甘蔗光周期诱导开花和杂交利用研究

本文报道了１９９８年度云南甘蔗研究所光周期诱导甘蔗开花及杂交利用结果，本研究以４月１日和６月１日两种起始处理时间，１２ｈ２５ｍｉｎ和１２ｈ１５ｍｉｎ两种固定日长处理，于１０月１日起到日递减光３０ｓ至抽穗时止的光周期诱导技术分别对７个难花亲本和７个常用亲本进行了开花诱导。结果表明，在不同的光周期处理下，粤糖５７／４２３，Ｃｏ４１９，闽糖７０／６１１，罗汉蔗等４个难花亲本被诱导开花，７个常用亲本全部孕     

短日照在光敏核不育水稻幼穗发育中的作用探讨

短日（ＳＤ）、长日（ＬＤ）和不同天数的短、长日照处理光敏核不育水稻１０５Ｓ 和对照常规品种１０５。ＬＤ处理的植株始终不分化，一直处于营养生长状态；而先经６，９或１２ ＳＤ诱导再经ＬＤ处理的植株，结果表明ＳＤ具有：诱导幼穗分化的作用；提高可育程度的作用， 但１０５Ｓ对ＳＤ提高可育程度的作用较不敏感，还具有加速幼穗发育进程、缩短生育期的作用。在 不同的光周期处理下，１０５Ｓ和１０５叶片的过氧化物酶同工酶及其酶活性均有差异，较突出的差异 在ＳＤ（９）叶片中，这与ＳＤ提高可育程度的作用有关．     

光周期对光温敏核不育小麦ES-8育性转换特性的影响

在人工控制光周期和控制光温条件下，研究了光周期和短日适温对光温敏核不育小麦ＥＳ－８育性转换特性的影响。结果表明，ＥＳ－８的雄性育性受光周期的影响，表现为１０～１１ｈ短光照下雄性不育，花粉败育率为１００．０％；自交结实率为０．０％；在１２～１３ｈ长光照下可育。ＥＳ－８存在两个光周期敏感期，最敏感期为雌雄蕊分化期至药隔形成期，次敏感期约在药隔形成期至四分体形成期。孕穗至结实期的短日（１０ｈ）适温（１６／１２℃昼温／夜温）处理结果表明，温度对育性的影响很小，雄性仍表现不育。     

湖北光敏感核不育水稻光敏感：期叶片中ATP含量与RuBPcase活力的分析

本文测定ＴＨＰＧＭＲ农垦 ５８Ｓ光敏感期叶片 ＡＴＰ含量和 ＲｕＢＰｃａｓｅ活力的变化。结果表明：（ １）当材料由暗期进入光期时， ＨＰＧＭＲ ５８Ｓ叶片中的ＡＴＰ含量在长日照下比短日照下低，而材料由光期进入暗期时则相反；对照品种农垦５８在长日和短日照下无明显差异；（ ２）ＨＰＧＭＲ ５８Ｓ叶片中的ＲｕＢＰｃａｓｅ活力在长日照下明显比短日照下低，而对照品种农垦５８差异很小。由此推测ＨＰＧＭＲ在不同日照条件下其代谢途径有所不同。     

大豆GmPic基因的分离及表达分析

对光敏感型大豆品种“中豆24”进行长日、短日和自然光3种光周期处理,采用cDNA-AFLP的方法筛选差异片段,并进一步通过RACE技术分离了该基因。该基因全长983 bp,包含一个完整的开放阅读框,编码248个氨基酸,在遗传关系上与线粒体磷酸盐转运蛋白高度同源。通过半定量RT-PCR对该基因在不同光周期中的表达模式进行分析,结果表明,该基因在大豆生长发育的早期阶段表达,短日照抑制其表达,而长日照则增强其表达。因此,大豆线粒体磷酸盐转运蛋白基因可能是作为一种负调控因子参与大豆光周期反应。对大豆线粒体磷酸盐转运蛋白基因的研究能为进一步阐明大豆光周期反应分子机理打下基础。     

光周期条件对湖北光敏感核不育水稻育性转变的影响

湖北光周期敏感核不育水稻是湖北省发现培育的新不育材料,其育性转变受日照长度所控制。本研究通过人工光照和自然日照的调控等手段,初步探明了诱导育性转变的光周期的临界光照长度、光周期阈光值、暗期连续性的作用等。并对曙、暮光在诱导育性转变中的作用进行了论述。     

大豆"短青春期"品种的光(温)反应研究Ⅲ.对长日照的反应

在分析“短青春期”品种对播季和短日照反应的基础上，本研究通过比较不同品种出苗至开花天数与开花成熟天数对长日处理的反应，以进一步明确夏大豆型“短青春期”品种的光（温）敏感性特征。研究结果表明：春播条件下，开花前16小时长光照使“短青春期”品种中豆24种丰的出苗至开花天数分别延长19天和30天，是供试品种类型中对长日照最敏感的类型；开花前长日照处理，开花至成熟天数两个“短青春期”品种间表现差异较大，中豆24有所延长，而巨丰则有所缩短，开花前短日 开花后长日处理，中豆24和巨丰的开花至成熟天数均较春大豆明显延长，但小于秋大豆，通过30天和60天的长日照处理可以发现，长日处理结束后，中豆24和巨丰植株需分别接受7-9天和15-18天的短光照，才能开花和进入结实期，中豆24出苗至开花天数在长日下的温度敏感度高于春大豆品种，而巨丰出苗至开花天数的温度敏感度极小。     

中国大豆不同生态类型代表品种开花前、开花后光周期反应的比较研究

选用中国大豆主要生态区的代表品种１２个,在南京（３２°Ｎ）春播,通过人工光照处理,比较了各类型品种开花前和开花后光周期反应敏感性的差异。结果表明,１２ｈ短光照处理使所有品种的开花期显著提前（Ｐ＜０．０１）;开花后进行短日照处理,使除早熟品种东农３６和泰兴黑豆以外的其它品种成熟期显著提前（Ｐ＜０．０１）。在本试验条件下,南方夏大豆品种开花后光周期反应比开花前更加敏感,其它类型品种开花前光周期反应比开花后敏感或前、后期敏感性接近。相关分析表明,大豆开花前和开花后的光周期反应敏感性,与自然光照下相应发育时期的长度正相关。较长的前期有利于单株粒数和单株产量的提高,较长的后期对提高百粒重有利。文中讨论了大豆品种开花前、开花后光周期反应敏感性与原产地日照长度及其它环境因子的关系。     

长日照对光周期敏感型大豆顶生花序发育的影响

顶生花序是识别大豆类型的重要组分,在本研究中,选用晚熟且对光周期敏感的大豆,研究长日照对此大豆顶生花序形成和发育的影响。出苗后,大豆幼苗经12h短日照,光周期13d,以便诱导顶生花序的开始。然后,把植株     

Real-time PCR检测大豆CONSTANS基因在不同光照条件下的表达

采用实时荧光定量PCR方法检测了不同感光大豆品种的CO(CONSTANS) 基因在不同光照条件下的mRNA水平变化.结果表明:早熟品种东农49和晚熟品种东农42各自在短日照(8h/16h 光/暗)下会比长日照(16 h/8 h 光/暗)下表达有所增强,同时东农49中CO基因的表达要高于东农42,它们的表达峰值均出现在光暗交界处.东农42由长日照或短日照移入完全光或完全暗条件时,暗下CO基因的表达量剧增,并且大致维持之前长日照和短日照的表达规律.CO基因的表达有很强的昼夜节律性,暗下利于其表达,并且在不同感光品种中表达有所不同.     

Light and genotype effects on in vitro tuberization of potato plantlets

Summary In vitro tuberization responses of eleven clones of potato were evaluated under different photoperiods and light intensities. No growth regulators were added to the medium to avoid the potential modification of the response to the environmental stimuli. Plantlets were grown on MS medium containing 3% sucrose for four weeks under long days (16 h). Tuberization was induced by short days (8 h). Five photoperiodic combinations and three light intensity treatments were applied. Light applied after the tuber induction phase delayed or inhibited tuber initiation (at proper photoperiods both at 111 and 55 μmol m⁻² s⁻¹ light intensities at 24/15 °C day/night temperature). Darkness following the induction stage accelerated and synchronized tuber initiation after high light intensity. However, these effects of dark treatment depended on light intensity applied in short days before dark treatment. There was an interaction between the duration of darkness applied in photoperiodic treatments and the light intensity applied in short days on tuber initiation. No relationship was observed between the maturity groups of clones tested and their tuber initiation responses. Tight interaction (P≤0.01) of treatments and clones was proved by statistical analysis. Reliable tuberization and high rate of tuberization (1.20–1.52) can be reached using these hormon-free systems.     

Use of jasmonate for conditioning of potato plantlets and microtubers in greenhouse production of minitubers

A two-year study was conducted to determine the effects of (1) jasmonic acid (JA) pre-treatment, (2) JA supplement in culture media, (3) cultivar (Amisk, Atlantic, Russet Burbank, Shepody, and Umatilla Russet), (4) light (0 h, 8 h), and (5) dormancy breaking treatment (Rindite, gibberellic acid) on greenhouse production of minitubers from microtubers andin vitro plantlets. The microtubers were produced under short day (8 h) light conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on tuberization media with or without JA.In vitro plantlets (the industry choice in nuclear seed potato production) of all five cultivars performed well, meeting the standard criteria for greenhouse production of minitubers. Production of minitubers from microtuber-derived plants of cvs Amisk, Russet Burbank, and Umatilla Russet was similar to that of plantlet-derived plants with regard to number of minitubers. Yields (weight), however, were lower than those from plantlets. Microtuber responses to JA varied with cultivar. Amisk produced the highest number of minitubers per plot from microtubers derived from JA pre-treated plantlets. Jasmonic acid-pretreated microtubers also gave significantly more minitubers in Russet Burbank and Umatilla Russet than the microtubers from other treatments. Shepody did not benefit from JA treatments and JA pre-treated Atlantic microtubers performed poorly, producing significantly lower yields of minitubers than other cultivars. Independently of cultivar, microtubers produced under 8-h photoperiod gave significantly higher yields of minitubers than microtubers produced in the dark. Dormancy release was the key factor influencing microtuber performance. Rindite proved to be a much more effective dormancy breaking treatment than gibberellin. JA conditioning of stock plants prior to tuberization is being proposed as a treatment in production of microtubers for greenhouse production of minitubers.     

Change in Some Glycoalkaloids of Potato under Different Storage Regimes

The potato (Solanum tuberosum L.) is an important food crop worldwide. Potato tubers can be stored to provide continuity of supply between production seasons, but it is important that they be stored under appropriate conditions as incorrect storage will result in deterioration in end user quality and may increase glycoalkaloid levels. We have investigated the effects of types of household storage on potato glycoalkaloid content (total glycoalkaloids [TGA]; α-solanine; α-chaconine) in Turkey. Tubers of potato cultivars (cvs.) Agria and Bettina were stored under four types of storage conditions (indirect sunlight for 10 h per day and dark storage for the remaining 14 h per day; storage under continuous fluorescent light; storage in constant darkness; storage in the dark in a refrigerator) for 56 days. Samples of tubers were taken at the beginning of the storage period and after 14, 28 and 56 days of storage for tuber glycoalkaloid measurement. Tubers stored in the three light environments showed an increase in glycoalkaloid levels; however, none of the cv. Agria tubers reached the critical level of 200 mg/kg tuber. On day 56 the TGA level of cv. Bettina tubers stored under fluorescent light reached 234.31 mg/kg.     

Variability and regulation of the number of ovules, seeds and pods according to assimilate availability in winter oilseed rape (Brassica napus L.)

The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse. The objectives of this study were to investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability.Field experiments were conducted with the variety Mendel. Different trophic states were created by clipping the main stem or ramifications. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season.On the control plants, for the main stem we observed that the number of ovules per pod decreased for a few ranks and then tended to increase and again to decrease at the end. On ramification R1 and R4, the number of ovules increased at first, and then remained constant with the pod rank. Furthermore, the number of ovules per pod remained constant along the inflorescence on the other ramifications and increased with ramifications from top to bottom. The number of seeds per pod did not vary with the pod rank at the basal positions on inflorescences and decreased afterwards along the inflorescence. The clipping of the main stem or ramifications increased the number of ovules per pod, seeds per pod and pods per axis. The number of ovules and seeds per pod did not vary with the time of pod appearance for the pods located at normalised rank 0.01-0.1. However, the number of ovules and seeds per pod can be impacted by the time of pod appearance on the plant scale. Thus, our results indicate that the amount of available assimilates was the primary determinant of pod and seed production during the flowering period. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant.     

Seed production in white clover (Trifolium repens L.). II. Effect of autumn defoliation on potential seed yield and seed yield components

A field experiment was conducted to assess the effect of autumn defoliation treatments on inflorescence production, potential seed yield and yield components of white clover cv Makibashiro. Between 10 July and 10 October 1992, white clover swards were subjected to one of three treatments: monthly cutting to 3–4 cm (4DEF), cutting to 3–4 cm on 10 August and 10 October (2DEF), and no cutting (control). The total numbers of inflorescences and the proportion of inflorescences in different development categories were counted throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. There were consistent significant differences in inflorescence density between treatments. Plots which received the 2DEF treatment produced significantly more inflorescences than did the no-defoliation (control) and 4DEF-treatment plots. In this particular year the optimum harvest date (date at which the proportion of ripe inflorescences and potential seed yield was highest) was 26 July, approximately 30 d after peak flowering. Defoliation treatments had no effect on optimum harvest date. However, treatments differed in potential seed yield and ripe inflorescences on this date. The 2DEF treatment gave the highest potential seed yield because there were significantly more ripe inflorescences than either the contol or 4DEF plots. Control plots produced inflorescences with more florets than the other two defoliation treatments, but the differences were not always significant. Seed number per pod was higher in inflorescences obtained from previously defoliated plots than from control plots. The 1000-seed weight was significantly lower in inflorescences developed in 4DEF plots than those developed in 2DEF and control plots. The results are discussed in relation to the management of white clover seed crops and the importance of canopy structure and light intensity for seed production.     

Absence of a serum melatonin rhythm under acutely extended darkness in the horse

Background  

In contrast to studies showing gradual adaptation of melatonin (MT) rhythms to an advanced photoperiod in humans and rodents, we previously demonstrated that equine MT rhythms complete a 6-h light/dark (LD) phase advance on the first post-shift day. This suggested the possibility that melatonin secretion in the horse may be more strongly light-driven as opposed to endogenously rhythmic and light entrained. The present study investigates whether equine melatonin is endogenously rhythmic in extended darkness (DD).     

Manipulation of microtubers for direct field utilization in seed production

A two-year field study was conducted to determine the effects of jasmonic acid (JA), light (duringin vitro explant production andin vitro tuberization phases), and dormancy-breaking treatment on performance of microtubers in the production of seed tubers (pre-elite) in five potato cultivars. Microtubers were produced under short day (8-h) conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on tuberization media with or without JA. Microtuber performance was compared to invitro plantlets transplanted directly to the field. Yields of tubers from microtubers were 30% to 40% of those from plantlets. Microtubers of cultivars Amisk and Russet Burbank produced the highest yields of pre-elite tubers. Atlantic microtubers performed poorly in the field. JA pre-treatment of stock plantlets, prior toin vitro tuberization, enhanced seeds tuber production from microtubers in Russet Burbank and lowered in Shepody. JA presence in media duringin vitro tuberization significantly lowered production of tubers while exposure to 8-h light resulted in microtubers performing significantly better in the field than microtubers produced in the dark. Dormancy release was the key factor influencing microtuber performance. Unlike greenhouse studies, gibberellic acid (GA₃) was more effective than Rindite. A further refinement of the production and handling methods is required before microtubers can be recommended for field production of seed tubers.     

Phase delaying the human circadian clock with a single light pulse and moderate delay of the sleep/dark episode: no influence of iris color

Background  

Light exposure in the late evening and nighttime and a delay of the sleep/dark episode can phase delay the circadian clock. This study assessed the size of the phase delay produced by a single light pulse combined with a moderate delay of the sleep/dark episode for one day. Because iris color or race has been reported to influence light-induced melatonin suppression, and we have recently reported racial differences in free-running circadian period and circadian phase shifting in response to light pulses, we also tested for differences in the magnitude of the phase delay in subjects with blue and brown irises.     

马铃薯试管块茎形成机制的研究——暗处理与光照时间对试管块茎形成的影响

试验采用“Mira”、“87P48—64“两个栽培品种的脱毒苗为材料,在培养温度20℃、诱导温度-18℃条件下,小苗生长4周后,采用不同天数黑暗处理诱导,再分别转入长日照和短日照条件下培养8周,观察统计不同处理的试管块茎形成能力.试验结果表明,黑暗处理和短日照条件对试管块茎的形成是有利的.试验中以黑暗处理两天,每天光照8小时的处理单株结薯总数最多.