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1.
This study was conducted to elucidate the function of leaves and their role in the alteration of plant hormone homeostasis during potassium chlorate (KClO3) induced “off season” floral induction (FI) of longan. KClO3 application had almost no effect on the concentration of gibberellins in receptive apical and lateral shoot meristems, whereas the auxin IAA initially decreased, but later remarkably increased. The most significant changes caused by KClO3 treatments was an increase in zeatin/zeatin-riboside (Z/ZR) type cytokinins (CKs) 8 days after treatment in the shoot apical and close by lateral buds as well as in the tissue beneath these buds. The 6–7-fold increase in CK concentrations were greatly reduced in the absence of leaves (leaves removed between the apical bud and a girdle). A significant exception was a strong accumulation of isopentenyl adenine/isopentenyl adenosine (iP/iPA) type CKs in wood and bark beneath the bud of defoliated shoots that were isolated against the rest of functional leaves of the tree by a girdle. This accumulation of iP/iPA, the immediate precursors of Z/ZR, together with the strong increase of Z/ZR in the shoot apical bud (SAB) after KClO3 application indicate that leaves may be involved in the biosynthesis of CKs. Overall, the results suggest that cytokinins play a significant role in KClO3 induced “off season” floral induction in longan. This role may not be restricted to the biosynthesis of these hormones but also to their mobilization and accumulation in the SAB of newly flushing shoots.  相似文献   

2.
Previous experiments demonstrated that treatment of longan trees with potassium chlorate (KClO3) induces “off season floral induction” (FI) even in the absence of the naturally required cool temperature [Manochai, P., Sruamsiri, P., Wiriya-alongkorn, W., Naphrom, D., Hegele, M., Bangerth, F., 2005. Year around off season flower induction in longan (Dimocarpus longan, Lour.) trees by KClO3 applications: potentials and problems. Sci. Hortic. 104, 379–390]. Potassium chlorate, however, cannot replace the presence of functional mature leaves and sufficient light intensity. Here we examined in more detail the effect of shade (about 10% of natural sunlight) on KClO3 affected hormone concentrations/transport of leaves and shoot apical buds (SAB) and their interactions with FI.  相似文献   

3.
Dendrobium nobile Lindl. is a popular temperate Chinese orchid commonly marketed as a traditional medicinal plant. Seedlings of Dendrobium nobile Lindl. produced floral buds (33.3–34.8%) precociously on a defined basal medium (1/2 MS) containing paclobutrazol (PP333) at 0.5 mg L−1 or thidiazuron (TDZ) at 0.1 mg L−1 within 4 months of culturing. The frequency of floral buds formation can be further increased to 95.6% by growing seedlings in a PN (PP333 0.3 mg L−1 + NAA 0.5 mg L−1)-containing medium followed by transfer onto 1/2 MS medium with PP333 and TDZ (PP333 + TDZ). However, flower developed was deformed under 25 °C but it developed fully when grown in a lower temperature regime (23 °C/18 °C, light/dark) for 45 days. Under optimal condition, in vitro flowering was observed about 6 months after seed sowing.  相似文献   

4.
《Scientia Horticulturae》2002,92(2):125-135
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.  相似文献   

5.
The involvement of carbohydrates, water potential, cell wall components and cell wall-based enzymes in regulating flower development in Dendrobium crumenatum was investigated. Plants were subjected to cold treatment to release floral buds from dormancy, and the various parameters were investigated from young floral bud stage till flower senescence. Development of floral buds was accompanied by progressive decrease in concentrations of fructans and starch. Upon full flower opening, concentration of soluble sugars was maximum, accompanied by a more negative water potential. High pectin methylesterase activity was observed during early bud development and decreased thereafter. Significant increase in activities of β-galactosidase, β-mannosidase and β-xylosidase was also observed during floral bud development. The cell walls of sepals and petals were modified extensively during floral bud and flower development, as observed by changes in the amounts of celluloses, hemicelluloses and total pectin. Pectin solubilisation was also observed to commence during early floral bud development. These results indicated that carbohydrate hydrolysis, osmotic changes and cell wall dissolution that began early in young floral buds, all regulated flower development in this sympodial orchid. Possible applications of the findings in the horticultural industry are discussed.  相似文献   

6.
Mango flowering is an important physiological event that sets the start of fruit production. Initiation is the first event that takes place for mangoes to flower. Coincident with shoot initiation, induction occurs based on the conditions present at the time of initiation. Numerous studies with mango trees support the existence of a florigenic promoter (FP) that is continuously synthesized in mango leaves and induces flowering. Translocation experiments suggest that the FP is carried from leaves to buds in phloem. Induction appears to be governed by the interaction of the FP and a vegetative promoter (VP). The FP is translocated as far as 100 cm in subtropical conditions and 52 cm in tropical conditions. In the tropics, floral induction occurs in stems that have attained sufficient time in rest since the previous flush. The age of the last flush is the primary factor governing flowering in the tropics as evidenced by experiments in Colombia. Tip pruning is ideal to synchronize vegetative flush events in the canopy. Potassium nitrate (KNO3) has been shown to stimulate flowering in sufficiently mature stems. Tip pruning and foliar applied KNO3 are effective methodologies that induce synchronous flowering especially in Colombia. Cool temperatures are important for mango floral induction under subtropical conditions. Mangoes grown in the low-latitude tropics rely less on low temperature. Soil and leaf analyses should be conducted to evaluate the nutrient status of trees.  相似文献   

7.
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8.
The application of gibberellic acid (GA3) to the whole loquat tree from mid-May to early June and from early August to the onset of flowering, significantly reduced the number of premature flowering shoots per current shoot and per m3 of canopy, and so reduced the total number of panicles per m3 of canopy. The number of vegetative shoots per m3 of canopy was also significantly reduced by applying GA3. The response depended on the concentration applied and produced optimal results at 50 mg l−1. Differences in the number of flowers per panicle and leaves per shoot were not significantly modified by the treatment. Nevertheless, GA3 applied directly to the developing apex near to flower differentiation reduced the number of flowers per panicle by 25–35% and without modifying the morphological characteristics of the panicle. Results suggest that less sprouting of lateral buds was largely responsible for the reduction in flowering intensity caused by GA3. Best treatments reduced thinning costs (60%, approximately) of premature flowering shoots, slightly increased fruit diameter and significantly improved fruit colour and juice quality, thus advancing harvest date.  相似文献   

9.
《Scientia Horticulturae》2002,95(3):261-268
Selection of suitable production locations in Australia and New Zealand for production of myoga (Zingiber mioga Roscoe) has been limited by lack of information on climatic influences on flowering. This study focused on photoperiod as potential production sites within Australia differ considerably in daylength due to the geographical range. The two cultivars available in Australia (Inferior and Superior) were examined in this trial due to previously observed differences in vegetative and reproductive development.Plants grown under long-day conditions (16 h) and short-day conditions (8 h) with a night break produced flower buds, while those under short-day conditions (8 h) did not. The failure of plants under short-day conditions to produce flower buds was due to abortion of developing floral primordia rather than a failure to initiate inflorescences. It was concluded that for flower development in myoga a qualitative long-day requirement must be satisfied, but that flower initiation was day-neutral.Short-day conditions resulted in abortion of flower primordia, premature senescence of foliage and reduced foliage dry weight in both cultivars. Early senescence and low flower bud yield of the Inferior cultivar, but not the Superior cultivar have been observed in crop evaluation trials in Southern Australia and New Zealand. Differences in critical photoperiod between the two cultivars may explain this observation and therefore photoperiodic requirements may be an important consideration in site and planting date selection for different cultivars.  相似文献   

10.
Knowledge of the factors involved, and tools to control morphology and flowering are important in intensive and cost-efficient greenhouse production. Hydrangea macrophylla is an important flowering pot plant in Norway and is produced year-around in greenhouses. Due to problems in scheduling, a study was conducted to compare floral transition and morphology of two commercially important cultivars of Hydrangea (‘Early Blue’ and ‘Schneeball’) under different flower initiating treatments in growth chambers. Plants were grown with high pressure sodium lamps (HPS) at moderate temperature (17 °C) (MT) and high (24 °C) temperature. At high temperature, the effect of (1) irradiance under long day conditions (16 h lighting with 70 or 200 μmol m−2 s−1), and (2) short day (8 h lighting) was investigated. The short day treatment had similar light integral as the low irradiance long day treatment (SD: 8 h × 140 μmol m−2 s−1 and LD: 16 h × 70 μmol m−2 s−1 = 4.0 mol m−2 d−1). The intention was to test the effect of irradiance and SD on flower transition and morphology under high temperatures. The results clearly showed that MT is the strongest signal for floral transition. MT resulted in a rapid floral transition of the terminal buds and lateral flower buds. A short forcing period was required and the plants became short and compact without any use of chemical growth retardants. At high temperatures only SD had a promotive effect on flower transition and the response was found to be stronger in ‘Schneeball’ than ‘Early Blue’. In general, all the treatments under high temperatures required a long forcing time and the plants tended to be very tall with a low number of lateral flower buds.  相似文献   

11.
《Scientia Horticulturae》2005,103(4):441-451
The aim of the study was to examine the effects of different photoperiod and light integral on floral initiation, development and subsequent growth of Eustoma grandiflorum (Raf.) Shinn. Six-weeks-old seedlings of ‘Echo Blue’ and ‘Fuji Deep Blue’ were placed under short day (SD, 10 h) and were transferred to long days (LD, 20 h) at 2-week intervals from 6 to 14 weeks after seeding. Plants initiated flower buds regardless of light regimes. Flower bud initiation was delayed by SD compared to LD; plants transferred after 6 weeks from seeding initiated flower buds at least 21 and 10 days earlier at LD at high (HL) and low (LL) daily light integral, respectively, compared to those at SD. Light regimes had little or no effect on time to flower bud development after initiation. Thus, it seems likely that LD and HL affected the initiation rather than development. Both the photoperiod and light integral strongly influenced the subsequent growth after initiation. SD delayed the time to visible bud (VB), increased the number of nodes to first open flower, number of branches, stem diameter and shoot dry weight compared to LD. HL promoted flowering and increased several shoot characteristics and flowering compared to LL.The results indicate that Eustoma is a quantitative long-day plant. LD, and more specifically HL, enhanced flower bud initiation, development and subsequent growth. An initial SD period is preferred to increase the number of branches, number of flowering buds and flowers, stem diameter and shoot dry weight.  相似文献   

12.
The application of gibberellic acid during flower bud induction significantly reduced flowering of ‘Black Diamond’ and ‘Black Gold’ Japanese plums. The response depended on the concentration applied and on the type of shoot. Mixed shoots had a similar response in both varieties, flowering being reduced by 40% for GA3 50 mg l−1 and by 75–90% for GA3 75 mg l−1 or higher concentration. With regard to spurs, GA3 50 mg l−1 reduced flowering intensity by 40% and 25% in ‘Black Gold’ and ‘Black Diamond’, respectively, and GA3 75 mg l−1 or higher concentration reduced flowering by 70% and 50%, respectively. This partial inhibition of flowering significantly reduced the cost of manual thinning. The best GA3 concentration was found to be 50 mg l−1, since it reduced the cost of thinning by 45–47% and increased final fruit weight by 7–33% for ‘Black Diamond’ and ‘Black Gold’, respectively. Not significant differences in yield and in mature fruit characteristics of treated trees were found compared to untreated trees.  相似文献   

13.
Nolina recurvata Hemsl. is a very decorative indoor plant but difficult to micropropagate vegetatively. In vitro cuttings failed to induce adventitious rooting. Investigations for a rapid micropropagation using β-cyclodextrin added to the rooting medium has solved the problem. Rooted N. recurvata plantlets were obtained after successive stages of various culture media.Initiation and in vitro multiplication of this plant was possible with lateral buds cultured in Murashige and Skoog medium supplemented with 4.45 μmol of BA and 0.5 μmol of IBA. The number of axillary shoots by explant obtained was 6.In vitro rooting was obtained in MS medium (1/2 strength of minerals salts) supplemented with β-cyclodextrin. This substance, at 1.76 mmol associated with 5 μmol of IBA, improved quality and the rooting rate by 100%.  相似文献   

14.
Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees was achieved in controlled greenhouse experiments by low temperature (LT) and by the application of potassium chlorate at high temperature (HT + KClO3) during two consecutive seasons. The latter treatment was successful also at temperatures above 20 °C. The present experiment was conducted to investigate possible alterations in the concentrations of plant hormones exerted by these two methods and to relate them to the floral induction process. The following hormones were examined by radioimmunoassay in the shoot apical buds (SAB), and in sub-apical bark and wood: the auxin indole-3-acetic acid (IAA); gibberellins (GAs); and the cytokinins zeatin/zeatin riboside (Z/ZR) and isopentenyl-adenine/isopentenyl-adenosine (iP/iPA).  相似文献   

15.
Brunonia australis R. Br (Goodeniaceae) and Calandrinia (Portulacaceae), native to Australia, are potential new flowering potted plants. This research investigated the role of daylength and growth regulators, Gibberellic acid (GA3) and paclobutrazol (Pac), to control vegetative growth, peduncle elongation and flowering of Brunonia and Calandrinia. Plants were grown under long days (16 h), short days (11 h) and 8 weeks under short day then transferred to long day (SDLDs). Plants in each daylength were treated with GA3, Pac, and GA3+ Pac. GA3 was applied as 10 μL drop of 500 mg L−1 concentration to the newest mature leaf. A single application of Pac was applied as a soil drench at 0.25 mg a.i. dose per plant. Both Brunonia and Calandrinia flowered earlier in long days but still flowered in short days, so both can be classified as facultative LD plants. Brunonia under SDLDs were more vigorous and attractive than plants under LDs while still being more compact than plants under SDs. In Brunonia, GA3 promoted earlier flowering and increased the number of inflorescences under SDs. Pac at 0.25 mg a.i. per plant applied alone or in combination with GA3 had extended flower development in Brunonia, and resulted in a reduced number of inflorescences per plant compared to the control plants. Vegetative growth of Calandrinia was similar under LDs, SDs and SDLDs, whereas GA3 application increased plant size. Pac-treated Calandrinia looked compact and attractive, and Pac application did not affect time to flower and flower number.  相似文献   

16.
Summary

Calamondin (× Citrofortunella mitis J. Ingram & H. E. Moore) is known for its ability to develop floral organs to flower in the adult phase during the four seasons. To provide information on molecular events during floral differentiation from axillary buds, we constructed a cDNA library from floral differentiating axillary buds of adult phase calamondin. Ninety-six cDNA clones were randomly selected from this library and sequenced. Ninety-six nonredundant ESTs were identified. Two clones encoded S-adenosylmethione decarboxylase, a key enzymes in polyamine biosynthesis. CmSAMDC 1 (Citrofortunella mitis s-adenosylmethionine decarboxylase 1) contained an 1083 bp ORF that encoded a putative SAMDC precursor of 361 amino acids. Northern blot analysis revealed that CmSAMDC 1 was expressed in axillary buds prior to floral differentiation and in axillary buds immediately after floral differentiation, in immature flower (5 mm), in fully developed flowers (120 mm long), in floral parts (petals, pistils, and stamens) of trees in the adult phase of development, but not in leaves or axillary buds of juvenile phase nucellar seedlings or leaf tissue from trees in adult phase of development. In situ hybridization revealed expression of the CmSAMDC 1 gene in the floral apex of axillary buds after differentiation, and in the phloem of axillary buds and petioles. These results suggest that SAMDC could play a role in actively differentiating and developing reproductive and vegetative organs.  相似文献   

17.
Flowering is generally considered to be advanced by water deficits in many woody perennial species. A long-standing paradigm being that as a plant senses severe environmental conditions resources are diverted away from vegetative growth and towards reproduction before death. It is demonstrated that in Rhododendron flowering is promoted under water deficit treatments. However, the promotion of flowering is not achieved via an increase in floral initiation, but through separate developmental responses. If regulated deficit irrigation (RDI) is imposed prior to the time of initiation, fewer vegetative nodes are formed before the apical meristems switch to floral initiation, and chronologically, floral initiation occurs earlier. Both RDI and partial rootzone drying (PRD) treatments stimulate the development of more flowers on each inflorescence if the treatments are continued after the plant has undergone floral initiation. However, floral initiation is inhibited by soil water deficits. If the soil water deficit continues beyond the stages of floral development then anthesis can occur prematurely on the fully formed floral buds without a need for a winter chilling treatment. It is hypothesised that inhibition of floral initiation in plants experiencing severe soil water deficits results from the inhibitory action of ABA transportation to the apical meristem from stressed roots. It is demonstrated that ABA applications to well-watered Rhododendron inhibit floral initiation.  相似文献   

18.
SUMMARY

The possibility of using water stress during floral initiation and development, to synchronize flowering in potted coffee trees of cvs Catuai Rojo and Mundo Novo was investigated. Moderate and severe cyclic and constant water stress had little effect on vegetative growth during floral initiation. However, upon rewatering, shoot growth was significantly greater in plants where leaf water potential [¨,] had declined to -2.5 MPa compared with plants where ¨, was maintained above -0.5 MPa. The period of floral initiation was not influenced by water stress and occurred only under short days (<12 h). In contrast, a y, of -2.5 MPa significantly reduced the number of inflorescences compared with plants maintained at a ¨| of -0.5 or -1.5 MPa. This reduction was associated with leaf drop in stressed plants. Therefore, regular irrigation during the period of floral initiation is recommended. Water stress (¨, of -1.5 or -2.5 MPa compared with -0.5 MPa) accelerated floral development with no deleterious effects on floral differentiation. Once flower buds are fully differentiated they enter dormancy and reach anthesis only if trees are stressed and rewa-tered. Flower buds remain dormant if trees are watered regularly or a constant water stress provided. A constant period of water stress in the late stages of floral development after floral initiation is complete provides a means of increasing the proportion of fully differentiated dormant flower buds (mature buds). This could represent a practical method to achieve synchronized flowering in field conditions where there is irrigation and a reliable dry season in the late stages of floral development.  相似文献   

19.
观赏海棠花色时序动态分布格局研究   总被引：1，自引：0，他引：1  
 采用X-Rite 色差计对97 个观赏海棠品种大蕾期（S1）、盛开期（S2）、末花期（S3）3 个阶 段的花色进行了测定,开展了品种群间的花色关系及时空分布规律研究,旨在为挖掘和创制海棠特异种 质和花色育种提供参考。采用Origin7.0 软件构建了观赏海棠品种群花色在CIELCH 色空间中的三维动态 分布图,结果表明：在开花进程中,各品种花色在L*（亮度）、C*（饱和度）和h*（色调角）三个维度皆 呈规律性空间分布特点和阶段性变化趋势,所有品种的L*值持续上升而C*值持续下降,L *值高而C *值低 的品种权重显著增加;在h *维度方向,h * 值呈增大趋势,分布在红色区域（h *值0 ~ 20°）的品种权重由大 蕾期的85.6%下降至末花期的52.6%,而分布在黄色区域（h *值90° ~ 110°）的品种权重由大蕾期的2.1% 上升到末花期的28.9%。采用SAS6.12 软件构建了花色聚类分析树状图,结果表明：在遗传距离2.17 和 1.69 处,97 个海棠品种可以划分为3 大色系和6 个子色系类群,即紫红色系（含紫红、暗紫红和灰紫红 3 个子色系）、粉色系（粉红和白粉2 个子色系）和白色系类群,色系/子色系类群之间具有明显不同的色 彩参数特征。3 大色系品种花色淡化程度及淡化快慢节律差异显著,在大蕾期-盛开期-末花期的开花进 程中,白色系品种呈现由紫红-白（或稍带粉）-白色先快后慢的节律快速淡化为白色,粉色系品种由 紫红-粉-淡粉（或近白色）匀速淡化,紫红色系品种（A3 除外）呈现由紫红-紫红-淡紫红先慢后快 的节律淡化,总淡化程度显著低于粉花色系。在6 个子色系中,色彩稳定性最强的是暗紫红子色系（A2） 和紫红子色系（A1-1）,始终保持较高的饱和度,而粉花子色系色彩稳定性则逊色得多。  相似文献   

20.
A perusal of literature showed that a little is known about the metabolic changes related to senescence in orchid flowers. It was observed that unpollinated flowers of Cymbidium pendulum (Roxb.) Sw. remained fresh for 20 days and senesced within 8 days after pollination (DAP), while that of Cymbidium aloifolium (L.) Sw. took 18 days when unpollinated but showed senescence in 7 DAP. A higher level of electrolyte leakage was recorded in all the floral organs of pollinated flowers in both the species. There was a concomitant increase in levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2); indicators of oxidative damage, in all the organs for both the species. Ascorbic acid, on the other hand, decreased significantly. Higher amount of electrolyte leakage, MDA and H2O2 content were recorded in C. pendulum as compared of the other species while the ascorbic acid, on the other hand, was observed to be decreased and this decrease was more in C. pendulum than C. aloifolium suggesting a higher oxidative damage to the floral organs in the former species than the latter. TIBA, i.e. tri-iodobenzoic acid (an auxin inhibitor; 0.25 μM) and silver nitrate (ethylene inhibitor; 0.25 μM) application to pollinated flowers partially prevented the elevation of oxidative damage and consequently senescence suggesting the involvement of these hormones in governing these changes in orchid flowers. Comparatively, AgNO3 was more effective than TIBA in delaying senescence.  相似文献   

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