光对种子萌发的影响机理研究进展

种子萌发是植物成功实现天然更新的关键环节, 需要适宜的温度、水分或光照条件。对于需光性种子, 光照是决定其萌发与否或萌发率高低的主要因素。光对植物种子萌发的影响不仅是一个复杂的生理过程, 也是受到调控的信号传递和基因表达过程。该文系统总结了影响种子萌发的光照属性、光与水/热耦合作用和种子的光属性(光敏色素)与种子萌发的关系, 明确了光调控种子萌发的生态意义; 重点综述了种子内光敏色素调控种子萌发的生理反应模式和光敏色素的光信号转导途径。试图为全面评估光对种子萌发的影响和将来开展更深入的研究提供参考。     

Penetration of light into soil and its role in the control of seed germination

Abstract Light transmitted through soil, and the leaf litter of two tree species, was measured using a spectroradiometer. In general, a greater penetration by longer wavelengths, especially far-red, was noted. This was most marked in a dry sand sample. The effect was less in the case of clay-loam aggregates. Moisture in the samples had an opposite effect in these two cases, causing an increase in transmission through sand but a decrease through clay loam aggregates. Reduction in particle size was found to reduce both the total light transmitted and the red/far-red ratio (R : FR). Red wavelengths were also more attenuated by a layer of freshly fallen oak (Quercus rotrur) leaves than were far-red wavelengths. A layer of Corsican pine (Pinus nigramaritima) needles however, was found to act as a neutral density filter over the 400 800 nm range. Prolonged exposure to soil-filtered light was found to affect the germination of seven species tested. Plantago major demonstrated an approximately linear decrease in germination with increasing depth. Rumex obtusifotius showed an apparent threshold response at 4 6 mm depth, as did Cecropia obtusifolia but at a slightly greater depth. Digitalis purpurea germinated very poorly in darkness, yet was extremely photosensitive with very high germination even at 10 mm depth. Galiutn aparine and Chenopodium album showed a two-phase response with germination reaching a peak at 2 mm depth. The implications for the function of the photoreceptor phytochrome in the control of germination are discussed in relation to soil-transmitted light and with regard to the results of the germination tests.     

Independent mode of action of cyanide and light on lettuce seed germination

Gaseous hydrogen cyanide stimulated subsequent lettuce seed ( Lactuca sativa L. cv. Grand Rapids) germination in darkness when applied for 1 or 22 h. Optimum concentrations were 5 × 10-5 M and 10-6 M, respectively. However, seeds did not germinate in the presence of HCN even at 10-8 M. The effects of unsaturating red light (R) and HCN (1 μM) showed a slight synergism. On the other hand, there was no difference between the effects of the sequences HCN – R and R – HCN. Stimulation of lettuce germination by an HCN pulse was practically not affected by far-red illumination, independently of the sequence of treatments. It was concluded that the primary stimulatory effect of HCN is of a regulatory character. Cyanide controls a regulatory point different from that affected by activated phytochrome.     

光质对杉木种子萌发及幼苗生长的影响

光是影响森林早期天然更新(种子萌发和幼苗生长)的重要因子之一.但光质对杉木(Cunninghamia lanceolata(Lamb.) Hook)早期更新的影响尚不清楚.为探讨光质对杉木种子萌发及幼苗生长的影响机制,以杉木种子为研究对象,通过设置8h白光(W)、8h红光(R)、6h红光-2 h远红光(R-FR)、4h红光-2 h远红光-2 h红光(R-FR-R)、黑暗(D,对照)5种不同光质处理,观察种子萌发及幼苗生长特征.结果表明,不同光质处理对杉木种子萌发影响显著,D和R-FR-R处理促进杉木种子萌发,R处理抑制种子萌发.最后一次照光选择红光处理(R和R-FR-R)能够显著促进杉木幼苗根和子叶的伸长,促进生物量积累以及增加叶生物量分配比例,但抑制茎的伸长,远红光处理则促进茎的生长.杉木种子为光不敏感种子,黑暗处理下萌发率最高,且远红光间断处理能够相对促进其萌发,说明杉木种子可以较好地适应异质光环境.     

光照和温度对百合属6种植物种子萌发的影响

对不同光照和温度条件对条叶百合（Lilium callosum Sieb.et Zucc.)、大花卷丹[L. leichtlinii Hook.f var.maximowicaii(Regel)Baker]、有斑百合[L.concolor Salisb.var.pulchellum(Fisch.)Regel]、川百合[L.davidii Duchartre)、毛百合（L. dauricum Ker-Gawl.)和东北百合（L.distichum Nakai)种子萌发的影响进行了研究。结果表明：光照对有斑百合、川百合和毛百合种子萌发有明显促进作用,可缩短种子萌发时间,提高种子萌发率。24h光照下种子萌发完全所需天数比12h光照少,种子萌发率以24h光照最佳。避光条件下温度对大花卷丹、有斑百合、毛百合、川百合及东北百合种子萌发率和萌发速度有影响,对条叶百合种子影响最大,其种子萌发最适温度为20℃,5～6d开始萌动,2～3周萌发完全,随着温度的升高或降低其种子萌发率下降。光照条件下,变温对种子萌发影响不明显。子叶留土类型的毛百合种子有二次休眼现象,9000lx光照能代替低温解除二次休眼。经不同前处理的百合种子萌发率和萌发速度不同。     

储藏条件和时间对六种多年生湿地植物种子萌发的影响

研究了储藏条件和时间对 6种湿地植物种子萌发的影响 ,以便为采用种子恢复和重建湿地植被提供指导。将新鲜种子在浸泡 -冷、湿 -冷、湿 /干 -冷和干 -冷 4种条件下储藏 3个月后再进行种子萌发 ,结果表明 ,普通野生稻 (Oryza rufipogon)和野慈姑(Sagittaria trifolia)在 3种水胁迫冷藏条件下的种子萌发率显著高于干 -冷储藏时的萌发率 ;柳叶箬 (Isachne globosa)和水毛花(Scirpus triangulatus)种子发芽率最高的储藏条件分别是浸泡 -冷或湿 -冷储藏和干 /湿 -冷藏。小慈姑 (Sagittaria potam-ogetifolia)和野荸荠 (Eleocharisplantagineiformis)在 4种储藏条件下的发芽率没有显著差异。将种子在干 -冷条件下分别储藏1个月、6个月、18个月和 30个月后再进行萌发 ,结果显示储藏时间延长显著提高了普通野生稻、柳叶箬、野荸荠和小慈姑的发芽率。野慈姑的发芽率在前 3个储藏期随储藏时间延长而提高 ,但 30个月后发芽率开始下降。水毛花在所有储藏期间的发芽率均小于 2 %。结果建议采用种子恢复和重建湿地植被时 ,将种子水胁迫冷藏利于种子的萌发。同时 ,结果也表明干 -冷储藏 30个月的种子仍可作为湿地恢复的种质资源     

The use of population parameters in the analysis of germination of lettuce seed

Probit analysis was used to determine the parameters of the germinating population of lettuce seed. Seeds were induced to germinate under different conditions and it was shown that with light induced germination the germinating populations were the same. However, when gibberellic acid (GA₃) was the inductive agent then the germinating populations were not the same being concentration dependent. – This type of analysis offers a rigorous comparison of different inductive treatments.     

光质及种子大小对普洱地区14种植物种子萌发的影响

以普洱地区14种常见植物种子为材料,在实验室条件下研究了其在白光、黑暗、红光和蓝光条件下的萌发特性,并分析了种子大小与萌发率、萌发速率、萌发开始时间的关系。结果表明:光质对四方蒿、沙针、尖子木、藿香蓟种子萌发率和萌发速率均有显著影响(P0.05)。光质对大叶斑鸠菊、云南山枇花、臭灵丹、车桑子、光萼猪屎豆、葫芦茶、云南地桃花、西南宿苞豆、岗柃、中国宿苞豆10个物种的种子萌发率和萌发速率均没有显著影响(P0.05),以上物种中除中国宿苞豆外,其他物种种子萌发率均在20%以下,处于休眠状态。四方蒿种子在白光(89.9%)和红光(84.7%)下萌发率最高,红光下种子萌发最快(4.93),蓝光下种子萌发开始时间最晚(11.3 d);沙针种子在白光下萌发率最高(80.4%)、萌发速率最快(2.71),在黑暗和蓝光下萌发率较低(43.9%和38%)、萌发速率最慢(0.73和0.85),白光、红光下萌发开始最早(11 d),黑暗条件下萌发开始最晚(21.7 d);尖子木种子萌发率在白光、黑暗、蓝光下均在86%以上,而红光下仅32%且萌发速率最慢(1.29),在蓝光下萌发开始时间最晚(13 d);藿香蓟种子萌发率和萌发速率在红光下最高(分别为71.3%和6.46),黑暗条件下最低(分别为42.5%和2.62);大叶斑鸠菊萌发开始时间在黑暗条件下最早(6 d),其次是白光下(7 d),蓝光和红光下较晚,分别为8 d和7.7 d。14个物种种子的萌发率与种子大小间均有显著负相关关系;种子萌发速率、萌发开始时间与种子大小间也有负相关关系,但不显著;种子大小与萌发率、萌发速率和萌发开始时间的关系不会随着光质的变化而发生变化。     

光照和温度对飞机草种子萌发的影响

通过在人工培养箱内模拟环境条件,探讨了不同光照和变温对飞机草种子萌发的影响。结果表明:在有光照状况下,飞机草种子在15℃/10℃～40℃/35℃条件下均能萌发,飞机草种子萌发的最适变温为30℃/25℃,萌发率达47.5%;而黑暗条件下,飞机草种子在15℃/10℃时不能萌发;在20℃/15℃～35℃/30℃范围内,温度越高,飞机草种子萌发高峰的出现时间越早;在15℃/10℃～30℃/25℃范围内,飞机草种子的萌发率随温度的升高而升高,超过30℃/25℃后,萌发率下降,而适当的光照有利于飞机草种子的萌发。飞机草成为入侵种并迅速扩散与其种子萌发对光照和温度的适应性密切相关。     

The effect of SAN 9789 and light on the germination of seeds from Taraxacum vulgare

Photoblastic seeds (achenes) of Taraxacum vulgare coll. were treated with a water solution of SAN 9789, 4-chloro-5 (methylamino) -2- (α,α,α-trifluoro- m -tolyl) -3(2H) pyridazinone. SAN-treatment increased the germination in darkness from 0 to 12%. An irradiation for 5 min with red light, giving a germination of 12% for seeds in water only, gave together with SAN treatment a germination of 60%. In both water and SAN, the effect of red irradiation could be reversed by a short irradiation (15 min) of far-red light. If far-red light was repeatedly given (5 min per h) it had hardly any effect on germination in water (4% germination), but for seeds in SAN solution, intermittent far-red light had a stimulating effect (63% germination). If far-red light was given continuously for 96 h, the germination in water was 1% and in SAN solution 17%. The results in the present paper indicate that SAN may broaden the concentration interval of P_fr for which germination is high.     

The effects of SAN 9789 and light on phytochrome and the germination of lettuce seeds

Photoblastic seeds (akenes) of lettuce (Lactuca sativa (L.) cv. Grand Rapids) were treated with SAN 9789 [4-chloro-5-(methylamine)-2-a, a, a,-trifluoro-m-tolyl-3-(2H)-pyridasinone]. The seeds weere placed in Petri dishes on filter paper soaked with water or SAN solution. The treatment increased the germination in darkness from 17% for water to 78% for SAN treated seeds. An irradiation with 5 min red light gave a germination of 98% both in water and in SAN. In water the effect of red irradiation could be reversed with a short irradiation (8 min) of far red light (17% germination), while in SAN solution the far red reversibility was poor (92% germination). If the far red light was given repeatedly (5 min per h) it had a slightly larger effect. If given continuously for 24 hours, the germination in water was decreased to 0.3% and in SAN solution to 9%. Possible mechanisms for the SAN effect are discussed.     

光照、水深交互作用对松嫩湿地芦苇种子萌发的影响

莫莫格国家级自然保护区位于松嫩平原西部, 以保护白鹤(Grus leucogeranus)等珍稀水禽及其栖息地为主要目的。扁秆藨草(Scirpus planiculmis)是莫莫格湿地的重要植物, 也是白鹤在该区停栖的主要食源植物。莫莫格湿地水文恢复后, 芦苇(Phragmites australis)等高大挺水植物大量出现, 阻碍了扁秆藨草的恢复。种子萌发是植物生活史的重要阶段, 对于认识野外植物群落动态和植被管理十分重要。该研究在人工气候箱模拟野外环境条件, 分析了光照(全光、遮阴、黑暗)、水深(0、5、15和30 cm)及其交互作用对芦苇种子萌发的影响。结果表明: 光照和水深变化明显影响芦苇种子的萌发; 最终萌发比例在遮阴和黑暗条件下明显比在全光下高, 在3种光照处理下较深水位(5-30 cm)均抑制了芦苇种子的萌发。芦苇种子萌发也明显受光照和水深交互作用的影响; 在全光条件下, 萌发比例在0 cm水深(86.67% ± 2.36%)显著高于其他较深水位; 在遮阴和黑暗环境下, 0 cm水深与其他水深处理间的差异明显缩小, 这应是在遮阴和黑暗条件下(不考虑水深)萌发比例较高的重要原因。因此, 在芦苇建群初期, 及时进行清除处理并保持一定地表水位可以限制芦苇通过有性繁殖更新, 同时改善地表光辐射等生境条件, 促进扁秆藨草恢复。     

The effect of light and seed mass on seed germination of common herbaceous species from the eastern Qinghai‐Tibet Plateau

Smaller seeds might encounter more severe selective pressure than larger ones because they have fewer food reserves and are more easily buried; thus, seed mass can be considered to be directly related to the effect of light on germination. To investigate the effect of light on seed germination and associated seed mass variation within a whole plant community, we compiled germination data for common herbaceous species from an alpine meadow on the eastern Qinghai‐Tibet plateau. The results showed the following. (i) Light had a general positive effect on seed germination. Under light, the proportion of species with lower germinability was decreased, mean germination percentage was increased by 20% and the speed of germination was doubled. (ii) Irrespective of light environment, species with medium‐sized seeds (seed mass ranging from 0.11 to 0.5 mg) had higher germination percentage and speed when compared with species within the largest seed mass group. (iii) The germination of smaller‐seeded species was more dependent on light stimulation than larger‐seeded ones. In darkness, the species within the smallest seed mass group had the lowest percentage and speed of germination; however, under light, the species within the largest seed mass group had the lowest percentage and speed of germination. Our results suggested that the germination characteristics and especially seeds’ response to light among species in the alpine meadow might be an adaptation to natural selective pressure.     

Photoinhibition of white clover seed germination at low water potential

Photosensitivity of germination of white clover ( Trifolium repens L. cv. Podkowa) seeds was studied under water deficit (low water potential) conditions at 25°C. The seeds showed negative photoblastism, which was most pronounced at -0.03 MPa polyethylene glycol solution. Inhibition was observed at two different wavelength bands with maxima at 660 nm (R) and around 730 nm (FR). Red light acted identically to white light (maximum inhibition ca 50%). The effect of far-red illumination was less inhibitory (20–30%). The photoresponse required long illuminations (3 h exposures); saturation level was at 0.1 W m⁻², independently of the light quality. White clover seed germination showed no reversibility of the effects of R and FR light. Prolonged illumination with R and FR increased the inhibition, and intermittent illumination had a higher effect than a continuous one. It was concluded that the photoinhibition of germination of seeds of Trifolium repens involves a reaction dependent on the rate of phytochrome interconversion, a property that is characteristic for the high irradiance reaction.     

The role of light in regulating seed dormancy and germination

Seed dormancy is an adaptive trait in plants. Breaking seed dormancy determines the timing of germination and is, thereby essential for ensuring plant survival and agricultural production. Seed dormancy and the subsequent germination are controlled by both internal cues (mainly hormones) and environmental signals. In the past few years, the roles of plant hormones in regulating seed dormancy and germination have been uncovered. However, we are only beginning to understand how light signaling pathways modulate seed dormancy and interaction with endogenous hormones. In this review, we summarize current views of the molecular mechanisms by which light controls the induction, maintenance and release of seed dormancy, as well as seed germination, by regulating hormone metabolism and signaling pathways.     

Effect of light on seed germination and seedling shape of succulent species from Mexico

Aims Light requirements for cactus seed germination have been considered to be associated with their adult plant height and seed mass, but this has not been thoroughly studied for other succulent species. In order to understand seed photosensitivity from desert species belonging to Asparagaceae (subfamily Agavoideae) and Cactaceae, we performed a germination experiment with and without light for 12 species and 2 varieties from 1 species from the Southern Chihuahuan Desert. We also determined if adult growth is totally determined by seedling 'growth form' in cacti.Methods We performed a germination experiment using light and darkness for 13 species from Southern Chihuahuan Desert: 10 rosette species (Asparagaceae), as well as 1 globose, 1 columnar and 2 varieties from 1 depressed-globose species (Cactaceae). The response variables were seed germination percentage and relative light germination (RLG). In addition, in order to determine if adult-globose cacti could have cylindrical seedlings, we calculated the shape index (height/width ratio) for Coryphanta clavata and Mammillaria compressa .Important findings All species were considered neutral photoblastic. Eleven species had similar seed germination in both light and dark conditions, and three taxa (M. compressa and the two varieties of Ferocactus latispinus) showed higher germination with light than without it. Agave salmiana, M. compressa and the two varieties of F. latispinus had higher RLG than the other species. Seed mass was an important factor because with higher seed mass there was lower dependence to light. These findings support the hypothesis that small seed mass and light requirements have coevolved as an adaptation to ensure germination. One adult-globose cactus species, M. compressa, and one adult-columnar species, C. clavata, had small seeds and neutral fotoblasticism. Seedlings from these two species exposed to light were cylindrical and those under darkness conditions were columnar. Perhaps seeds from this species are able to germinate in the dark because they produce columnar seedlings with the ability to emerge from greater soil depths where sunlight cannot penetrate.     

光照对辽东栎种子萌发和幼苗生长的影响

研究了不同光照梯度[55.4%自然全光照(natural sunlight,NS)、18.9%NS、5.5%NS、2.2%NS、0.5%NS和0.3%NS]对辽东栎种子萌发和幼苗生长的影响.结果表明:辽东栎种子的萌发率和萌发指数在55.4%NS处理达到最大,分别为72.5%和0.22,然后随着光照减弱而逐渐减小,在0.3%NS处理下最小,分别为42.5%和0.11;强光照对种子萌发进程有一定的延迟作用,萌发活力指数随着光照的减弱而增大(0.5%NS处理最大);强光下种子萌发的延迟可能是其对多种命运的权衡性选择.强光照有利于辽东栎幼苗基径和根系生长,以及幼苗干物质的积累,但株高最小(6.06 cm);不同光强处理的辽东栎幼苗具有较大的形态学可塑性,其幼苗阶段对光环境的适应性较强,0.5%NS处理的幼苗比叶面积、比枝长、比根长、叶片叶绿素b含量及叶绿素总量均最大,分别为142.57 cm2.g-1、156.86 cm.g-1、271.87 cm.g-1、0.07 g.cm-2和0.24 g.cm-2,55.4%NS处理下最小,分别为44.89 cm2.g-1、52.84 cm.g-1、101.98 cm.g-1、...     

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。     

Optical properties of Lactuca and Taraxacum seed and fruit coats: Their role as light filters

The optical properties of seed and fruit coats were examined from several varieties of light-sensitive achenes. Taraxacum vulgare L. and Lactuca sativa L. cv. Grand Rapids achenes with dark fruit coats and L. sativa cvs Huvudsallat and Issallat with white fruit coats were examined. Transmission spectra varied among the different achenes: white fruit coats of Lactuca acted as neutral density filters between 450 and 780 nm, whereas Taraxacum transmitted 2–36% in this region. The ribbed fruit coat structure greatly affected transmission so that at different locations in the same coat, transmission varied between 20 to 80% at 660 and 730 nm. Fruit coats of Grand Rapids lettuce and Taraxacum transmitted more far-red than red light with T₆₆₀/T₇₃₀ ratios of 0.8 and 0.4, respectively. The relationship between the optical properties of fruit coats and light-stimulated germination is discussed.     

Fiber optic studies of light gradients and spectral regime within Lactuca sativa achenes

Light gradients and spectral regime were measured in Lactuca sativa L. cv. Grand Rapids achenes using fiber optic microsensors. The distribution of scattered light across lettuce achenes was linear for 660 and 730 nm and non-linear for 450 nm light. Spectra for scattered light within intact achenes also showed a non-linear increase with wavelength. The preferential attenuation of blue light by the pericarp and seed explains in part the relative ineffectiveness of blue light with respect to red in triggering germination of lettuce. Calculated action spectra for phytochrome-stimulated germination agree closely in the red with experimentally derived action spectra; however, there is little agreement within the blue.