返魂草种子休眠机理及处理技术研究

目的：为解决返魂草驯化栽培中种子发芽率低的问题。方法：研究返魂草种子的休眠特性，并进行解除种子休眠的种子处理试验。结果：返魂草种子具有种皮吸水障碍性休眠特性，并含有抑制发芽物质。结论：浸种、低温及赤霉素处理均可打破种子休眠。     

结缕草种子生活力的加速测定法

本文介绍一种快速测定外具蜡质层的日本结缕草种子生活力的方法（以下称“快速法”），该方法可以用来分析造成结缕草籽休眠的主要因素及打破休眠的方法，“快速法”特别适用于有外具蜡质的蜡籽的生活力的测定，极具推广价值。     

结缕草直播建坪技术综述

结缕草(Zoysia japonica Steud)是中国重要的乡土草种,主要作为草坪草利用,是唯一的种子可国产化的草坪草。在中国,随着破除结缕草种子休眠技术在种子生产中的应用,结缕草种子直播建坪技术在实际运用中越来越广泛。结合结缕草的特性,作者综述了直播建坪的播种时间、播量、破除种子休眠和养护管理等关键技术,为实际运用提供有用参考,进一步推广其在城市绿地和运动场地中的应用     

结缕草种子打破休眠的研究

针对结缕草萌发困难限制该草种广泛利用的问题，研究了磨擦处理，不同浓度的硫酸，强碱以及双氧水，激素处理两种结缕草－－半引Ⅲ号结缕草和青岛结缕草。结果表明供试种子经磨擦处理，一定浓度的硫酸，强碱，双氧水浸种都能提高种子发芽率和幼苗的生活力，特别是采用7％－10％的NaOH和KOH溶液浸种15min ,或处理之后再加入0.04g/L-0.16g/L的赤霉素或1.0g/L乙烯利浸种24h的综合处理，可使两种结缕草种子的发芽率接近他们潜在的发芽能力，并且使发芽天数缩短5－6天。     

鹿茸草种子的休眠与萌发

将新收获的鹿茸草种子在25℃和30℃恒温条件下或20～30℃室内变温条件下做发芽试验均未能发芽,但TTC染色试验结果表明其具有生活力,由此证明该种子具有休眠特性.打破休眠试验结果表明:2～5℃低温湿藏处理80d可使其发芽率达67.5%,用200mg/L GA3浸泡48h可使其发芽率达86.9%.干种子在-18℃的密封条件下贮存2年后,仍保持有52%的发芽能力.     

滇龙胆草种子休眠机制与萌发特性初步研究

为探索滇龙胆草种子的休眠机制及解除种子休眠的措施,对滇龙胆草种子采取了休眠程度测定、种子萌发时吸水规律测定、种子休眠机制的生物学鉴定、室温贮藏下种子生活力变化测定及低温层积处理效果.结果表明:新采集的滇龙胆草种子较经低温(4℃)贮藏了1年的种子萌发时间长;由于种皮相对透水、透气差,在室温下种子需经39 h才能充分吸水膨胀;新采集的滇龙胆草种子中有可溶于水的萌发抑制物,其水浸提液对白菜籽萌发及胚根生长均有抑制作用;滇龙胆草种子在室温下贮藏时,随着贮藏时间的延长,其活力逐渐下降,在生产实践中,种子在室温下的贮藏时间不宜超过6个月;一定时间的低温层积处理有利于种子萌发,为缩短刚采收种子的萌发时间,50 ～80 d的低温层积处理效果相对较好.     

切割种子对二穗短柄草种子休眠及萌发的影响

为打破二穗短柄草种子的休眠,对二穗短柄草种子进行了6种类型的处理:(1)不切割;(2)切掉胚乳1/4;(3)切掉胚乳1/2;(4)在背对胚的一面划一不伤及胚的裂缝;5)切掉胚乳3/4;6)全部切掉胚乳,只剩下胚,以探索各处理对种子休眠的影响。切割种子是打破二穗短柄草种子休眠的有效方法。方差分析显示,不同切割处理对打破种子休眠有着显著的差异,其萌发率的高低顺序为(6)(5)(4)(3)(2)(1)。种子休眠被打破的难易,与种子切割点到胚的相对距离以及切割后剩下部分的百分比皆成负相关关系。分析表明,在自然条件下部分地损伤种子的胚乳,可以增加种子萌发的几率。作为模式植物,二穗短柄草的休眠特性对进一步研究植物种子的休眠机理很有意义。     

大麦种子破除休眠快测发芽率方法研究

大麦种子破除休眠快测发芽率方法研究江苏省临海农场种子公司杨和宏，宋余军我场是沿海垦区啤酒大麦主要生产基地，每年向社会提供１４００．万公斤左右的优质啤酒大麦原种，但由于啤酒大麦种子的休眠作用，而影响其质量效应。以往我们采用生活力测定方法代替发芽率，但结...     

休眠与解除休眠的玉米种子对田间种植鉴定差异研究

新收后的玉米种子在一定时间内具有休眠性，处于休眠状态的种子与解除休眠的种子对田间种植鉴定结果存在显著差异。指出，进行田间种植鉴定必须使用真正成熟的种子。     

草本花卉种子休眠分析探讨

通过对金鱼草、千日红、矮串红、紫菜莉等25种草本花卉种子休眠时间与打破休眠方法连续试验观察，大概总结了其休眠时间范围，并根据生产实践及种子特性对影响种子休眠的主要因素进行了初步探讨。认为种皮油脂、坚硬种壳、种毛、干燥、内源激素成分水平是引起种子休眠的主要因素，同时对打破休眠的方法进行了初步探讨。     

破除种子休眠方法研究进展

破除种子休眠的方法主要有物理方法、化学方法、生物方法.物理方法包括温度处理、机械处理、射线、超声波处理和电场处理、干燥后熟和层积处理;化学处理包括激素处理、无机化学药剂处理和有机化学药物处理.许多植物种子的休眠是综合休眠类型,此类植物种子的休眠需综合方法来破除休眠.     

早粳中组8号种子休眠的研究

中组8号（japonica）是一个具有深度休眠的优质早粳品系，休眠期为45天。该试验分别对其完整种子、剥壳种子及经干热预处理的完整种子进行试剂处理，并测试了其种子浸出液对水稻非休眠品种种子萌发的影响。研究表明，①55℃干热处理7天、0.1mol／LHNO3或0.1mol／LHC1浸种1天及其剥壳处理都能有效的打破其休眠，50ppMGA3效果不大，0.1mol／LKNO3及0．4％H2O2无效；②对于剥壳种子，0．1mol／LHNO3或0.1mol／LHC1有毒害作用，GA3有明显的促萌作用，KNO3或H2O2仍然无效；③干热处理后的完整种子对一些试剂的反应与未处理的相似，但该处理不能增强高酸度对完整种子的促萌作用；④H2O2具有依赖GA3的促萌作用，但这种作用机理尚不清楚；⑤抑萌物质存在于胚及胚乳中，种壳中不存在。通过分析认为中组8号的种子休眠主要由种壳透气性差引起，同时内源激素水平也对萌发产生一定程度的不利因素。     

Seed dormancy mechanisms in warm season grass species

Embryogenic protoplasts of Dancy tangerine (Citrus reticulata Blanco) were X-ray irradiated at three doses and electrofused with iodoacetic acid-treated embryogenic protoplasts of Page tangelo (C. reticulata Blanco × C. paradisi Macf.). Shoots could regenerate only from the fusion combination with the lowest irradiation dose, but were recalcitrant to rooting. In vitro grafting was applied to obtain complete plants. Chromosome examination showed that the plants contained mainly diploid and aneuploid cells, together with few tetraploid cells, indicating that they were mixoploids. Random amplified polymorphic DNA analyses with 10-mer arbitrary primers confirmed the plants as true somatic hybrids. This is the first report on regeneration of mixoploid hybrid plants via protoplast asymmetric fusion in Citrus. Negative effects of ionizing irradiation on regeneration of embryoids and plantlets and possible agronomic interest of the mixoploid plants are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Wheat ABA-insensitive mutants result in reduced grain dormancy

This paper describes the isolation of wheat mutants in the hard red spring Scarlet resulting in reduced sensitivity to the plant hormone abscisic acid (ABA) during seed germination. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature seeds. Wheat sensitivity to ABA gradually decreases with dry after-ripening. Scarlet grain normally fails to germinate when fully dormant, shows ABA sensitive germination when partially after-ripened, and becomes ABA insensitive when after-ripened for 8?C12?months. Scarlet ABA-insensitive (ScABI) mutants were isolated based on the ability to germinate on 5???M ABA after only 3?weeks of after-ripening, a condition under which Scarlet would fail to germinate. Six independent seed-specific mutants were recovered. ScABI1, ScABI2, ScABI3 and ScABI4 are able to germinate more efficiently than Scarlet at up to 25???M ABA. The two strongest ABA insensitive lines, ScABI3 and ScABI4, both proved to be partly dominant suggesting that they result from gain-of-function mutations. The ScABI1, ScABI2, ScABI3, ScABI4, and ScABI5 mutants after-ripen more rapidly than Scarlet. Thus, ABA insensitivity is associated with decreased grain dormancy in Scarlet wheat. This suggests that ABA sensitivity is an important factor controlling grain dormancy in wheat, a trait that impacts seedling emergence and pre-harvest sprouting resistance.     

Quantitative trait loci for seed dormancy in rice

Seed dormancy (SD) is controlled by its own complicated genetic factors and environmental factors. SD is an important trait affecting grain yield and quality in cereal crops. A population comprising 240 recombinant inbred lines (RIL) was used for detecting quantitative trait locus (QTL) for SD in rice. To minimize the effect of environment, data for lines for which the optimum temperature during the late ripening stage is either below 20°C or above 30°C were excluded from the analysis, which left 185 lines. In a dynamic germination test of the parents of the population, Minghui 63 showed clear SD and Zhenshan 97 showed none. The seeds of each RIL, harvested 32 days after heading, were divided into two lots: seeds in one lot were sown immediately, without any treatment to break their dormancy, whereas seeds in the other lot were sown after they had been exposed to dry heat (50°C) for 72 h. Composite interval mapping showed the presence of qDGE1, qDGR5a, qDGR5b, and qDGR7 in the first lot whereas only qDGR7 was detected in the second lot––which had been treated to break SD––indicating the strong influence of qDGR7 in controlling SD. A recently cloned Sdr4 is also located in the qDGR7 region. Coincidently, three rice homologues of Arabidopsis SD gene DOG1 were found in qDGE1 and qDGR5b regions where no SD QTL had been reported so far. These results indicate that the QTL found in this study are reliable, and that it would be worthwhile to clone qDGE1 and qDGR5b.     

Geographical differentiation and diallel analysis of seed dormancy in barley

Seed dormancy is one of the most important parameters affecting the malting process and pre-harvest sprouting in barley (Hordeum vulgare L.). Variation of seed dormancy in 4365 cultivated and 177 wild barley (ssp. spontaneum) accessions derived from different regions of the world was investigated in Okayama University, Kurashiki, Japan. Seed dormancy of each accession was estimated from their germination percentages at 0, 5, 10 and 15 weeks post-harvest after-ripening periods. All of the wild barley accessions showed less than 10% germination at 0 week after-ripening period. Level of seed dormancy in 4365 cultivated barley accessions showed a clear geographical differentiation. Seventy seven percent of Ethiopian accessions showed high germination percentages, while 86% of Japanese, Turkish and North African accessions showed low germination percentages at 0 week after-ripening period. A half diallel cross using eleven barley accessions with different level of dormancy revealed that seed dormancy was predominately controlled by additive gene effects. These results suggest that large genetic diversity for seed dormancy in barley is explained as different levels of additive accumulation of genetic factors. Barley varieties showing appropriate dormancy could be developed by crossing among barley germplasm accessions used in the present study.     

A study of grain dormancy and viability in spring barley

In field experiments carried out between 1989 and 1991, spring barley was sampled to observe changes in the grain viability and dormancy during grain filling. The weather during the grain filling periods of 1989 and 1990 was unusually warm and dry, and the crop in 1989 was affected by drought. Some grains were capable of germination shortly after anthesis, but were dormant. Dormancy declined with increasing maturity, but was prolonged by low temperatures and reduced by warm weather. Differences were found in the dormancy characteristics of the two cultivars tested. Apart from grains at the extremities of the ear, which were sometimes found to be small and with low viability and greater dormancy, though not significantly so, no consistent differences were found between the viability and dormancy of grains in different positions in the ear.     

Candidate gene association with summer dormancy in tall fescue

Two main types of summer dormancy in tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] are recognized, eco-dormancy and endo-dormancy. Endo-dormancy is a physiological response to environmental signals leading to slowing of metabolic activity in meristematic tissues and most likely controlled by circadian clock genes. Therefore, it is genetically inherited and allelic variation among and between summer-dormant and non-dormant varieties is expected. The main objective of this study was to explore the association between dormancy and various candidate genes. Twenty-three genes were amplified and sequenced in two dormant and two non-dormant checks. Nucleotide variants unique to each group were converted to kompetitive allele specific PCR markers and were tested on 52 dormant and non-dormant accessions. Five markers, from the genes CONSTANS and TERMINAL FLOWER showed significant associations (R² = 0.10 to 0.13, p < 0.05) with field phenotypic scores. These two genes are known to modulate meristem determinacy and growth, suggesting that meristem determinacy is probably one of the mechanisms involved in summer dormancy in tall fescue. Another five markers showed significant associations with the surrogate germination phenotype (R² = 0.13 to 0.20, p < 0.05). One marker originated from dormancy-associated MADS-box gene sequence, three markers originated from auxin response factors sequences, and one marker was derived from heat shock proteins sequences. These results confirm the implication of photoperiod and temperature in the regulation of summer dormancy. A selection index combining these markers may be valuable for the differentiation between dormant and non-dormant tall fescue genotypes.     

楠木种子休眠与萌发特性的研究

为了解决育苗过程中楠木种子的休眠问题,对楠木种子的休眠和萌发特性进行了研究,结果表明:楠木种子的发芽抑制物质主要存在于除外种皮以外的其余部分,层积将使种子中的发芽抑制物质含量逐渐降低,抑制作用减弱,常温层积效果更明显,常温层积90d能完全解除楠木种子的休眠,发芽率可达80%以上;恒温25℃和变温30℃(日)/15℃(夜),萌发速度最快,发芽势和发芽率分别可达到45.5%和85.0%以上。     

Genetic relationships between preharvest sprouting and dormancy in barley

Preharvest sprouting (PHS) and dormancy (DOR) can be problems in barley production and end use quality, especially for barley used for seed and malting. Three crosses previously analyzed for DOR inheritance, were reanalyzed for PHS and DOR inheritance using artificial rain to calculate sprout score (SSc) and measure alpha-amylase activity (AA). Germination percentage of untreated grain for DOR was also measured. The crosses are ‘Steptoe’/’Morex’ (previously published), ‘Harrington’/TR306, and ‘Triumph’/Morex. Among the three crosses, DOR QTLs were located to six and PHS QTLs to five chromosomes, respectively. Chromosome 6H was never implicated. Previously identified DOR QTLs were confirmed in each cross, and most PHS QTLs coincided with DOR QTLs, but not all. Unique PHS QTLs were identified on chromosomes 1H (AA), 2H (SSc, AA), 3H (SSc, AA), and 7H (SSc, AA) and unique DOR QTLs on 1H, 2H, and 7H. Results indicate that PHS susceptibility and DOR are not always represented by opposite alleles at a locus. Some QTL regions for a given trait are conserved across crosses and some are not. Several QTLs are suitable for marker-assisted selection to balance PHS and DOR in breeding new cultivars.