The effect of electron acceptors on the phytochrome-controlled germination of Paulownia tomentosa seeds

The effect of substances with different redox potentials in the phytochrome-controlled germination of Paulmtnia tomentosa seeds was examined. Up to 25% of water-imbibed seeds germinated upon irradiation with 5 min red light The seeds irradiated with 5 min red light and incubated in substances with redox potentials equal or higher than E'₀= 360 mV [potassium nitrate, potassium hexacyanoferrate (III) or potassium hexachloroiridate (IV)] and sodium nitroprusside germinated up to 80%. The optimal concentration was between 1 and 10 mM. Other electron acceptors such as 2.6-dichlorophenol-indoplhenol, phenazine methosulfate and methylene blue failed to produce and effect. The germination-promoting effect was obtained when the substances were supplied to the incubation medium from the onset of imbibition or at the onset of irradiation. Delay of application of these chemicals until after the red light treatment diminished their effectiveness and the effect was lost after 48 h. The escape from far-red reversibility was evident in the presence of substances which stimulated germination. The results presented support the view that phytochrome-broken dormancy of Paulownia tomentosa seeds is closely connected with redox changes.     

The effect of some growth regulators on light-induced germination of Paulownia tomentosa seeds

Grubišié, D., Konjevié, R. and Neškovié, M. 1988. The effect of some growth regulators on light-induced germination of Paulownia tomentosa seeds. - Physiol. Plant. 72: 525–528.
The germination of Paulownia tomentosa Steud. (Empress tree) seeds can be induced either by red light (R) or by exogenously applied gibberellic acid (GA₃). The R induced germination is completely suppressed by far red irradiation, abscisic acid (ABA) or by growth retardants such as ancymidol, tetcyclacis and paclobutrazol, though not by AMO 1618 or chloro-choline chloride (CCC). The inhibition caused by far red light (FR) and growth retardants can be overcome by GA₃, while the ABA-induced inhibition can be reversed by fusicoccin (FC), which does not reverse the inhibition caused by FR or growth retardants. It is noteworthy that the germination of light insensitive wheat, corn, alfalfa and mung bean seeds is not inhibited by growth retardants.     

Light and nitrate interaction in phytochrome-controlled germination ofPaulownia tomentosa seeds

Pulsed light and nitrate exhibit an interactive effect on the germination ofPaulownia tomentosa Steud. seeds that require long periods of light irradiation. Two pulses of red light (R), separated by an adequately long dark interval, substitute for continuous prolonged irradiation. A far-red (FR) pulse given at the beginning of the dark interval inhibits germination, while it has no effect if given at the end. The requirement for certain ratios of the far-red-absorbing form of phytochrome/total phytochrome (P_fr/P_tot) differs when a FR+R-pulse is given as the first or second of two pulses (FR+R or R) separated by a dark interval. An equal decrease of the P_fr/P_tot ratio leads to a more pronounced decrease in germination when the pulse of the same FR+R ratio is given as the second pulse at the end of the dark interval. The length of dark interval between light pulses needed for maximal germination, differed in (i) seeds with a natural requirement for long periods of light irradiation from that in (ii) seeds with their long light requirement imposed by two weeks of imbibition in darkness or by (iii) imbibition in 40% heavy water. However, a single R pulse was sufficient to induce a high percentage of germination if the seeds were supplied with KNO₃ (10 mM) from the onset of imbibition up to the onset of light. This effect decreased with a delayed time of application, and was prevented if FR preceded the KNO₃ application. We dedicate this paper to Professor Hans Mohr on the occasion of his 60th birthday     

绒毛番龙眼种子萌发生态特性的研究

就温度、光照、土壤水分条件对绒毛番龙眼 ( Pometia tom entosa( Bl.) Teysm.et Binn.)种子萌发的影响及种子寿命进行了研究 ,结果表明 ,绒毛番龙眼种子萌发的适宜温度为 2 0～ 35°C,最适温度为 30°C;周期性光照条件下的萌发优于全黑暗条件 ;适宜土壤含水量为 2 0 %～ 70 % ,最适为 6 0 % ;在室内自然摊放条件下 ,9d后发芽率减半 ,16 d后完全丧失发芽能力。研究认为 ,目前绒毛番龙眼的濒危状态主要是由于滥砍乱伐和森林破坏造成的 ,由于其种子具有顽拗性种子的一些特点 ,该物种宜采取活体保存的方法 ,以就地保护为主 ,活植物迁地保护为辅。     

Cryptic seed heteromorphism in Packera tomentosa (Asteraceae): differences in mass and germination

Seed mass variation and heteromorphism may afford plant species differential germination behavior and ultimately seedling success, particularly in disturbed habitats. We asked whether such variation occurs in Packera tomentosa (Michx.) C. Jeffrey (Asteraceae), a clonal species of the southeastern USA. Seed mass was compared within and among genetic individuals differentiated using amplified fragment length polymorphisms. We compared central and peripheral seeds produced by disc and ray florets, respectively, for their morphology, mass, and germination behavior, including response to water availability, aging, and cold stratification. Seed mass was highly variable both within and among individuals and influenced germination behavior. We found cryptic seed heteromorphism in P. tomentosa. Central and peripheral seeds had similar morphologies but dissimilar mass and biomass allocation. We used failure time analysis to detect different germination behavior. Central seeds were heavier, contained larger embryos, and germinated faster and at a higher proportion in most germination studies. Highly variable mass and heteromorphism of seeds may allow persistence of P. tomentosa in its disturbed habitats. Based on our results, some future studies of Asteraceae species with disc and ray florets may need to account for possible differences between seed types, even when morphological differences are not apparent. Evaluation of individual seed mass and maternal differences in germination studies may assist in the detection of cryptic seed heteromorphism, a phenomenon thought to be common, yet rarely documented.     

The influence of temperature during seed development on the germination characteristics of millet seeds

Abstract. The cardinal temperatures, rate of germination and final percentage germination of pearl millet seeds were measured for seeds raised in greenhouses maintained at mean air temperatures of 19, 22, 25, 28 and 31°C. The results showed that cardinal temperatures for germination are unaffected by the temperature during seed development and growth. However, the conditions during seed growth did affect seed size and, subsequently, germination rate and seed viability.     

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。     

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。     

正交试验法优选毛泡桐中乌索酸提取工艺条件

采用正交设计L9(34)方法,考察乙醇浓度(A)、超声时间(B)、超声功率(C)、料液比(D)对乌索酸提取率的影响,用高效液相色谱法测定含量,并与常规提取法进行对比,确定了毛泡桐中乌索酸的最佳超声提取工艺条件。所考察的因素对毛泡桐中乌索酸提取的影响按各因素作用主次顺序为:乙醇浓度>料液比>超声时间>超声功率;乌索酸超声提取的最佳条件为:A3B3C2D1,即毛泡桐叶粉末用6倍量体积分数95%乙醇超声提取2 h,超声功率为200 w。与常规的提取方法相比,超声提取具有提取时间短、操作简单、提取率高、无需加热等优点。优选的工艺条件稳定,操作简便,方法可行,可用于毛泡桐中乌索酸的提取。     

不同种源毛泡桐种子发芽状况及其聚类分析

本文分析了不同毛泡桐种子的发芽状况并对其进行了聚类分析．结果表明,光照处理有利于提高毛泡桐种子的发芽率和发芽势,室温贮藏不利于种子活力的保持,根据不同条件下毛泡桐种子发芽率和发芽势的差别,利用聚类方法将其划分为四组,该结果为泡桐引种培育新品种奠定了基础．     

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。     

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。     

Role of endogenous hormones,glumes, endosperm and temperature on germination of Leymus chinensis (Poaceae) seeds during development

Aims Leymus chinensis is an original dominant plant in the Songnen grassland, and it has great value for restoration of severely degraded land. However, seeds are dormant, and low germination percentage is a problem for restoring L.chinensis grassland. The mechanism of seed dormancy is not been well understood. The primary aims of the present study were to investigate the dormancy mechanism of L.chinensis seeds (caryopses) with reference to the role of embryo-covering layers, endogenous hormones and temperature.Methods Changes in concentration of the endogenous hormones GA 3, indoleacetic acid (IAA), zeatin riboside (ZR) and abscisic acid (ABA) in L.chinensis seeds from anthesis to maturity were measured by the enzyme-linked immunosorbent assay method. Germination at different stages of maturity were tested at 16/28°C, 5/28°C and 5/35°C for intact seeds with glumes (control), intact seeds with glumes removed (naked-whole seeds) and intact seeds with glumes and one-half of the endosperm removed (naked-half seeds).Important findings Of the four endogenous hormones monitored, only the concentration of ZR differed significantly between the beginning and the end of seed development (increased); the GA 3 /ABA ratio also did not differ. Rank of germination percentage of control at the three temperature regimens was 5/28°C> 16/28°C> 5/35°C. Germination percentage of the naked-half seeds reached 100% under the three temperature regimens. We concluded that dormancy of L.chinensis seeds is not mainly controlled by endogenous hormones. Germination temperature, mechanical resistance of glumes and inhibition of endosperm are the main factors controlling dormancy and germination of L.chinensis seeds.     

Phenotypic and ploidy status of Paulownia tomentosa trees regenerated from cultured hypocotyls

Shoots of Paulownia tomentosa Steud., the Empress tree, were regenerated from cultured hypocotyl segments. The phenotypic and ploidy status of a population of regenerated trees was investigated and compared with a control population of trees grown from seed. Five of the six measured phenotypic characteristics were not significantly different between both populations of plants. Twenty of twenty-one shoots had the normal diploid chromosome number and one was apparently mixoploid. Five phenotypic variants were recovered, including a variegated variant that appearsr to be a plastid chimera undergoing a segregation of normal and mutant plastids. The variegated variant was the only stable variant. All other variants displayed typical morphology in their second year of growth. Precocious flowering of five regenerated plantlets occurred in their first year of growth. These plants were derived from different hypocotyls and did not flower the subsequent year.     

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.     

果翅对梭梭属(Haloxylon)种子萌发行为的调控

种子萌发行为的受控机制是生殖生态学的重要研究内容。通过果翅存留实验研究了在不同贮藏时期果翅对梭梭和白梭梭种子萌发的影响。结果表明：①新成熟的梭梭种子具有高的萌发率（〉90％）。梭梭果翅对秋天新成熟的种子萌发有显著的抑制作用（萌发率〈50％）,使种子处于强迫休眠状态;果翅对种子萌发的抑制作用随着贮藏时间的推移逐渐降低,到翌年春天（4月）这种抑制作用已完全解除,果翅对梭梭种子的抑制主要是化学抑制。果翅对梭梭种子萌发行为的调控作用确保了种子在合适的时间萌发与种群的成功定居,也正是梭梭在荒漠地区广泛分布的主要原因。②新成熟的自梭梭种子萌发率为59．5％,贮藏1个月后达到80％。表明种子存在短时期的生理后熟现象。白梭梭果翅在每一贮藏时期对其种子的萌发都具有显著的抑制作用,翅＋种子（将果翅与种子剥离。一起放人培养皿中）也部分地抑制种子的萌发,因此,果翅对白梭梭种子萌发的抑制既有化学抑制也存在机械抑制。果翅对种子萌发的抑制,限制了白梭梭的分布。     

Effect of light and temperature on the germination of lettuce seeds

A short period (15–30 min) at 30° C promotes germination of seeds of Lactuca sativa L. cv. Repolhuda in darkness. Far-red light reverses this stimulation, and the escape curves for phytochrome and high-temperature action are quite similar, indicating that the two factors act at a common point in the chain of events leading to germination. It is suggested that high temperature acts by decreasing the threshold of the active, far-red absorbing, form of phytochrome (Pfr) needed to promote germination.Abbreviations FR far-red light - Pfr far-red-absorbing form of phytochrome - R red light     

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.     

温度对四川小金县岷江柏种子发芽的影响

通过对采自四川小金县的岷江柏(Cupressus chenggiana S. Y. Hu)种子发芽特征的研究,分析不同温度对种子发芽的影响.结果表明,采自四川小金县的岷江柏种子发芽周期为20 d,其中0 ～5 d为萌动期,5 ～15 d为高峰期;发芽温度为5℃～30℃,适宜发芽温度为10℃～25℃,种子最适发芽温度在2003年1、4、7和10月分别为25℃、15℃、20℃和20℃.岷江柏种子的最适发芽温度和贮藏过程中的发芽特征与环境温度有着密切的关系.     

A bimodal germination response to temperature in cocklebur seeds. I. Cyanide-sensitive and cyanide-resistant respirations

Abstract. Pre-imbibed cocklebur ( Xanthium penn-sylvanicum Wallr.) seeds displayed bimodal germination-temperature responses with two optima at 8 and 33° C. Such germination responses occurred subsequent to bimodal respiration-temperature upsurges at lower and higher temperature regions. At lower temperatures, cocklebur seeds respired predominantly through a cyanide-sensitive cytochrome pathway. A rise in temperature resulted in a marked increase in flux via an alternative pathway, a propyl gallate- (PG) or benzohydroxamic-acid- (BHAM) sensitive pathway, thus resulting in an increase in the ratio of this pathway relative to the cytochrome pathway. Both an increased capacity for the alternative pathway and an increase in the ratio of this pathway to the cytochrome pathway were obtained when pre-imbibed seeds were exposed to either 8 or 33°C for a short period. The effects of low temperature were reduced as the exposure time was prolonged beyond 3d, resulting in a reduction in germination. Neither PG nor BHAM had an inhibitory effect on the chilling-induced germination, but the germination-stimulating effect of high temperatures was less pronounced in the presence of PG or BHAM. At high temperatures, on the other hand, KCN and NaN₃ were ineffective or, rather, slightly inhibited germination. It was thus concluded that low and high temperatures exert their germination-stimulating effects by an essentially similar manner which increases fluxes both via the cytochrome pathway and, especially, via the alternative pathway and, as a result, raises the ratio of the latter to the former.