Flower Development in Silene: Morphology and Sequence of Initiation of Primordia

The initiation and development of the flower of Silene coeli-rosawas followed by examining apices by scanning electron microscopy.The sepals, stamens and carpets are initiated in a spiral sequence,the direction of the spiral king the opposite of the acropetalhelix of unequal axillary buds at the nodes below the flower.The petals are initiated almost simultaneously and at the sametime as the first few stamens. The change in phyllotaxis fromopposite and decussate in the vegetative shoot to spiral inthe flower occurs with the displacement of the first two sepalsaway from the mid-line of the apex and towards the axillarybud at the node below the flower. The sizes of the sepals andstamens are a function of their age since initiation but thepetals grow more slowly. The Silene flower can be interpretedas a shoot bearing primordia with associated axillary primordia,some of the latter being precocious in their development. Silent weli-rosa, flower initiation, flower development, phyllotaxis, primordia     

Ovule and Embryo Sac Development in Malus pumila L. cv. Cox's Orange Pippin, from Dormancy to Blossom

Ovule and embryo sac development in the flowers of Cox's OrangePippin apple (Malus pumila L.) were studied from dormancy topetal fall using both scanning electron and light microscopy.The relative timing was established between these developmentsand the external development of the flower bud and flower. Malus pumila L. cv. Cox's Orange Pippin, apple, Cox, SEM, ovule development, anatomy, histology     

Density Studies on Lupins: I. Flower Development

In an August-sown experiment the pattern of flower developmentwas followed for cv. Ultra (Lupinus albus L.) and cv. Unicrop(L. angustifolius L.) grown at low (10 plants m^–2) andhigh (93 and 83 plants m^–2, Ultra and Unicrop respectively)densities. Dry weight increase of flowers on the main-stem inflorescenceand first lateral below the main-stem were compared at differentfloral stages. Maximum flower weight was reached just priorto the open flower stage and remained constant or declined untila pod formed or abscission occurred. The time period betweenmaximum flower weight and pod formation or abscission was upto 10 days. Emergence of the inflorescence was earlier and thefirst flower of Ultra opened 10 days before Unicrop. Developmentof each terminal raceme (inflorescence) was acropetal, withpods having formed on lower flower nodes when terminal flowerswere still quite immature. Laterals forming the next generationof inflorescences grew from axillary leaf buds below an inflorescencewhile it was in full flower. Sources of competition from connectedreproductive and vegetative metabolic sinks are discussed. Lupinus spp., lupins, flower development, planting density     

Photoperiodic Regulation of Flowering in Cowpeas (Vigna unguiculata (L.) Walp.)

To test the proposition that photoperiodic controls synchronizethe flowering of cowpeas, Vigna unguiculata (L.) Walp. [V. sinensis(L.) Savi], the day-length requirements for floral initiationand for flowering were investigated in several short-day accessions.No evidence was found of different critical photoperiods atdifferent stages of development, but exposure to only 2–4short days was required for floral initiation compared withabout 20 for development to open flowers. Pod setting was increasedafter exposure to even one short day more than the number requiredfor flower opening. Floral buds at higher nodes appeared to require fewer shortdays for development to flowering than buds at the lower nodes,and displayed faster rates of development. Inflorescence budsdid not resume development if they were exposed to 15 or morelong days following inflorescence initiation. Thus, any tendencytowards synchronous flowering in cowpeas is not due to the criticalday-length for flower development being shorter than that forflower initiation, but could be the result of cumulative photoperiodicinduction of plants and the more rapid development of later-formedflowers. Vigna unguiculata (L.) Walp., cowpeas, flower initiation, flower development, fruit set, photoperiodism     

The Rest Period of RhododendronFlower Buds I. EFFECT OF THE BUD SCALES ON THE ONSET AND DURATION OF REST

Shortly after flower differentiation, Rhododendron flower developmentis interrupted by a rest period. The results reported here showthat the onset and duration of rest depended upon the presenceof the flower bud scales. When the scales were removed beforethe onset of rest, the flowers continued to elongate and attainedanthesis. Intact buds stopped growing and remained in rest forat least four months. Scale removal after the onset of restterminated the rest period, though there was a lag phase beforethe flowers began to elongate. The duration of the lag phasewas related to the time of scale removal. The scales preventedflower development in situ, on detached stems and in vitro.Theresults further show that the rest period of each flower budwas independent of the rest period of adjacent flower buds andthat the resting terminal flower buds correlatively inhibitedthe growth of the lateral vegetative apices. The correlativeinhibition was eliminated by removing the terminal flower budor by breaking the rest period of the flower bud.     

Structural Aspects of the Neo-formation of Floral Buds on Leaf Discs of Streptocarpus nobilis Cultured in vitro

Leaf discs of Streptocarpus nobilis were cultured in vitro underconditions leading to flowering. The histo-logical aspects ofthe in vitro flower bud development were studied. It was foundthat in some instances flower buds develop from meristematiccells differentiated from wound tissue, and in others they arisedirectly from epidermal and sub-epidermal leaf blade tissues.     

Leaf and Flower Development in Pea (Pisum sativum L.): Mutants cochleata andunifoliata

The stipule mutant cochleata(coch) and the simple-leaf mutantunifoliata(uni) are utilized to increase understanding of the controlof compound leaf and flower development in pea. The phenotypeof the coch mutant, which affects the basal stipules of thepea leaf, is described in detail. Mutant coch flowers have supernumeraryorgans, abnormal fusing of flower parts, mosaic organs and partialmale and female sterility. The wild-type Coch gene is shownto have a role in inflorescence development, floral organ identityand in the positioning of leaf parts. Changes in meristem sizemay be related to changes in leaf morphology. In the coch mutant,stipule primordia are small and their development is retardedin comparison with that of the first leaflet primordia. Thediameter of the shoot apical meristem of the uni mutant is approx.25% less than that of its wild-type siblings. This is the firsttime that a significant difference in apical meristem size hasbeen observed in a pea leaf mutant. Genetic controls in thebasal part of the leaf are illustrated by interactions betweencoch and other mutants. The mutantcoch gene is shown to changestipules into a more ‘compound leaf-like’ identitywhich is not affected by thestipules reduced mutation. The interactionof coch and tendril-less(tl) genes reveals that the expressionof the wild-type Tl gene is reduced at the base of the leaf,supporting the theories of gradients of gene action. Copyright2001 Annals of Botany Company Pisum sativum, garden pea, leaf morphogenesis, compound leaf, leaf mutants, flower morphology     

Studies on the Glasshouse Carnation: Effects of Light and Temperature on the Growth and Development of the Flower

Experiments were concerned with the growth and development offlowers of carnation (Dianthus) var. White Sim from the timethe flower buds became visible up to anthesis. Rates of growthin size of the flower were decreased by either low temperaturesor low light intensities but only low temperatures caused anappreciable delay in anthesis. Effects of low light intensitycould be simulated by partial defoliation and appeared to bemediated through effects on photosynthesis. Temperature, however,acted directly on processes occurring in the flower bud. The rate of development of the flower, in the sense of progresstowards anthesis, appeared to be independent of levels of assimilatesavailable for growth. It is suggested that processes controllingdevelopment in the flower regulate the partition of assimilatesbetween the flower and the remainder of the shoot system. Seasonal variations in rates of flower development under glasshouseconditions are considered to be largely attributable to variationsin the temperature of the flower buds.     

Possible Roles of Methyl Glucoside andMyo-inositol in the Opening of Cut Rose Flowers

Methyl glucoside andmyo-inositol are present in all organs ofrose (Rosa hybridaL.). To investigate the possible role of thesecarbohydrates in the opening of cut roses, flowers with a 10,20 or 40-cm-long stem and a single flower bud (about 1.5 cmin diameter) were placed in water and flower opening and changesin sugar content in flowers and stems examined for 7 d. Thelonger the stem of the cut flower, the larger was the flowerdiameter. In stems, the concentration of carbohydrates, includingmethyl glucoside andmyo-inositol markedly decreased before floweropening. In petals, contents of glucose, methyl glucoside andmyo-inositolalso decreased before flower opening, but those of fructose,sucrose and xylose did not. When glucose and methyl glucosidewere added to the vase water (4%) flower opening was clearlypromoted; this was accompanied by an increase in methyl glucosideand fructose concentrations in petals. On the contrary,myo-inositolinhibited flower opening, and this was accompanied by an increaseinmyo-inositol and xylose concentrations in petals. These resultssuggest that methyl glucoside and/or its metabolites are transportedinto the petal cells, thereby lowering the osmotic water potentialand promoting flower opening.Myo-inositol is not readily metabolized,and exogenousmyo-inositol given at a high concentration mayact as an extracellular osmolyte, which inhibits water uptakeand flower opening.Copyright 1999 Annals of Botany Company Cut flowers, methyl glucoside,myo-inositol,Rosa hybrida,soluble carbohydrate.     

A Flower and Pod Staging System for Soybean

Flower and pod abscission limit soybean yield. A system forquantifying flower and pod development based on the morphologicalappearance of the flower prior to and following anthesis hasbeen developed to aid in studies of pod abscission. Changesin the appearance of the corolla, primarily the banner petal,are used to distinguish the different stages of the system.External pistil dimensions have been correlated with internalfeatures for each stage of development. From anthesis to podset, pistil length and weight increase almost two- and fivefold,respectively, and ovule development progresses from unfertilizedegg cells to embryos surrounded by cellular endosperm. Pod determinedare correlated with ovule length and width and embryo cell number.Flower and pod stages can be determined in situ, thus permittingnon-destructive observation and experimental manipulation offlowers or pods without necessarily impeding their development.Stages have been identified that indicate precisely when podset occurs and when young pods cease growing and ultimatelyabscise. This system of flower and pod staging is useful instudies designed to assess effects of abiotic or biotic stressand genetic factors on pod set and abortion. Abscission, anthesis, Glycine max (L.) Merr, embryo development, pod set     

Effects of Growth Retardants, Gibberellic Acid and Indol-3-ylacetic Acid on Stem Extension and Flower Development in the Pot Chrysanthemum (Chrysanthemum morifolium Ramat)

The growth retardants chlorphonium chloride, daminozide anda new, quaternary ammonium compound, piproctanyl bromide, allreduced shoot length and delayed the time of flowering of thepot chrysanthemum (Chrysanthemum morifolium Ramat) cv. BrightGolden Anne grown throughout in short days. The retardants delayedflowering by reducing the rate of flower bud development andnot by influencing bud initiation. In the case of chlorphoniumchloride and daminozide, a single dose of 20 or 40 µggibberellic acid (GA) completely overcame the effects on bothstem length and flowering, whereas when piproctanyl bromidehad been applied GA did not always bring about a total reversal.Responses to GA were recorded a few days after its application.Neither the retardants nor Ga altered leaf number. Only whenpiproctanyl bromide was the retardant did indol-3-ylacetic acidproduce a small but significant increase in stem length at flowering. The results are consistent with a theory of retardant actionin which gibberellins play the dominant role and strongly suggestthat these hormones are a major factor influencing both stemextension and the rate of flower-bud development in the chrysanthemum.They may promote flower development and thus hasten floweringby attracting assimilates to these organs. Chrysanthemum morifolium Ramat, stem extension, flower development, growth retardants, gibberellic acid, indol-3-ylacetic acid     

Genetic and Photoperiodic Control of the Relative Rates of Reproductive and Vegetative Development in Peas

The rates of leaf and flower production were determined in peas(Pisum sativum L.) of genotypes e sn hr (line 13), E Sn hr (line60), and E Sn Hr (line G2), to assess the role of the interactionof alleles Sn and Hr with photoperiod in development. The ratesat which flowers at successive nodes opened (AR) and leavesat successive nodes unfolded (PR) were constant. The AR wasfaster than the PR so that successive flowers opened at nodescloser to the apical bud. The rate at which this occurred wasindependent of photoperiod in line 13 but was slightly or markedlyslower in short days (SD) than long days (LD) in lines 60 andG2, respectively. The opening of flowers closer to the apicalbud of G2 peas in SD was so slow as to not be visually apparentduring the time of this study. The number of nodes between thefirst open flower and the apical bud was unaffected by photoperiodin line 13 but was greater in SD than LD in lines 60 and G2.The daylength effects are photoperiodic, since development ofG2 peas in LD with respect to the parameters measured was unaffectedby light intensity. It is concluded that photoperiod and theE Sn allele combination control the rate of reproductive developmentrelative to vegetative development in peas. The effects of ESn are magnified by the presence of the Hr allele. The constantrates of development measured are not consistent with declineof Sn allele expression with age. Delay of the rate of reproductivedevelopment relative to vegetative development correlated withdelay of apical senescence, suggesting that these processesare related. Pisum sativum, genotypes, photoperiod, flowering, reproductive development, vegetative development, senescence     

Photoperiod Sensitivity during Flower Development of Opium Poppy (Papaver somniferum L.)

Photoperiod is a major factor in flower development of the opiumpoppy (Papaver somniferum L. ‘album DC’) which isa long-day plant. Predicting time to flower in field-grown opiumpoppy requires knowledge of which stages of growth are sensitiveto photoperiod and how the rate of flower development is influencedby photoperiod. The objective of this work was to determinewhen poppy plants first become sensitive to photoperiod andhow long photoperiod continues to influence the time to firstflower under consistent temperature conditions. Plants weregrown in artificially-lit growth chambers with either a 16-hphotoperiod (highly flower inductive) or a 9-h photoperiod (non-inductive).Plants were transferred at 1 to 3-d intervals from a 16- toa 9-h photoperiod andvice versa . All chambers were maintainedat a 12-h thermoperiod of 25/20 °C. Poppy plants becamesensitive to photoperiod 4 d after emergence and required aminimum of four inductive cycles (short dark periods) beforethe plant flowered. Additional inductive cycles, up to a maximumof nine, hastened flowering. After 13 inductive cycles, floweringtime was no longer influenced by photoperiod. These resultsindicate that the interval between emergence and first flowercan be divided into four phases: (1) a photoperiod-insensitivejuvenile phase (JP); (2) a photoperiod-sensitive inductive phase(PSP); (3) a photoperiod-sensitive post-inductive phase (PSPP);and (4) a photoperiod-insensitive post-inductive phase (PIPP).The minimum durations of these phases forPapaver somniferum‘album DC’ under the conditions of our experimentwere determined as 4 d, 4 d, 9 d, and 14 d, respectively. Anthesis; days to flowering; flower bud; opium poppy; Papaver somniferum L.; photoperiod; photoperiod sensitivity; predicting time to flowering; transfer     

Venation Pattern and Fruit Development in Lomatium dasycarpum (Umbelliferae)

Venation patterns of flower and fruit, and their relationshipto fruit development, are described for Lomatium dasycarpum(T. and G.) Coult. and Rose, a member of the tribe Peucedaneae(Umbelliferae). Comparisons of these observations are made withreports of fruit anatomy for other Peucedaneae, such as Angelica,Peucedanum, and Heracleum. These comparisons indicate that thereare distinctly different patterns of development leading toa mature fruit with a similar dorsal flattening. The possiblesignificance of such observations, with regard to our understandingof generic relationships in the tribe, is discussed.     

Environmental Control of Flowering in Vicia faba L.

There is a heteroblastic change in leaflet number in many stocksof Vicia faba, the rate of change being affected by the temperatureand photoperiod under which the plants are grown. In all exceptthe earliest flowering stocks of broad beans, and particularlyat high temperatures, flower initiation shows a quantita-tivelong-day response. For full development of the initiated inflorescenceslong days are required. Flower initiation may be accelerated in all except the earliestflowering stocks of V.faba by brief exposures to low temperatures,particularly when the plants are grown in short days at hightemperatures. The response to low temperatures is more rapidat I0° C. than at 4° C. but eventually approaches saturationat both temperatures. More prolonged exposure to low temperaturesdelays flower initia-tion. The response to low temperaturesincreases with increasing plant age but can occur during embryodevelopment on the mother plant. At temperatures above 14° C, and particularly above 23°C, a reaction inhibitory to flower initiation occurs. This reactionis probably restricted to the diurnal dark periods but is operativeat all stages of the life cycle, including embryo development.Its inhibitory effects may be overcome by subsequent cold treatment,and when the low temperature processes have reached saturationsubsequent high temperatures are no longer inhibitory. Although nucleosides could accelerate flower initiation, purineand pyrimidene analogues did not, with one exception, reducethe response to low temperature treatment.     

A Quantitative Model of Reproductive Development in Cowpea [Vigna unguiculata (L) Walp.] in relation to Photoperiod and Temperature, and Implications for Screening Germplasm

Factorial combinations of four photoperiods (10 h, 11 h 40 min,13 h 20 min and 15 h) and three night temperatures (14, 19 and24 °C) combined with a single day temperature (30 °C)were imposed on nodulated plants of 11 cowpea accessions [Vignaunguiculata (L) Walp.] grown in pots in growth cabinets. Thetimes to first appearance of flower buds, open flowers and maturepods were recorded. Linear relationships were established betweenthe reciprocal of the times taken to flower and both mean diurnaltemperature and photoperiod. When the equations describing thesetwo responses are solved, the time to flower in any given photothermalregime is predicted by whichever solution calls for the greaterdelay in flowering. Thus in different circumstances floweringis controlled exclusively by either mean temperature or photoperiod.The value of the critical photoperiod is temperature-dependentand a further equation, derived from the first two, predictsthis relationship. Considered together as a quantitative modelthese relationships suggest simple field methods for screeninggenotypes to determine photo-thermal response surfaces. Vigna unguiculata (L) Walp., cowpea, reproductive development, photoperiod, temperature, germplasm     

The Role of Glucose on Flower Bud Formation in Thin-Layer Tissue 12Nicotiana tabacum L.

The effect of glucose on flower bud formation was studied inthin-layer tissue cultures of epidermal strips from flower stalksof Nicotiana tabacum L. cv. Samsun. A minimum concentration of 30 mol m^–3 glucose in the MS-mediumcontaining 1.0 mmol m^–3 of both NAA and BA was necessaryfor flower bud formation. With 150 mol m^–3 glucose a minimumstay of 10 d was required for optimal flower bud formation. Withholding glucose for a limited period at different time intervalsafter the onset of culture caused a delay in flower bud formationand did not affect previous development on glucose. The resultsindicated that competence for flower bud initiation is not restrictedto the early stage of culture. The process may start at anytime later at the appropriate glucose concentration. However,for both optimal initiation and further development of flowerbuds the presence of a metabolizable sugar is required. Incubationof the tissue on glucose is associated with higher respirationrate. Key words: Flower formation, Glucose, mannitol, Nicotiana tabacum, Respiration, tissue culture     

Development of Flat and Fan-Shaped Fruit in Actinidia chinensis var. chinensis and Actinidia deliciosa

We describe and quantify development of flat and fan-shapedfruit of Actinidia chinensis var. chinensis from inception tomaturity. Flat fruit arise from particularly large and flatfloral meristems. After bract initiation, the terminal flowerremains elliptic in cross section, produces elliptic whorlsof floral organs, and forms a flat-shaped ovary. The allometryof the ovary does not change from inception to maturity. Fan-shapedfruit develop from exceptionally flat floral meristems. Theyresult from postgenital fusion of the terminal flower with oneor two precocious lateral flowers. Timing of the fusion processvaries, resulting in a variable degree of integration of tissues.The fasciated flower has supernumerary floral organs, and isborne on a single pedicel. The histology of mature flat andfan-shaped fruit is described for commercially-grown Actinidiadeliciosa cv. Hayward. Mature flat fruit have a larger maximumdiameter, but are comparable to normal fruit in the minimumdiameter. Flat fruit have more locules and more pericarp tissuethan normal fruit, but these are not causally related to fruitshape. The flat shape can be attributed to differential planesof enlargement of cells in certain regions of the central core.Mature fan-shaped fruit are larger, and have more pericarp,core and locules than normal or flat fruit.Copyright 1994, 1999Academic Press Actinidia chinensis, Actinidia deliciosa, fruit shape, development, anatomy, fusion     

An Effect of Copper Deficiency on the Initiation and Development of Flower Buds of Chrysanthemum morifolium Grown in Solution Culture

The effects of various levels of copper on the initiation anddevelopment of flower buds in two cuhivars of Chrysanthemummorifolium grown in solution culture have been examined. Plantswere harvested at regular intervals during a short-day photoperiod,and buds scored according to an arbitrary 22-stage scale offlower development. A critical level of copper has been determinedbelow which flower bud initiation is much retarded.     

Young Reproductive Structures Promote Nitrogen Fixation in Soya Bean

In many legumes the transition from the vegetative to the reproductivephase of development is associated with a marked increase inthe rate of symbiotic nitrogen fixation. In soya bean [Glycinemax (L.) Merr.), the removal of reproductive parts at differentstages of their development showed that the increase in nitrogenfixation rate was primarily due to the presence of flower buds.The increase in the fixation rate of intact reproductive plantswas accompanied by a rapid increase in the weight of noduleson lateral roots and it is suggested that these nodules areresponsible for much of the nitrogen fixation which occurs duringreproductive growth. Maintaining plants in the vegetative stateprovided evidence which suggests that it is the flower budsand not the flowering stimulus which are responsible for theincrease in fixation rate. The marked effects on vegetativegrowth of removing reproductive parts suggests that the mechanisminvolved in the promotion of nitrogen fixation may be hormonal. Glycine max (L.) Merr., soya bean, nitrogen fixation