The influence of fruiting on the bud sprouting and flower induction responses to chilling in Citrus

Summary

The effect of chilling temperatures on bud sprouting and flower formation was compared on fruiting and non-fruiting ‘Owari’ satsuma mandarin (Citrus unshiu Marc) trees. On non-fruiting trees, bud dormancy was weak, and a significant proportion of buds were able to sprout at high temperatures without being chilled. Separate effects of low temperatures on bud sprouting and flower induction were demonstrated. On fruiting trees these two effects of low temperatures were also demonstrated on summer-flush buds, but not on older (spring-flush) buds. The spring-flush buds from fruiting trees scarcely sprouted without being chilled. These buds required a longer chilling period for dormancy release than for flower induction, and it was not possible to separate the effect of low temperature on flower induction from the effect on dormancy release. The presence of fruit reduced flower formation by reducing bud sprouting. Furthermore, fruit had a direct inhibitive effect on vernalization which resulted in increased formation of vegetative shoots. The effect of fruit and low temperature on flowering was unrelated to carbohydrate accumulation in the leaves or the roots.     

The effect of chilling,defoliation and hydrogen cyanamide on dormancy release,bud break and fruiting of Anna apple cultivar

The effect of defoliation (DEF) alone or combined with hydrogen cyanamide (HC) on dormancy state, fruit quality and yield of Anna apple cultivar was studied. Trees were manually defoliated on three successive dates, November 15th, December 1st and December 15th. The flower buds (FB) entered the endodormancy synchronized with vegetative buds (VB) for most of the treatments. Most of the treatments terminated endodormancy between January 27th and February 8th during the season 2004/2005 and between January 18th and February 8th during the season 2005/2006. The treatments were effective in dormancy release of FB and somewhat with VB. Defoliation on November 15th + HC recorded the lowest chilling accumulation needed to reach 50% bud break. All the treatments exceeded the control considering the percentage of flower (FBB) and vegetative bud break (VBB) either in the lab or at the field. Growing degree hours and the number of days required to reach each stage of fruiting were differed between the two studied seasons. The control and DEF on December 15th exceeded all the treatments regarding initial fruit set percentage (IFS). The defoliation treatments alone gave the highest yield (kg/tree). Defoliation + HC treatments gave the best fruit quality, while the control gave the least values.     

Effects of shading and thidiazuron + oil treatment on dormancy breaking,blooming and fruit set in apricot in a warm-winter climate

Overcoming dormancy represents one of the major limitations to fruit tree production in warm areas. High temperatures during the chilling period have a negative effect on breaking of dormancy. Shading of trees reduces the incidence of radiation and the temperature. Previous works on shading did not take into account the stage of dormancy. The aim of this work was to evaluate the effects of shading during different periods of endodormancy, in an area having relatively warm winters, and the effects of a treatment of thidiazuron ([TDZ] N-phenyl-N-1,2,3-thiodiazol-5-il-urea) and winter oil, on apricot blooming, fruit set and ripening. The study was carried out during three years which showed marked differences regarding chilling accumulation. Autumn shading did not affect blooming or harvesting. Regarding harvest date, 2–3 days of precocity were achieved by shading during endodormancy, relative to the control. The TDZ + oil treatment increased blooming percentage, made blooming more uniform and brought forward the blooming (by 7–14 days) and ripening (3–8 days) dates. However, pistil abortion percentage was strongly increased by using TDZ and winter oil when there was low chilling accumulation, which led to reduce fruit set percentage. Shading during late endodormancy produced 5 days precocity for the harvest date in the year with lower chill accumulation. Shading of trees during endodormancy and TDZ + oil treatment could be suitable for increasing precocity in warm-winter climates. Significant year-to-year variation has been shown for blooming, pistil abortion, fruit set and fruit/bud percentages. Correlations among these variables are also discussed. Under conditions of marginal chill accumulation, the distribution of chilling during autumn and winter had an important role in the overcoming of dormancy, blooming and fruit set.     

梨两个休眠相关MADS-box 基因特征及在其休眠过程中的表达分析

 PpMADS1 和PpMADS2 是从‘酥梨’（Pyrus pyrifolia white pear group‘Suli’）休眠芽转录组 文库筛选的两个与休眠相关的MADS-box 基因序列。为了解序列的特征,对其进行了相关生物信息学分 析,并以‘翠冠’和‘圆黄’梨为试材,用实时定量PCR 技术分析其花芽休眠不同阶段的表达变化。结 果表明：两个基因都具有MADS-box 家族的特征序列MIKC-基序,PpMADS1 和PpMADS2 分别与日本梨 （P. pyrifolia‘Kosui’）休眠相关的两个MADS-box 基因PpMADS13-1 和PpMADS13-2 聚在一起,且单独 聚为一支,与李属植物休眠相关的MADS-box 基因关系最近。在两个品种的休眠过程中,PpMADS1 和 PpMADS2 的表达呈现相似的变化趋势,都有一个表达高峰,但‘翠冠’梨PpMADS1 和PpMADS2 的表 达高峰均出现在11 月15 日,而‘圆黄’梨PpMADS1 的表达高峰延后到12 月30 日,PpMADS2 的表达 高峰出现在12 月15 日。两个品种PpMADS1 和PpMADS2 的表达高峰都出现在内休眠解除之前,随内休 眠解除其表达量下调,在生态休眠阶段表达量维持在较低的水平。据此推测PpMADS1 和PpMADS2 的表 达对梨芽内休眠的解除具有调控作用     

几种落叶果树H2O2含量变化与自然休眠关系的研究

 以设施栽培中常见的几种核果类果树品种和两个葡萄品种为试材, 分析了芽休眠期间 H₂O₂含量变化动态, 并探讨了温度、生长调节剂及化学破眠物质对H₂O₂含量影响的效应。结果表明: 休眠期间,不同树种( 品种) 芽内 H₂O₂含量存在差异, 基本趋势是晚熟品种高于早熟品种, 花芽高于叶芽, 但葡萄品种相反, 早熟的‘京秀’高于晚熟的‘巨峰’; 休眠期芽内 H₂O₂含量基本呈稳步上升后急剧下降的趋势,不同品种急剧下降的时间略有差别, 且与自然休眠解除的时间相吻合。低温(5 ℃) 处理显著增加了芽中 H₂O₂含量, 中温(10 ℃) 使 H₂O₂含量略有增加, 而高温(20 ℃) 却导致 H₂O₂含量降低。休眠前期50 mg.L^-1 ABA 处理显著提高了芽中H₂O₂含量, 而100 mg.L^-1的GA₃和6-BA 处理有减少 H₂O₂含量的趋势, 但二者差异不明显。热带地区常用的化学破眠物质对芽 H₂O₂的影响因树种( 品种) 、使用时期不同而异, 硫脲、KNO₃前期使用对核果类果树影响明显, CaCN₂对核果类无明显效应, 但对葡萄品种作用显著。果树芽 H₂O₂含量的动态变化表明, H₂O₂可能是低温解除自然休眠的原因。     

H_2O_2在外源GA_4解除果梅季节性休眠中的信号作用

以GA_4处理的果梅休眠芽和转PmRGL2基因杨树叶片为材料,通过测定H_2O_2含量、抗氧化酶类活性及其编码基因和信号转导相关基因表达的变化,分析了H_2O_2在外源GA_4解除果梅休眠中的信号作用。结果表明:GA_4处理的果梅花芽的萌芽率显著高于对照,且H_2O_2含量在休眠解除时达到峰值,信号转导相关基因表达发生规律性变化;‘桃形梅’和‘丰后’的需冷量分别为574 CH(低温小时数Chilling hours)和1 108 CH,休眠解除前后,两品种叶芽中的H_2O_2含量没有显著差异,但需冷量低的‘桃形梅’具有更高的抗氧化酶类活性;转Pm RGL2杨树中NADPHoxi下调表达,有利于使H_2O_2含量维持在较低水平,并对赤霉素合成及信号转导相关基因的表达产生影响,而抗氧化酶类活性及其编码基因的表达量上升。推测GA_4通过调控抗氧化酶类活性而影响H_2O_2含量的变化,并引起上下游多种信号相关基因表达水平的变化,最终对休眠解除起作用。     

温度对甜樱桃花芽酚类物质含量和相关酶活性及休眠的影响

以7年生甜樱桃红灯(PrunusaviumL.cv.Hongdeng)带有花芽的离体枝条为试材,研究了不同温度对红灯花芽酚类物质含量、相关酶活性及萌芽率的影响。结果表明,不同温度处理对酚类物质含量影响效果不同,自然休眠前期低温(5℃)减缓了酚类物质的积累,中期提前达到其高峰并进入下降阶段,后期加速其降低;高温(20℃)则效果相反,变温(5℃/20℃)的效果不明显。自然休眠的不同时期,不同的温度处理对PAL和PPO活性的影响效果也不相同,低温(5℃)在休眠前期抑制PAL活性的增长而提高了PPO活性,中期使PAL活性迅速降低的同时却加速了PPO活性的升高;后期降低了PAL活性,提高了PPO活性。高温(20℃)的作用效果与低温(5℃)相反。变温(5℃/20℃)对PAL和PPO活性的影响效果不明显。低温(5℃)在自然休眠的3个阶段都能打破休眠促进萌发;高温(20℃)抑制了花芽的萌发;变温(5℃/20℃)对花芽的萌发影响不大。     

Cold and heat requirements of the apricot tree (Prunus armeniaca L.)

Summary

The cold units (CU) and heat units (HU) required for the flowering of 13 apricot cultivars (Prunus armeniaca L.) cultivated in AbaraÂn (Murcia) have been established. The end of the dormancy period was determined on the basis of the dry-weight increase of the flower buds. The tests in which the dry weight was measured after forcing the flower buds at 208C turned out to be more precise in detecting the beginning of the reactivation phase than those in which they were not forced.     

几种适宜设施栽培果树需冷量的研究

 1996～1999 年, 采用Utah 加权模型, 先后对5 个树种、65 个常见设施栽培果树品种的需冷量及相关特性进行了研究。结果表明: 不同树种、品种的需冷量差异显著, 葡萄、西洋樱桃的需冷量最高, 桃最低, 李、杏居中, 而且年际间有较大差异, 说明作为一种遗传特性, 需冷量亦受环境因素的调节; 同一树种不同品种的需冷量高低与本品种果实的成熟期无明显关系, 果实成熟期早而需冷量较高的情况普遍存在; 同一品种其需冷量基本趋势是花芽高于叶芽; 根系在低温需求进程中起调控作用, 与地上低温同步的根际高温减少了花芽的需冷量, 而根系低温则没有效果。晚秋根外喷布6-BA 降低了油桃和杏的低温需求量, GA₃ 则有增加低温需求量的趋势, 而ABA 无明显效果。     

剥鳞和化学药剂处理对甜樱桃花芽休眠及酚类物质的影响

  以7年生甜樱桃‘红灯’和‘早红宝石’为试材, 分析了自然休眠期间剥鳞和化学药剂处理对酚类物质含量及对休眠解除的影响。结果发现, 休眠花芽中的酚类物质主要分布于鳞片中, 剥鳞后, 花芽中酚类物质含量锐减。自然休眠的不同时期剥鳞对打破休眠的效果不同, 前期效果较为明显, 中期处于休眠的最深时期, 剥鳞不能打破休眠, 后期剥鳞也能打破休眠促进萌发。不同化学药剂在休眠的不同时期对酚类物质含量的影响不同: 自然休眠前期, KNO₃ 和硫脲减缓了酚类物质的积累速度, 相反H₂O₂ 加速了酚类物质的积累; 中期上述3种化学药剂对酚类物质含量的影响与早期相似; 后期KNO₃ 处理降低了酚类物质含量, 硫脲使酚类物质含量略有增加, 而H₂O₂ 使之显著增加。在打破休眠方面, KNO₃ 可提前2～3 d打破休眠, 硫脲没有明显效果, H₂O₂ 反而抑制休眠的解除。     

Effect of artificial chilling on the depth of endodormancy and vegetative and flower budbreak of peach and nectarine cultivars using excised shoots

Stem cuttings were obtained from 12 peach and nectarine cultivars during leaf fall, placed in plastic bags at 3.0 ± 0.1 °C to simulate 0–800 h of chilling and forced to budbreak at 20.0 ± 1.0 °C for a period of 6 weeks. Some cultivars showed high blooming and leafing without exposure to chilling; chilling enhances leafing and blooming but the percentage increment was higher in leaf buds. In general, maximum budbreak was reached with less chilling accumulation (<100–200 h) in flower buds compared with leaf buds; excessive chilling caused a reduction of the percentage budbreak in flower but not in leaf buds. Additionally, chilling modified the proportion of blooming that occurred before leafing. In non-chilled shoots, blooming occurred earlier than leafing, except in cv. ‘San Pedro 16–33’ but the proportion of blooming before leafing decreased significantly with chilling in most cases. By studying the mean time to budbreak, we conclude that the flower bud generally has a lower intensity of rest; the intensity of rest declines at a slower rate in flower than in leaf buds with chilling; flower buds had greater heat requirements than leaf buds when the chilling requirement had been covered, so that each peach cultivar had a point of critical chilling accumulation below which blooming tended to occur earlier, and above which leafing tends to occur first. Flower and leaf buds had different depths of endodormancy but similar chilling requirements in the majority of peach and nectarine cultivars studied. Finally, different varieties with similar chilling requirements showed different responses to chilling. Therefore, the cutting test measuring the response of vegetative and floral buds provides considerable information on the characterisation of the variety, compared with the sole and traditional data of chilling requirements.     

Effects of pre-blossom temperatures on flower development and fruit set in apricot

The influence of pre-blossom temperatures on flower development and fruit set is ascertained in apricot (Prunus armeniaca L.), a species without previous records on the effect of pre-blossom temperature on fruit set, but that is particularly prone to erratic fruit set. A polyethylene cage was used during pre-blossom development of flower buds to increase maximum temperatures by 6–7 °C and mean temperatures by 3 °C in orchard conditions. This increase in temperature accelerated flower bud development, caused a hastening in flowering time and following hand-pollination, reduced fruit set. At anthesis, flowers that had developed in warmer conditions weighed less and showed less development of the pistil than control flowers. Pistil growth of flowers under warm conditions did not differ from that of the control flowers when both the populations were compared on a real time scale in spite of the fact that warmed buds were at an advanced external phenological stage. Thus, hastening of external floral development by warm pre-blossom temperatures was not accompanied by advance in pistil development. This lack of synchrony resulted in premature flowering of flowers with underdeveloped pistils that had a reduced capability to set fruit. The results are discussed in terms of flower quality and its implications in fruit set and subsequent crop load.     

梨花芽休眠相关miRNA的鉴定和差异表达分析

为了探究梨花芽休眠进程中miRNA的表达模式和靶基因,利用Solexa测序技术、生物信息学分析和实时荧光定量PCR（qPCR）技术,对内休眠、内休眠解除和生态休眠解除3个时期梨花芽的miRNA进行高通量测序、筛选和鉴定。结果表明,内休眠、内休眠解除和生态休眠解除时期3个样本文库中分别有12 276 226、10 135 952、11 453 981条Unique序列。miRNA主要分布在21 ~ 24 nt之间,其中长度为24 nt的数量最多。共检测到151个已知的miRNA,属于39个不同的家族,并利用生物信息学软件预测到了209个新的miRNAs。比较分析从内休眠进入到生态休眠解除的整个休眠转换时期差异表达的miRNA,筛选出8个miRNA（ahy-miR156b-5p、cpa-miR319、aly-miR172c-3p、aau-miR396、mdm-miR858、aly-miR171b-3p、bdi-miR160f和hbr-miR166a）,其靶基因主要参与转录调控、信号传导等过程。利用qPCR验证了8个miRNA及其8个靶基因的表达。     

油桃开花时间调控基因在花芽休眠过程中的表达分析

对拟南芥中21个调控开花时间的基因进行NCBI blast比对后找到桃中所对应的同源基因,以拟南芥的突变体表型及基因注释功能为依据分为促进开花和抑制开花两类。以7年生‘曙光’油桃花芽为试材,利用水培法测定萌芽率,界定休眠分为诱导期、自然休眠期和休眠解除期3个阶段。研究结果表明诱导期和自然休眠期内花芽单芽质量上升平缓,休眠解除后突然升高到0.12 g,翌年2月9日达到0.15 g;而花芽含水量从诱导期开始缓慢下降,在休眠解除时达到最低水平（39%）,之后平稳上升到53%。聚类分析发现,两类基因对开花的影响与其在休眠进程中的表达趋势不存在必然的相关性。利用荧光定量PCR（RT-PCR）技术测定目的基因在休眠过程中的表达特性,发现在休眠进程（自然休眠和休眠解除期）中PpFT-like和PpCO-like表达量逐渐升高,推测其可能与需冷量积累相关。PpDDL-like、PpCCT-like、PpELF8-like、PpAMP1-like、PpHUA2-like和PpHUB1-like表达量先升高后降低,在休眠解除时达到最高水平之后随休眠解除下降,与花芽休眠解除进程一致,推测其可能参与调控花芽休眠解除过程。     

仁用杏花芽3个发育时期数字基因表达谱分析

以仁用杏‘优一’为试材,运用转录组、数字基因表达谱技术,研究了仁用杏花芽萌动期前后相关基因的表达规律。结果发现,仁用杏花芽在花芽萌动期前后进行着各种旺盛的生物合成和代谢活动,且4个开花调控途径（光周期途径、春化途径、自主途径、GA调控途径）均已启动,光周期途径在花芽萌动时发挥重要作用,涉及到了74条基因,其中有38条差异基因上调表达,29条下调表达;GA途径在花芽萌动期对花芽的生长发育调控表现为抑制作用,涉及到了60条基因,其中有13条差异基因上调,9条差异基因下调;其他两条途径于花芽萌动前作用,其中春化途径涉及到了23个基因,其中有4条差异基因上调,15条差异基因下调;自主途径涉及到了24条基因,其中有3条差异基因上调,11条差异基因下调。本研究通过数字基因表达谱分析,初步了解仁用杏花芽萌动前后的网络途径,为后期对仁用杏花芽相关开花基因的研究、探明仁用杏早花的分子机理及通过分子育种方法培育仁用杏晚花品种提供坚实的理论依据。     

几种化学药剂对破除葡萄与桃自然休眠的效果

以桃、葡萄为试材,探讨多种化学药剂和外源生长调节剂打破休眠的效应。结果表明:CaCN2打破葡萄的休眠效果稳定,可使萌芽提早6～17d,并提高萌芽率,其破眠效果随需冷量的增加而显著;几种化学药剂在桃树上应用,其打破休眠的效果差异较大,CaCN2、NH4NO3对打破桃休眠无效,硫脲的破眠效果最明显,可使叶芽萌发提前9～12d、花芽6d,并提高萌芽率;KNO3对破除休眠亦有一定效果。外源生长调节剂对休眠的调节作用因调节剂种类、浓度和使用时间而异:Ze(50mg/L)+GA3(100mg/L)可完全打破叶芽的休眠,100mg/L6-BA对尚未完成自然休眠的花芽萌发有明显的促进作用,IAA和2,4-D却对芽的萌发表现出强烈的抑制作用。     

影响南京甜樱桃坐果的关键时期

研究不同生育期的生态条件对甜樱桃花芽分化和坐果的影响,确定导致南京地区（年均温 > 15 ℃）甜樱桃坐果率低的关键时期,将郑州的一部分4年生盆栽结果甜樱桃运至南京生长1年后,然后将郑州和南京两地的盆栽苗分别在落叶期、休眠结束后进行双向位置交换,采用石蜡切片法观察花芽和胚囊形态发育,并在果实着色期观察坐果率。结果显示：全生育期在郑州、落叶期由郑州运至南京、休眠结束后由郑州运至南京、全生育期在南京、落叶后由南京运至郑州的‘早红宝石’甜樱桃坐果率分别为38.2%、14.7%、12.9%、8.9%和31.7%;无胚囊的比例分别为41.5%、55.6%、57.7%、74.5%和50.0%;全生育期在郑州和落叶后由郑州运至南京休眠结束后再运回郑州的甜樱桃‘萨米脱’的坐果率分别为13.9%和18.8%。结果表明：影响南京地区甜樱桃坐果的关键时期应是春季开花坐果期;而对于一些能满足需冷量的品种,休眠期对坐果率的影响不大;夏季花芽分化期的高温影响花芽分化进程及分化质量。