的繁殖分配;在较高海拔,小个体的繁殖分配显著高于大、中个体的繁殖分配。综合分析认为:两个物种随海拔变化产生不同的繁殖分配策略,除遗传效应外,环境和个体大小对钠猪毛菜繁殖分配的变化均产生重要影响,而紫翅猪毛菜繁殖分配的变化主要由海拔差异导致。由于微生境对同一种群的个体大小产生影响,进而产生不同的繁殖分配模式,所以在干旱区更应重视个体大小对繁殖分配的影响。     

针毛收获蚁贮食行为及贮藏对种子活力的影响

针毛收获蚁Messoraciculatus(F .Smith)是我国西北荒漠草原生态系统中的种子收获性优势蚁类 ,收获、贮藏和取食多种 1年生荒漠植物种子 ,其中狗尾草、地锦、猪毛菜、雾冰藜最为典型 ,冬贮量分别为 1 92 ,1 1 2 ,0 5 1和 0 2 5g 1 0 0工蚁 ,分别占土壤种子库总量的 5 4 3 5 %～ 78 2 6% ,1 6 85 % ,1 1 7%和1 0 0 % ,占种子年产量的 79 5 6% ,1 6 73 % ,4 91 %和 3 1 49%。嗜于收获和贮藏的种子大小为 1 2～ 2 7mm ,重量为 0 8～ 2 0g 千粒。贮藏格局表现在不同穴巢深度所贮藏的种子种类和贮量不同 ;不同类型种子在贮藏小室中的堆放和混合方式不同 ;总贮量与社群总蚁量和蚁后数正相关。贮藏引起种子萌发能力显著降低。此外 ,对贮藏格局与种子形态特征的关系及该蚁在荒漠草原生态系统中的功能与地位进行了讨论。     

盐生植物角果碱蓬种子二型性对环境的适应策略

角果碱蓬(Suaeda corniculata)是藜科一年生盐生植物, 在我国分布于北方盐碱滩涂和盐碱荒漠地区。角果碱蓬具有棕色和黑色两种异型体种子(简称棕色和黑色种子)。对采自内蒙古鄂托克前旗盐渍化生境的角果碱蓬二型种子的形态、休眠和萌发特性开展对比研究, 测定了二型种子休眠和萌发行为对温度、光照和盐分(NaCl)的响应, 以揭示盐生植物异型种子对温带盐漠生境的适应对策。结果表明: (1)二型性种子在大小、种皮特性和结实比例方面有显著差异。与黑色种子相比, 棕色种子个体较大, 种皮透水性强。黑色种子与棕色种子的结实比例约为5.6 : 1。(2)新成熟的棕色种子的萌发对各温度梯度和光照条件不敏感, 萌发率较高(84%-100%); 而新成熟的黑色种子萌发率较低(8%-78%), 萌发对光照敏感。(3)黑色种子具有浅度生理休眠, 种皮划破、赤霉素处理和低温层积均可有效地提高种子的萌发率。(4)二型种子萌发对土壤盐分的胁迫具有不同的响应。与黑色种子相比, 棕色种子对盐分胁迫不敏感, 在较高的盐分浓度下仍有较高的萌发率, 低温层积处理能够降低黑色种子对盐胁迫的敏感性, 有效地提高种子的初始萌发率、萌发恢复率和最终萌发率。角果碱蓬二型种子不同的形态、休眠和萌发特性, 提高了该物种在高度异质性生境中的适合度, 对种群成功地适应温带盐漠环境具有重要的意义。     

河西走廊几种荒漠植物种子萌发特性研究

为了解植物种子萌发适应干旱环境的基本特性, 以河西走廊人工梭梭林中重要值较大的梭梭(Haloxylon ammodendron)、红砂(Reaumuria soongarica)、多枝柽柳(Tamarix ramosissima)、雾冰藜(Bassia dasyphylla)、沙蓬(Agriophyllum squarrosum)、刺沙篷(Salsola ruthenica)、蒙古虫实(Corispermum mongolicum)、白茎盐生草(Halogeton arachnoideus)、盐爪爪(Kalidium foliatum)、花花柴(Karelinia caspia)等10种植物种子为对象, 对其萌发率、萌发开始时间、平均萌发时间和萌发持续时间进行研究。结果表明: (1)10种荒漠植物种子在Log尺度下均呈正态分布,种子大小与萌发持续时间、萌发开始时间和平均萌发时间之间都呈显著正相关(P＜0.05), 而与萌发率呈极显著负相关(P＜0.01)。(2)萌发率正态分布曲线呈现单峰型, 除沙蓬、刺沙篷外, 其余8种植物种子萌发率大于20%, 说明荒漠植物具有较高的萌发特性;萌发开始时间呈单峰型, 1—3 d内开始萌发的植物占90%, 说明荒漠种子萌发时间较短; 持续萌发时间呈单峰型, 梭梭持续萌发时间最短; 平均萌发时间呈单峰型,红砂平均萌发时间最长。(3)聚类分析显示, 10种植物种子萌发特性分为快速萌发型和缓慢萌发型, 主要受外界环境长期适应和选择的结果, 也是荒漠植物生存策略的重要环节。     

青藏高原东缘31种常见杂草种子萌发特性及其与种子大小的关系

以青藏高原东缘31种常见杂草(禾本科、菊科和紫草科)植物种子为对象,在野外实验条件下,观测了其萌发特性,并对其萌发模式以及种子大小和萌发特征的关系进行了分析,以期对当地的杂草防治提供理论依据.结果表明,这些植物种子的萌发模式可以分为以下4种类型:爆发型、过渡型、缓萌型和低萌型.其中过渡型和缓萌型所占比例最大(各占32.3%),爆发型次之(25.8%),低萌型最小(9.7%).高峰萌发率与种子大小呈显著负相关,萌发高峰时间与种子大小呈显著正相关,萌发率、萌发指数与种子大小呈较弱的负关联,萌发开始时间与种子大小呈较弱的正关联,萌发持续时间与种子大小几乎无相关关系.     

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.     

Germination characteristics ofDiamorpha cymosa seeds and an ecological interpretation

Summary Laboratory-stored seeds ofDiamorpha cymosa (Nutt.) Britton (Crassulaceae) were germinated at monthly intervals starting shortly after maturity in late May and ending at approximately the time germination is completed in the field (November). Seeds were placed at 5, 10, 15, 20, 25, 30, 15/6, 20/10, 30/15 and 35/20°C at a 14-hr photoperiod (12/12 hr thermoperiods at the alternating temperature regimes) and in constant darkness. In June, seeds were almost completely dormant and thus germinated poorly or not at all under all conditions. As seeds aged from late May to November 1. germination at the 14-hr photoperiod increased in rate and total percentage, 2. the maximum germination temperature increased from 15 to 25°C at constant temperatures and from 20/10 to 30/15°C at the alternating temperature regimes and 3. the optimum temperature for germination increased from 15 to 15–20°C at constant temperatures but remained at20/10°C at alternating temperature regimes throughout the study. During the same period germination in constant darkness was negligible at constant and alternating temperature regimes. This pattern of physiological after-ripening apparently is an adaptation to summer-dry,winter-wet habitats such as rock outcrops of southeastern United States.A short period of illumination with white light given after a 12-hr imbibition period in darkness promoted germination in the dark at 25/10°C but not at 15 or 25°C. A short period of illumination given during the imbibition period was much less effective in promoting germination in the dark. Drying up to 7 days did not cause light-stimulated seeds to lose their ability to germinate in darkness. The light requirement for seed germination probably does not play a role in restrictingD. cymosa to its well-lighted habitats on granite and sandstone outcrops.This research was supported by funds from the University of Kentucky Research Foundation and by an NIH Biomedical Sciences Support Grant to the University of Kentucky.     

Foliage colour influence on seed germination of Bienertia cycloptera in Arabian deserts

Bienertia cycloptera (Chenopodiaceae) produces two types of leaf foliage colour (reddish and yellowish). In order to determine the role of leaf colour variation in regulating the germination characteristics and salinity tolerance during germination, a study was conducted on seeds collected from plants of both colours. Seeds with and without pulp were germinated under two illumination conditions (12‐h light photoperiod and continuous dark), three alternating temperature regimes (15/25°C, 20/30°C and 25/35°C), and several salinity levels at 20/30°C. Germination percentage was significantly higher for seeds without pulp as compared to the seeds with pulp. The response of B. cycloptera seeds to salinity depended on the leaf colour. Thus, the seeds collected from reddish coloured plants were able to tolerate higher salinity compared to those of yellowish coloured plant. The germination recovery results indicate that the seeds from both coloured plants could remain viable in saline condition and they will be able to germinate once the salinity level are decreased by rain. The production of different foliage colours by B. cycloptera seems to be an adaptative strategy which increases the possibility for establishment in unpredictable environments by producing seeds with different germination requirements and salinity tolerance.     

4种野生兰花种子特征及离体培养初报

对4种野生兰花--虾脊兰、羊耳蒜、石仙桃及密花石斛的果荚、种子、种胚性状进行初步研究,并对其种子进行离体培养。结果显示,4种野生兰种子为白色、淡绿或黄褐,呈纺锤体或椭球体。羊耳蒜、石仙桃及密花石斛种子具种孔,种胚浓密且清晰可见;种子萌发较快且萌发率高,其中以石仙桃及密花石斛种子萌发最快,仅需36d,萌发率高达100%。虾脊兰种子未见种孔,种胚不甚明显,种子萌发缓慢且萌发率低。4种兰科植物种子均以原球茎方式萌发,通过继代培养,获得了一批无菌苗。     

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.     

Effect of day length on germination of seeds collected in Alaska

Day length control can effectively limit seed germination to favorable seasons, but this phenomenon has been studied in relatively few wild plants. I tested species from interior Alaska for day length control of germination under controlled conditions, and I also monitored germination phenology in natural habitats. Unstratified and cold-stratified seeds were germinated on short (13 h) and long (22 h) day length and in the dark at constant and alternating temperatures. On long day length, unstratified Ledum decumbens and Saxifraga tricuspidata seeds germinated from 5 C to 20 C, but on short day length few or no seeds germinated at 5 C and 10 C and germination was reduced at higher temperatures. Unstratified seeds of Diapensia lapponica and Chamaedaphne calyculata germinated only at 15 C and 20 C on long day length, and short day length completely inhibited germination. Cold stratification widened the temperature range for germination on both long and short day lengths, but germination was still lower on short than long day length. Germination phenology in natural habitats was consistent with germination in controlled conditions. In these species, short day length and low temperatures interact to inhibit germination in the fall. After overwintering, seeds germinate in the spring at low temperatures and on long day lengths. The inhibitory effect of short day length is not important in the spring because day length is already long at snowmelt.     

不同居群准噶尔无叶豆果实和种子特性及种子萌发差异

研究准噶尔无叶豆(Eremosparton songoricum) 6个居群间果实和种子特性及种子萌发差异, 以揭示异质生境下准噶尔无叶豆果实和种子的生态适应机制。结果显示: 居群间准噶尔无叶豆的植株距离(F = 2.34, p = 0.03)和植株冠幅(F = 8.49, p < 0.01)存在显著差异, 沙漠北缘E、F居群和沙漠腹地C居群(受人类干扰剧烈)的植株距离和植株冠幅高于沙漠腹地A、B、D居群; 居群间准噶尔无叶豆果实和种子的长度、宽度、厚度、重量存在显著差异, 居群E、F和C的大部分参数显著高于其他沙漠腹地居群; 居群间果实多子性(F = 6.96, p < 0.01)也存在显著差异, 居群C的果实多子性最高((32.50 ± 4.79)%); 萌发结果表明, 居群间新鲜的成熟种子萌发不存在显著差异, 且萌发率都低于15%; 所有居群的大部分种子都存在物理性休眠现象, 人为划破种皮能显著提高种子萌发率, 但在低温(15/5 ℃)条件下, 所有居群的种子萌发率都较低, 说明低温抑制了种子萌发; 经人为划破种皮解除物理休眠后, 种子的休眠没有完全释放, 居群C、E和F (大种子居群)的种子萌发率显著高于居群A、B和D (小种子居群) (F = 30.77, p < 0.01), 说明准噶尔无叶豆种子不仅存在物理性休眠现象, 也可能存在生理休眠现象。不同程度的种子复合休眠可能是准噶尔无叶豆不同居群适应古尔班通古特沙漠的重要生存策略。     

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.     

Seed germination of Pilosocereus arrabidae (Cactaceae) from a semiarid region of south‐east Brazil

We evaluated the effect of temperature regimes (six constant and four alternating temperatures), light qualities (five red : far red ratios) and water potentials (ΨW; seven NaCl and polyethylene glycol 6000 [PEG] solutions) on the percentage and germination rate, as well as the post‐seminal development morphology, that allow Pilosocereus arrabidae seeds to germinate in a hot semiarid climate on the south‐eastern Brazilian coast. The results showed that seeds germinated similarly between constant and alternating temperatures, with an optimal germination at 25/20°C and 20°C. Pilosocereus arrabidae seeds were photoblastic positive and the final germination percentage was inhibited at low red : far red ratios. Maximum germination was obtained in distilled water (0 MPa) and decreases of Ψ_W in the solutions reduced the germination, which was lower in NaCl than in iso‐osmotic PEG solutions. Germination inhibition appears to be osmotic because the recovery response was high when non‐germinated seeds from both iso‐osmotic solutions were transferred to water. Seeds of P. arrabidae are small and germination is phaneroepigeal. Despite the slow growth typically seen in seedlings and adults of Cactaceae, germination in this species depends on the ability of the seeds to appropriately sense and react to environmental cues that correlate with times and places under low‐risk growth conditions.