多效唑和缩节胺对现蕾前忍冬枝叶生长及花蕾性状和有效成分含量的影响

以忍冬品种‘九丰一号’(Lonicera japonica‘Jiufeng 1’)为实验材料,采用叶面喷施方法研究了不同质量浓度多效唑和缩节胺对现蕾前(抽枝生长初期)枝叶生长和叶片叶绿素含量以及花蕾性状和花蕾中绿原酸和总黄酮含量的影响。结果显示:分别喷施100、400、700和1 000 mg·L-1多效唑和50、100、150和200 mg·L-1缩节胺后,多数处理组的开花枝条数、着花节数和叶绿素含量较对照CK1(水)有不同程度提高,但叶面积差异不明显。随处理时间延长,各处理组枝条节间长度总体上呈逐渐增加的趋势,其中多数处理组枝条节间长度增长缓慢。各处理的花蕾长度、百蕾鲜质量和干质量总体上小于CK1,而花蕾折干率、总黄酮含量和绿原酸含量显著或不显著高于CK1。此外,在喷施多效唑和缩节胺的同时喷施质量体积分数1.0%尿素和质量体积分数0.1%硼砂,忍冬的叶面积、着花节数、花蕾长度、折干率、百蕾鲜质量和干质量总体上有所提高,而绿原酸含量降低,但各指标的差异总体较小。研究结果表明:喷施适量多效唑和缩节胺可调控忍冬枝条生长,并能提高花蕾中总黄酮和绿原酸含量。     

秋水仙素诱导月季品种‘月月粉’2n花粉的研究

为获得二倍体古老月季品种‘月月粉’人工诱导2n花粉用于现代月季杂交育种,该研究在了解‘月月粉’花粉母细胞发育过程的基础上,使用秋水仙素注射结合包裹法处理幼嫩花蕾,成功获得了可正常萌发的2n花粉,并通过观察诱导获得的花粉离体及其在雌蕊上的萌发特征,初步评估2n花粉用于杂交育种的性能。结果表明:(1)秋水仙素药棉包裹造成部分花蕾在采粉前死亡,花蕾存活率随秋水仙素浓度提高和处理时间延长均极显著降低。(2)2n花粉诱导率在秋水仙素浓度为2.5、5.0、7.5和10.0 g/L间存在显著差异,但在处理时间为24、48和72 h间无显著差异;最佳诱导处理为5.0 g/L秋水仙素处理24 h,诱导率可达15.83%,该处理获得的2n花粉经亚历山大染色检验活力为27.2%。(3)‘月月粉’花粉母细胞在减数分裂时存在异常落后染色体和平行纺锤体,在四分体时期形成染色体数目加倍的二分体和三分体,最终产生2n花粉。(4)所诱导的2n花粉的体外萌发率和花粉管长度与天然花粉无显著差异,且都可以在母本柱头上萌发并长出花粉管进入子房,表明可用于进一步的杂交育种。     

种皮和播种深度对辽东栎种子萌发和幼苗早期生长的影响

在玻璃温室内遮荫条件下,研究种皮和播种深度(0、2、5、10和15 cm)对辽东栎种子萌发和幼苗早期生长的影响.结果表明:种皮对辽东栎种子萌发具有明显的抑制作用,去除种皮后,种子萌发率显著升高,不同播种深度处理种子萌发率平均升高19.4%,且萌发指数和活力指数显著增大,萌发进程加快.去皮种子和非去皮种子的萌发率均在2 cm播种深度下最大,分别为78.9%和62.2%;萌发指数和活力指数均在2 cm播种深度下最大,而萌发速率系数在5 cm播种深度下最大.去皮处理幼苗的单株叶面积和干质量与非去皮处理相比均显著增大,但比根长显著减小.去皮和非去皮处理幼苗株高均在5 cm播种深度下最大,分别为13.8和14.2 cm;基径随播种深度增加逐渐增大,而主根长、侧根数和最大侧根长均减小;幼苗干质量受播种深度影响较小.     

不同温度下PEG-6000模拟干旱对柠条锦鸡儿种子萌发的胁迫效应

在人工气候箱控制的不同温度(10、15、20、25℃和30℃)下,设置聚乙二醇(PEG-6000)质量百分比浓度分别为0%、5%、10%、15%、20%、25%和30%的7个模拟干旱胁迫处理,研究了柠条锦鸡儿(Caragana korshinskii Kom.)种子的萌发特性。结果表明:(1)温度和PEG模拟干旱胁迫及二者的交互作用对柠条锦鸡儿种子的萌发率、萌发速率系数、萌发值、萌发指数和活力指数均具有极显著影响(P0.01)。(2)种子萌发率在15℃下最大,显著大于10℃下的(P0.01),随着温度的继续升高逐渐减小;萌发速率系数随着温度的升高有减小的趋势,30℃下又显著增大;萌发值和萌发指数分别在25℃和20℃下最大,但均随温度的继续升高而显著减小(P0.05);活力指数随着温度的升高而减小,除在10℃和20℃间无显著差异外,其他温度间均差异显著(P0.05)。(3)种子萌发率、萌发值和萌发指数在15℃下与PEG浓度呈不显著的负相关关系,而在其他温度下均与PEG胁迫浓度显著负相关(P0.05),且相关系数均在25℃或30℃下最大;萌发速率系数在各温度下均与PEG胁迫浓度显著正相关;活力指数与PEG胁迫浓度呈显著负相关,相关系数随着温度的升高逐渐增大。(4)萌发参数与PEG胁迫浓度间的回归模型表现为三次曲线、二次曲线和直线模型3种类型,其中以三次曲线模型为主,全部回归模型均达到显著性水平(P0.05);在20℃以下的温度条件下,较低浓度PEG处理对柠条锦鸡儿种子萌发具有一定的促进作用,在15℃下种子萌发对PEG模拟干旱胁迫的耐受性最强;柠条锦鸡儿种子在不同温度和干旱胁迫下的萌发模式是对其分布区生境长期适应和进化的结果。     

赤霉素及萌发密度对戟叶酸模种子萌发的影响

利用种子萌发获得子代样品确定子代基因型以衡量适合度时,需要最大程度地提高种子萌发率,降低早期近交衰退对适合度估计的影响。以戟叶酸模(Rumex hastatus D. Don)种子为研究对象,设置3种萌发密度和有、无赤霉素处理的全交互实验,采用广义线性模型和双因素方差分析研究赤霉素和萌发密度对种子萌发率、出土子叶长度、首粒种子萌发时间和半数种子萌发时间4个指标的影响。结果表明,这4个指标在不同萌发密度情况下均无显著差异;赤霉素处理并未影响种子萌发率和首粒种子萌发时间,但经赤霉素处理后,出土子叶长度显著增大,半数种子萌发时间显著推迟。     

温度及盐胁迫对地梢瓜种子萌发及抗氧化酶活性的影响

以地梢瓜种子为试料,研究不同温度(5~45℃)及不同浓度NaCl胁迫(0~300mmol·L~(-1))对种子萌发及其抗氧化酶活性的影响。结果表明:(1)随着温度升高,种子各萌发指标呈先升高后降低的趋势,过高或过低均显著抑制种子正常萌发,萌发最适温度为25℃,在5℃和35℃条件下种子恢复萌发率均达95%以上。(2)随着NaCl浓度升高,种子萌发率、萌发势、活力指数呈显著下降趋势,而其相对盐害率呈增加趋势,且在300mmol·L~(-1)NaCl时萌发受到完全抑制;种子根系活力仅在高浓度NaCl(150mmol·L~(-1))下受到显著抑制;种子在解除盐胁迫后可一定程度恢复萌发,但最终依然受到盐胁迫的显著抑制,且盐浓度越高抑制越严重,其耐盐适宜浓度为65.25mmol·L~(-1)。(3)种子萌发率与盐胁迫下POD、APX活性呈显著正相关关系,而与相应O_2~生成速率、MDA含量呈显著负相关关系;种子活力指数与盐胁迫下CAT活性呈显著负相关关系。研究发现,地梢瓜种子萌发受到NaCl胁迫的显著抑制,保护酶POD与APX在盐胁迫种子萌发过程中发挥着主要抗氧化作用;地梢瓜适于在中度盐渍土中萌发生长。     

大花蕙兰四倍体的离体诱导和鉴定

采用组织培养方法研究了秋水仙素处理对大花蕙兰类原球茎增殖、分化和四倍体诱导的效应.结果表明,秋水仙素处理明显抑制类原球茎的增殖和分化,提高类原球茎褐变率和死亡率;在试验浓度和时间范围内,秋水仙素浓度越高,处理时间越长,抑制作用越强,解除抑制作用所需的继代次数越多.所有秋水仙素处理均能诱导出四倍体,但不同处理的四倍体诱导率不同,当处理浓度为0.05%、时间为5 d时,四倍体诱导率最高,为23.7%.二倍体及其四倍体的气孔保卫细胞长度和气孔密度均存在极显著的差异.四倍体植株比二倍体矮,茎部较粗壮,株型紧凑,叶片颜色浓绿、质地变硬.秋水仙素处理和组织培养相结合是创建大花蕙兰多倍体的有效方法.     

沙枣和柠条种子萌发期耐盐性研究

采用室内控制实验的方法,系统研究了沙枣和柠条种子萌发、生长、活力以及生理过程;对萌发、生长及活力指标与盐胁迫进行相关与回归分析,发现了实验室条件下沙枣和柠条种子萌发期的耐盐临界值;对生理指标与盐胁迫,生理指标与相应的萌发及生长指标进行相关性分析,在生理水平对沙枣和柠条种子萌发期对盐胁迫的响应进行了解释。主要结果包括：(1)胚根相对干重含水量与盐胁迫无相关性,初始萌发时间、休眠率以及死亡率与盐胁迫呈显著正相关,其它指标均与盐胁迫呈显著负相关;(2)胚根相对干重含水量与萌发种子初期生长无相关性,休眠率、死亡率与萌发率呈显著负相关,其它指标均与初期生长呈显著正相关;(3)受盐胁迫的抑制程度：萌发速度>萌发启动>萌发率;胚根生长>胚轴生长>萌发率;(4)种子萌发期,沙枣耐盐性强于柠条,两者耐盐临界值均高于0.1 mol·L^-1。     

光照条件对麻类作物发育影响的初步研究

1.从三种洋麻品种对不同光照长度反应的结果,说明洋麻在短日照条件下发育显著加速;“塔什干”在短日照及上海自然日照下植株转向发育均较早,“普通洋麻”“嫁接洋麻”在短日照下发育最快,三个品种在长光照下植株发育均显著延缓。 2.洋麻植株在经过一定短日照的天数处理后,即可显著提早现蕾,亦即完成光照阶段。但是现蕾後如无适当的光照条件仍不能继续开花。植株在开花後如移入不适合的光照条件下,则植株不能继续现蕾开花而上部植株乃继续营养生长,这可能与这种植株自下而上向顶的不断开花习性有关。     

短季棉早熟性的遗传效应及其与环境互作研究

以熟期不同的9个棉花品种为亲本,按部分双列杂交配制46个组合的F1、F2,在3个不同生态环境条件下,研究了7个早熟相关性状的遗传效应及其与环境互作。结果表明:短季棉7个早熟相关性状的遗传均以加性效应为主,同时存在着显性效应,对于播种-现蕾、播种-开花和现蕾-开花还存在着上位性效应;短季棉各早熟性状的遗传效应与环境互作显著。生育期、播种-开花的狭义遗传率均较高,分别为66.1%和49.1%,且与环境互作效应较小,而果枝始节和播种-现蕾的遗传率最低,分别为19.8%和18.8%,且与环境互作达到极显著水平,现蕾-开花、开花-吐絮和株高这3个性状的遗传率及其与环境互作居中。由此说明:早熟性的遗传受环境影响较大,在生态条件差异较大的育种地点,以果枝始节和播种-现蕾作为早熟性指标进行异地选择是不可靠的,而以生育期、开花期为早熟性选择指标是比较可行的。     

Dual effect of light on flowering and sprouting of rose shoots

Shade, caused by a dense leaf canopy in the light conditions of a normal greenhouse, reduced sprouting of the third axillary bud (from the top) on decapitated rose branches ( Rosa hybrida cv. Marimba) in comparison to less shaded buds on branches protruding above the canopy and sparsely spaced. Flowering of the third young shoot on shaded branches bearing 3 lateral shoots was totally inhibited. Mixed fluorescent and incandescent light in a growth chamber reduced sprouting of the third bud on decapitated rose branches in comparison to decapitated branches on rose plants held in fluorescent light of similar photon flux density. This was attributed to the higher R:FR ratio in fluorescent vs mixed light that reached the third bud, and in exposed vs shaded branches. Flowering of the third shoot was promoted by several factors: high photon flux density, 0.5 m M gibberellic acid (GA) or 0.2 m M benzyladenine (BA). BA was the most effective treatment. Treatments promoting flowering of the third shoot did not reduce growth or flowering of the upper shoots. However, spraying the uppermost shoot with BA suppressed the growth of the shoots below. It is concluded that light affects flowering in two ways. The effect on bud sprouting is related mainly to R:FR ratios, while the effect on flower development is related mainly to photon flux density. Cytokinins may substitute for the light effect on flower development.     

Basipetal Gradient of Axillary Bud Inhibition Along a Rose (Rosa hybridaL.) Stem: Growth Potential of Primary Buds and their Two Most Basal Secondary Buds as Affected by Position and Age

InRosa hybridaL. cv. Ruidriko ‘Vivaldi’®, theeffect of position on growth and development potentials of axillarybuds was investigated by single internode cuttings excised alongthe floral stem and its bearing shoot. The experiments werecarried out in both glasshouses and in a phytotron. The studyfirstly concerned the development of the primary shoot fromthe onset of bud growth until anthesis. The primary shoot wasthen bent horizontally to promote the growth of the two mostproximal secondary buds, the collateral buds, already differentiatedinside the primary bud. They gave rise to basal shoots. In thebasipetal direction, the axillary buds along the floral stemexhibited both an increase in the lag time before bud growthand a decrease in bud growth percentage, demonstrating the existenceof a physiological basipetal gradient of inhibition intrinsicto the buds or due to short range correlations. The same basipetalgradient of inhibition was observed along the floral stem andits bearing shoot, demonstrating that the age of the bud wasnot a major factor in determining the rate of bud growth. Afterbending the primary shoot, the percentage of collateral budgrowth was also affected by the cutting position. The more proximalthe cutting, the lower the sprouting ability of collateral buds.The growth potential of these buds appeared to be already determinedinside the main bud before cutting excision.Copyright 1998 Annalsof Botany Company Axillary bud; basal shoot; cutting; development; endodormancy; growth; paradormancy; position; primary shoot;Rosa hybridaL.; rose; secondary bud; topophysis.     

The inhibitory effect of gibberellic acid on flowering in Citrus

The application of gibberellic acid (GA₃) at any time from early November until bud sprouting, resulted in a significant inhibition of flowering in the sweet orange [ C. sinensis (L.) Osbeck] and the Satsuma ( C. unshiu Marc.) and Clementine ( C. reticulata Blanco) mandarins. Two response peaks were evident: the first occurred when the application was timed to the translocation of an unknown flowering signal from the leaves to the buds. The second occurred during bud sprouting, at the time the flower primordia were differentiating. From the pattern of flowering, it appears that the mechanism of inhibition was similar irrespective of the timing of GA₃ application. There was an initial reduction in bud sprouting affecting selectively those buds originating leafless inflorescences. An additional inhibition resulted in a reduction in the number of leafy inflorescences with an increase in the number of vegetative shoots, suggesting the reversion of a floral to a vegetative apex. The inhibited buds sprouted readily in vitro but invariably vegetative shoots were formed. A continuous influence of the sustaining branch is necessary to keep the flowering commitment of the buds; irreversible commitment occurs when the petal primordia are well differentiated.     

Influence des corrélations entre organes sur la croissance et le développement floral des bourgeons cotylédonaires chez leScrofularia arguta Sol.

The importance of various correlative influences on growth and vegetative or floral development of cotyledonary buds inScrofularia arguta Sol. is shown. The terminal bud, on the one hand, inhibits growth of cotyledonary buds and, on the other hand, induces their early flowering. The cotyledon stimulates growth of its axillary bud, but has no action on its floral development. Leaves above the cotyledonary node have the same effect as the cotyledon. Finally, roots stimulate vegetative growth of cotyledonary buds and suppress floral expression, but only when apical dominance has been removed at an early stage of development.     

Inhibition of flowering in vivo by existing fruits and applied growth regulators in Citrus unshiu

In the Satsuma mandarin ( Citrus unshiu Marc.) the presence of the fruit results in a gradual inhibition of flowering and of bud sprouting. This inhibitory effect starts several months before the onset of the winter rest period and lasts until the end of the accumulation of carotenoids in the fruit peel, more than one month after the completion of fruit growth. During all this time and until natural bud sprouting, flowering and bud sprouting are inhibited by exogenous gibberellic acid. Peak responses to this growth regulator coincide with periods of maximal rates of flowering inhibition by the fruit. Kinetin and abscisic acid, applied at the time of peak response to gibberellic acid, inhibited flowering and reduced the number of shoots developed through the reduction of the number of shoots formed per sprouted node, but failed to reduce the number of nodes which sprouted. The same pattern of sprouting was obtained in trees treated with gibberellic acid during the winter rest period or several months earlier. It is concluded that some step leading to flowering and which determines the differences in sensitivity of the buds to this growth regulator has taken place already at this early date.     

Growth and Dormancy Cycles in Citrus Bud Cultures and Their Hormonal Control

An in vitro bud culture method was devised in order to better understand the control mechanism of Citrus bud development. This technique offers a new approach to the study of hormonal control of growth, dormancy and flowering cycles in perennial plants. Buds were excised from orchard trees throughout the year, cultured on defined media for prolonged periods, and their vegetative growth responses to various growth hormones were determined. The buds proceeded with their vegetative development in vitro and achieved sprouting on a basal medium. The various growth regulators affected both the time required for sprouting (TRS) and the type of growth. In summer buds, IAA delayed sprouting, while GA enhanced it and caused shoot elongation. Cytokinins specifically induced the formation of numerous adventitious buds, whereas ABA completely inhibited sprouting; this inhibition, however, was reversible. A marked decrease in total protein and in the rate of its synthesis was evident during the first 20 days of sprouting induction and early bud growth. The annual growth rhythm was determined in spring buds sampled and cultured throughout the year, and an innate dormancy of citrus buds was revealed. Both the dormancy and the sprouting periods of buds in vitro corresponded to the natural periods occurring under field conditions. The effect of exogenous IAA, GA and cytokinins on the TRS varied at different periods along the season, suggesting the concept of “critical levels” in the endogenous balance of hormones.     

The bud and root sprouting capacity of Alternanthera philoxeroides after over-wintering on sediments of a drained canal

Alternanthera philoxeroides (Mart.) Griseb. is one of many aggressive invasive plants that can grow in diverse habitats. Aquatic A. philoxeroides forms dense floating mats over the water surface. However, when water levels decrease during winter, some mats become stranded on exposed sediments and are thus exposed to air. Do the stems of these mats possess the capacity to develop new shoots during the next growing season? In this study, we examined the sprouting of sediment-stranded over-wintering mats of A. philoxeroides. Stems of the over-wintering mats were divided into three types (dry, withered, and fresh stems) depending on moisture content and were immersed in water for 4 weeks to observe the sprouting of axillary buds and roots. The results showed that withered stems yielded much more biomass than dry or fresh stems. Stem moisture content significantly affected the sprouting rate and the length growth rate of buds and roots. Dry stems lacked reproductive capacity. The sprouting rate and length growth rate of the buds and roots were higher in fresh stems than in withered stems. Furthermore, the mean values of the bud sprouting rate and the bud length growth rate were highest during the first week, i.e., most of buds sprouted within 1 week or less. Our results suggest that more than 70% (on a dry weight basis) of the stems in stranded mats possessed rapid sprouting capacity even after over-wintering on the sediment for more than 2 months. This strategy may be an adaptation to the fluctuations inherent in many aquatic habitats, and it possibly explains why A. philoxeroides can flourish even after a dry winter. Handling editor: S. M. Thomaz     

Florigen is involved in axillary bud development at multiple stages in Arabidopsis

The wide variety of plant architectures is largely based on diverse and flexible modes of axillary shoot development. In Arabidopsis, floral transition (flowering) stimulates axillary bud development. The mechanism that links flowering and axillary bud development is, however, largely unknown. We recently showed that FLOWERING LOCUS T (FT) protein, which acts as florigen, promotes the phase transition of axillary meristems, whereas BRANCHED1 (BRC1) antagonizes the florigen action in axillary buds. Here, we present evidences for another possible role of florigen in axillary bud development. Ectopic overexpression of FT or another florigen gene TWIN SISTER OF FT (TSF) with LEAFY (LFY) induces ectopic buds at cotyledonary axils, confirming the previous proposal that these genes are involved in formation of axillary buds. Taken together with our previous report that florigen promotes axillary shoot elongation, we propose that florigen regulates axillary bud development at multiple stages to coordinate it with flowering in Arabidopsis.     

Revisiting the fate of buds: size and position drive bud mortality and bursting in two coexisting Mediterranean Quercus species with contrasting leaf habit

Understanding the relationships between bud size and position and bud fate through time is crucial for identifying and subsequently modeling the mechanisms underlying tree architecture. However, there is a lack of information on how bud size drives crown architectural patterns in coexisting tree species. We studied bud demography in two coexisting Mediterranean oak species with contrasting leaf habit (Quercus ilex, evergreen; Q. faginea, deciduous). The main objective was to analyse the effect of bud size on the fate of buds with different positions along the shoot (apical, leaf axillary and scale-cataphyll axillary buds). The number, length and position of all buds and stems were recorded in marked branches during 4 years. Study species presented different strategies in bud production and lifespan. The evergreen species showed greater mortality rate than the deciduous one, which produced larger buds. Bud size and position were highly related since apical buds where longer than axillary ones and bud length declined basipetally along the stem. Apical buds had also higher chances of bursting than axillary ones. Within positions, longer buds presented a higher probability of bursting than shorter ones, although no absolute size threshold was found below which bud bursting was impaired. In Q. ilex, four-year-old buds were still viable and able to burst, whereas in Q. faginea practically all buds burst in their first year or died soon after. Such different bud longevities may indicate contrasting strategies in primary growth between both species. Q. ilex is able to accumulate viable buds for several ages, whereas Q. faginea seems to rely on the production of large current-year buds with high bursting probability under favourable environmental conditions.