Flower Bud Appearance Research Articles

ENVIRONMENTAL FACTORS AFFECTING FLOWERING AND FRUIT DEVELOPMENT OF OPUNTIA FICUS-INDICA CUTTINGS DURING THE THREE WEEKS BEFORE PLANTING

Opuntia ficus-indica(prickly pear) is a widespread desert perennial cactus shrub. The plants produce either lateral branches or flowers from the axillary meristems, depending on maternal and environmental influences.The flower buds develop from the axillary meristems mainly at the margin of the apical part of the terminal flat branch segments. Flower bud meristems start to be active and secrete mucus in January. The red-bracted flower buds start to appear in March/April, flowers open in May/June, and fruit matures in June/August.This study focused on the appearance of flower buds, flowers, and fruits after induction ofO. ficus-indicaone-segment branch cuttings by environmental factors during the 3-week healing period after cutting and before planting. The influence of treatments such as temperature, light intensity, and day length on flower bud appearance and fruit development is described.

Flower Morphogenesis in Rosa hybrida 'Mercedes' as Studied by Cryo-scanning Electron and Light Microscopy. Effects on Light and Shoot Position on a Branch

Flower bud development in Rosa hybrida cv. 'Mercedes' was studied in shoots grown at different irradiances and sprouting from axillary buds at different branch positions. Cryo-scanning electron microscopy and light microscopy were used to visualize, characterize and determine flower morphogenesis during early shoot development. Up to the moment of visible flower bud appearance on the plant, flower morphogenesis was divided into nine stages. This classification was based on external and internal characteristics of the primordium. All shoots of the rose 'Mercedes' whether positioned uppermost or second on a branch and whether grown at 300 or 150 μmol m-2 s-1 PAR (12 h d-1) developed equally up to flower stage 7, i.e. the stage just before visible initiation of stamen and pistils. Signs of flower bud abortion were the compactness of the flower bud at developmental stage 7 (height/width < 1·5) and the sprouting of axillary buds positioned just below the flower bud primordium. It was concluded that once a flower bud has reached a height to width ratio larger than 1·5, and once stamen and pistil developmental has started, it has passed the critical developmental stage in which abortion may occur. Flower developmental stage was closely related to shoot length. This relationship was not affected by irradiance level nor by shoot position on a branch. Therefore, cultivation treatments aimed to improve flower production by reducing flower abortion, such as supplementary lighting, will be most effective when applied during the first 2 weeks of shoot growth in which the flower develops up to stage 7.

Effect of hand pinching and plant growth regulators on seed production of field grown hybrid dahlia

Abstract The effects of hand pinching above node four on the main stem and the application of the plant growth regulators paclobutrazol and chlormequat chloride on seed production of field grown hybrid dahlia ‘Unwins Mixed’ were investigated over two seasons at the same site. Pinching reduced the spread of flowering and resulted in seed heads at approximately the same height above ground level because of the promotion of lateral branch length, but did not increase seed yield. Seed yield perplant was significantly increased following the application of chlormequat chloride at 1.5 kg a.i./ha at stem elongation in the first season, and by paclobutrazol applied at 1.0 kg a.i./ ha at the appearance of the first visible flower bud in both seasons, the former through the production of more seed heads/plant, and the latter through a significant increase in seeds/seed head in one season and seed heads/plant in the following season. Other seed yield components did not differ among treatments. Plant growth retarding effects were transitory and floral development and flower numbers were not altered by the plant growth regulators. Although results were inconsistent, chemical manipulation of this hybrid dahlia shows promise for seed production and warrants further investigation.

Modeling Inflorescence Development of the African Violet (Saintpaulia ionantha Wendl.)

The effects of temperature and daily-integrated photosynthetic photon flux (PPFDI) on African violet (Saintpaulia ionantha Wendl.) flower initiation and development were quantified to provide the basis for an inflorescence development model. The percentage of leaf axils in which an inflorescence initiated and continued development increased as the PPFDI increased from 1 to 4 mol·m-2·day-1, while the rate of inflorescence development was a function of the average daily temperature (ADT). The appearance of a visible flower bud (VB) in a leaf axil was related to the growth of the subtending leaf blade. A polynomial model based on ADT and PPFDI was used to describe leaf blade length at visible bud (LBLVB). A nonlinear model was used to describe the influence of ADT on leaf expansion rate (LER). Inflorescence appearance in the leaf axil was predicted by measuring LBL and estimating the time for the leaf blade to develop to the length required for VB. A phasic-development scale was developed to quantify inflorescence development. Days required for an inflorescence to develop from VB to first open flower was described as a function of ADT and either inflorescence height or inflorescence development stage (IDS). Days from leaf emergence to first open flower for the inflorescence initiated in that leaf axil decreased from 86 to 55 as ADT increased from 18 to 26C.

A heat‐shock promoter fusion to the Ac transposase gene drives inducible transposition of a Ds element during Arabidopsis embryo development

SummaryA heat‐shock promoter fusion to the Ac transposase gene (hs::TPase) was constructed and introduced into Arabidopsis. In five transformants containing the fusion the abundance of transposase mRNA increased approximately 120‐fold on exposure to high temperatures. Hybrid plants containing hs::TPase and a Ds element inserted in a streptomycin resistance gene (Ds::SPT) were made and these plants were self‐fertilized either after heat shocking at different stages in development or without exposure to high temperature. The progeny of these plants were sown on streptomycin‐containing medium and the frequency with which variegated or streptomycin‐resistant (strepR) seedlings occurred was used as an indication of the frequency of Ds excision. Very few of the progeny of plants not exposed to heat shock or of those heat shocked only during vegetative development were variegated or strepR. However, plants that were heat shocked after the appearance of flower buds and during seed development produced high frequencies (approaching 100%) of variegated, but very few strepR, progeny. Furthermore, when variegated seedlings were grown to maturity and self‐fertilized without further exposure to heat shock then strepR seedlings often occurred at high frequency among their progeny. Southern analysis indicated that the majority of these strepR plants contained a transposed Ds at a new location. These data indicate that in response to heat shock Ds excision frequently occurs in embryonic cells which ultimately give rise to the gametes, as well as in cells of the developing cotyledons. The importance of an inducible transposon system for transposon tagging is discussed.

Distribution and Redistribution of Molybdenum in Black Gram (Vigna mungo L. Hepper) in Relation to Molybdenum Supply

The effect of seven rates of molybdenum (Mo) supply on the distribution and redistribution of Mo in Vigna mungo (black gram) cv. Regur on a Mo-deficient sandy loam was examined from flower bud appearance to pod set in one experiment and during pod filling to maturity in another.At the three lowest Mo supply rates, N deficiency symptoms typical of Mo deficiency appeared, and shoot dry matter and shoot nitrogen content were depressed. Increasing Mo supply increased Mo concentrations in all plant parts but the response varied with Mo supply and with plant part. In leaf blades and petioles, Mo concentrations increased slightly when the Mo supply increased from severely deficient to deficient levels but further increases in Mo supply markedly increased the Mo concentrations, particularly in immature and recently matured leaves. In petioles, Mo concentrations generally exceeded those in the blades which they supported at all levels of Mo supply. At Mo rates greater than that required for maximum growth, Mo concentrations in basal stem segments exceeded those in petioles. Molybdenum concentrations in nodules exceeded those in above ground plant parts except at the highest level of Mo supply where the concentrations in basal stem segments exceeded those in nodules.In Mo-adequate plants, Mo contents in the trifoliolate leaves decreased with time suggesting that Mo was readily remobilized. By contrast, in stem segments at all levels of Mo supply, and in trifoliolate leaves in Mo-deficient plants, Mo contents remained constant or increased with time suggesting that Mo was not remobilized in all plant parts or at all levels of Mo supply. Thus, the results suggest that in black gram Mo was variably mobile, being phloem immobile at low Mo supply, but phloem-mobile in all plant parts with the possible exception of stem segments at adequate Mo supply. The relevance of these results for the development of plant tests for Mo deficiency diagnosis is discussed.

Production of choleretic substances in the capitulum, leaf and stem of Artemisia capillaris during the plant growth cycle.

Five Artemisia capillaris plants were selected at random from among a bed of twenty plants cultivated in a field for one year. Several branches were collected from each plant once a month, except in August and October, when two collections were made during budding and flowering. Each organ (leaf, stem, and capitulum) was separated from the branch and dried, and later analyzed for capillarisin and 6,7-dimethylesculetin content by high-performance liquid chromatography (HPLC). The capillarisin and 6,7-dimethylesculetin content reached maximum levels in the leaf just before the appearance of flower buds at end of July. About one month later, at the end of August during budding and flowering, capillarisin content in the capitulum reached a peak and then decreased. On the other hand, 6,7-dimethylescuretin content reached a maximum at the beginning of September, two weeks after the capillarisin maximum. The results suggest that the most appropriate time to harvest A. capillaris for use as a crude drug is between the flower bud stage and early flower stage, from late August to early September.

Effect of environment and applied chemicals on the flowering and form of Geraldton Wax ( Chamelaucium uncinatum Schauer)

Flowering in a number of cultivars of Geraldton Wax ( Chamelaucium uncinatum Schauer) is promoted by exposure to short days. For the cultivar ‘Purple Pride’ the critical photoperiod above which flowering does not occur was between 13 and 13.5 h for 3–4-month-old plants grown from cuttings. In 14 and 16 h photoperiods no flowering occurred in these young plants, although in plants older than 5 or 7 months there was often a low level of flowering. One cultivar failed to flower in any daylength and in a hybrid line there was a complex response to temperature and photoperiod. Temperatures of 20–25°C and high irradiance favoured flowering of ‘Purple Pride’. At lower temperature (below 16°C) there was poor flowering. The flowers also developed more slowly but were larger when open. Higher temperature (above 25°C) led to rapid flower bud appearance, but flower number was drastically reduced and the flowers were much smaller. Cool (12–15°C) temperatures imposed during 3–6 weeks of short days blocked the induction of flowering. By contrast, these temperatures were favourable for flowering of a hybrid between Chamelaucium floriferum and C. uncinatum, although the effect of daylength was far greater. Flower development proceeded even at these cool temperatures. Both paclobutrazol and chlormequat inhibited shoot growth and generally had little effect on flowering. Benzyladenine caused substantial branching and could either depress or promote flowering. Flower drop was triggered within 3 days with ethephon. The implications of these findings for the regulation of flowering under field and greenhouse conditions are discussed.

MODELING INFLORESCENCE DEVELOPMENT OF AFRICAN VIOLETS

The effects of temperature and irradiance on flower initiation and development were quantified to provide a basis for an inflorescence development model. The percentage of leaf axils forming an inflorescence increased as the daily integrated PPF increased from 1 to 4 mol m-2 d-1, while the rate of inflorescence development was a linear function of temperature from 18 to 26C. The appearance of a visible flower bud in the leaf axil was correlated with leaf blade length of the subtending leaf. Mathematical functions were used to describe leaf blade length at the time of visible flower bud as a function of temperature and irradiance, and also to describe the influence of temperature on the rate of leaf extension. The time of visible flower bud in the leaf axil was then predicted by measuring the current length of the subtending leaf blade and estimating the time required for the leaf blade to extend to the length required for visible flower bud appearance. A phasic development scale was used to describe the developmental status of an inflorescence from visible flower bud to anthesis. A model was then created which predicted time to anthesis based upon temperature and the current stage of inflorescence development.

Effect of paclobutrazol on inflorescence production and seed yield in four white clover (Trifolium repensL.) cultivars

Abstract Abstract Growth retardants may increase seed yield in herbage legumes. The growth retardant paclobutrazol was applied at a rate of 1.0 kg a.i./ha at either inflorescence initiation (9 October) or first flower bud appearance (2 November) to four white clover cultivars (‘Grasslands Kopu’, ‘Grasslands Pilau’, ‘Grasslands Huia’, ‘Grasslands Tahora’) which differed in leaf size from large to small, and the effects were observed. Paclobutrazol application in October significantly increased inflorescence numbers in all four cultivars, and advanced their appearance in all but Kopu. November application initially delayed inflorescence appearance, but then increased the rate of inflorescence appearance and significantly increased inflorescence number. Leaf size was reduced in all cultivars, and inflorescences were elevated above the canopy because petiole length was reduced. The November application significantly increased seed yield in all four cultivars, whereas the October application increased seed yie...

Prediction of nitrogen fertilizer requirement in cotton using petiole and sap nitrate

Abstract With the aim of refining methods of determining plant N status of cotton, we measured nitrate concentrations in petioles and xylem sap in field experiments over three seasons. Main plots were rotation/tillage treatments which were split for fertilizer N. Petiole nitrate concentration was about 30 g N/kg at appearance of flower buds (squares). Rotation and N rate had highly significant effects on petiole nitrate concentration in every season. There was a linear decline in petiole nitrate with stage of development (measured in day degrees, base 12°C), particularly between 600 and 900 day degrees from sowing. The relationship between fertilizer N requirement and petiole nitrate concentration was exponential, with greatest precision when high fertilizer rates were required. The relationship between fertilizer N requirement and the rate of decline in petiole nitrate was linear, giving equal precision over the N fertilizer range. Optimum plant N status was represented by a petiole nitrate concentration...

The Effect of Temperature on the Production and Abscission of Flowers and Pods in Snap Bean (Phaseolus vulgaris L.)

The effect of temperature on production and abscission of flower buds, flowers and pods was studied in a determinate snap-bean cultivar (cv. Tenderette). Under moderate temperature (e.g. 27/17 °C) the onset of pod development was associated with cessation of flower bud production and with enhanced abscission of flower buds. Raising night temperature from 17 °C to 27 °C strongly reduced pod production, mature pod size and seeds per pod, while an increase in day temperature from 22 °C to 32 °C had smaller and less consistent effects. Pod production under high night temperature was not constrained by flower production since 27 °C at night promoted branching and flower bud appearance. Under 32/27 °C day/night temperature the large reduction in pod set was due to enhanced abscission of flower buds, flowers and young pods (< 3 cm). Flowers had the highest relative abscission followed by young pods and flower buds. Therefore, the onset of anthesis and of pod development were the plant stages most sensitive to night temperature. Pods larger than 3 cm did not abscise but usually aborted and shrivelled under high night temperature. The effects of 32/27 °C were not due to transient water stresses and were observed even under continuous irrigation and mist-spraying.

Temperature driven leaf unfolding rate in Hibiscus rosa-sinensis

Leaf unfolding rate of Hibiscus rosa-sinensis cultivars ‘Brilliant Red’ and ‘Pink Versicolor’ was determined in the 5–35°C temperature range at intervals of 6°C. Plants of neither cultivar survived at 5°C, and growth was very slow at 11°C. The rate of leaf unfolding was similar for the two cultivars in the studied temperature range. Daily leaf unfolding rate for hibiscus was described by a cubic polynomial function of temperature ( T) where leaves day −1 = 0.06289 − 0.02026 · T + 0.001750 · T 2 − 0.00002983 · T 3. Based on this function, predicted leaf unfolding varied from 0.012 leaves day −1 at 11°C to a maximum of 0.229 leaves day −1 at 32°C. A linear function (leaves day −1 = − 0.1130 + 0.01148· T) approximated the curvilinear relationship in the range from 10–30°C. A degree-day relationship was calculated to 0.0115 leaves per degree day using the linear function with a base temperature of 9.8°C. To unfold one leaf, 87 degree-days were required as determined by the developed linear model. A linear model was developed from the linear function where leaf unfolding was 0 at temperatures < 10°C and leaf unfolding was calculated at 30°C at temperatures ≥ 30°C. The cubic function and the linear model predicted a similar leaf unfolding rate based on hourly average temperatures recorded in a Florida commercial greenhouse during two times of the year. During a 78-day period from 25 February to 14 May, 9.95 and 9.98 leaves were predicted to unfold by the linear and cubic models respectively. During a 65-day period from 21 July to 24 September, 12.28 and 12.04 leaves were predicted to unfold by the linear and cubic models respectively. The predicted leaf unfolding rate was compared with actual leaf unfolding for the nine cultivars ‘Aloha Pink’, ‘Brilliant Red’, ‘Euterpe’, ‘Florida Sunset’, ‘Painted Lady’, ‘Pink Versicolor’, ‘Sundance’, ‘Tawny’, and ‘Vista’. Predicted leaf unfolding was within 0.9 leaves of observed leaf unfolding for all cultivars over a 7-week period after pinching. After about 7 weeks, the models progressively overpredicted leaf unfolding. Over-prediction was correlated with the appearance of flower buds.

主要畑夏雑草の生育特性，特に出穂・着らいに及ぼす日長および温度条件の影響

主要畑夏雑草の生育特性，特に出穂・着らいに及ぼす日長および温度条件の影響

Flowering and bolting in carrot. II. Prediction in growth room, glasshouse and field environments

Rates of bolting and flowering in carrots cv. Chantenay Red Cored, measured as the reciprocals of days to first internode visibility and flower bud appearance respectively, were shown to relate linearly to a thermal time of vernalization derived from data obtained in controlled environments. Days elapsed from the end of vernalization to the start of visible bolting and flowering bore a curved relationship to thermal time of vernalization. The model curves also predicted closely the bolting and flowering responses of carrots to vernalization at different temperatures in controlled environments and under markedly different conditions in the field. Time taken from the end of vernalization to flowering and bolting decreased with increasing thermal time of vernalization, particularly between ca. 110 and 400°Cd. Vernalization beyond 400°Cd had less effect on the timing of these processes. The percentage of plants flowering increased asymptotically with increasing thermal time of vernalization up to ca. 400°Cd w...

Temperature and Photosynthetic Photon Flux Influence Chrysanthemum Shoot Development and Flower Initiation under Short-day Conditions

Abstract The effects of photosynthetic photon flux (PPF), day temperature (DT) and night temperature (NT) on leaf number, leaf unfolding rate and shoot length were determined for chrysanthemum (Dendranthema grandiflora Tzvelev. ‘Bright Golden Anne’) grown under short day (SD) conditions. A functional relationship was first developed to predict if flower bud appearance would occur within 100 SD under a given set of environmental conditions. All combinations of DT and NT in the range from 10° to 30°C were predicted to result in flower bud appearance at higher PPF than 10.8 mol·day−1·m−2. The number of leaves formed below the flower increased quadratically as DT and/or NT increased from 10° to 30°. As PPF increased from 1.8 to 21.6 mol·day−1·m−2, one to two fewer leaves were formed per shoot. Rate of leaf unfolding increased linearly with increasing average daily temperature from 0.2 leaves/day at 10° to 0.5 leaves/day at 30°. Internode length was highly correlated with the difference between DT and NT (DIF = DT – NT) such that increasing DIF from –12° to 12° resulted in progressively longer internodes.

Binding of spermidine to a unique protein in thin-layer tobacco tissue culture.

The mechanism by which spermidine induces the appearances of floral buds in thin-layer tobacco (Nicotiana tabacum) tissue culture was studied by following the fate of the radioactive compound. [3H]Spermidine was taken up rapidly by the tissue, and after a brief lag, a portion was bound to trichloroacetic acid precipitable macromolecules. Such binding increased to a maximum on day 4 of culture, coinciding with the onset of bud differentiation, and declined thereafter until shortly before flowering. About 82% of the label in the trichloroacetic acid precipitate remained as spermidine, 14% was metabolized to putrescine, 3% to spermine, and 1% to gamma-aminobutyric acid. Spermidine was covalently bound to a protein with a molecular size of about 18 kilodaltons. Hydrolysis of this protein and analysis of the labeled entities revealed 81% spermidine, 16% putrescine, and 3% spermine. This post-translational modification of a unique protein by attachment of spermidine may be causally connected to the appearance of flower buds in thin-layer tobacco cultures.

Relations between photoperiod, temperature, abscisic acid, and fall dormancy in alfalfa (Medicago sativa)

Three alfalfa (Medicago sativa L.) cultivars differing in fall dormancy were examined for endogenous abscisic acid content in relation to fall dormancy. The alfalfa cultivars studied were 'Beaver' (dormant type), 'Lahonton' (semidormant type), and 'Moapa 69' (nondormant type). Alfalfa seedlings were grown in controlled-environment chambers set at a 16-h photoperiod (16 h light: 8 h dark) and 20:15 °C (light:dark) for 55 days. They were cut and then regrown under environmental conditions simulating summer and fall in western Canada. In leaf samples, the ABA level increased from about 200 in 3-week-old plants to more than 1200 ng/g fresh weight in 8-week-old plants. After cutting, abscisic acid levels dropped abruptly and then increased gradually, reaching a peak level at the stage of the appearance of flower buds. The peak of abscisic acid content was highest in 'Beaver', next highest in 'Lahontan', and lowest in the nondormant type, 'Moapa 69'. At the 6th week of regrowth, abscisic acid content in 'Beaver' was found to be 2200 ng/g fresh weight, which is the highest reported level in nonstressed plants of any species. The analysis of variance suggests photoperiod, temperature, and photoperiod × temperature interaction all have a significant effect on alfalfa regrowth and on abscisic acid content. Under long days and cool temperatures, the amount of foliage regrowth and the characteristic of fall dormancy are manifestly correlated. There is no apparent link between endogenous abscisic acid content and fall dormancy.

Day-neutral flowering in some Desert Blepharis spp.

In the desert areas of Israel, Sinai and the neighbouring countries, there are three species of Blepharis. In addition at least six different populations of types not yet classified were also found in various locations and habitats. Differences such as rates of root elongation in response to temperature, structure of inflorescences and spiny bracts, and mechanisms of seed dispersal were found in these species and types. In all of them, irrespective of the growing conditions, three pairs of leaves and one terminal inflorescence develop above the cotyledons. A lateral branch from the axil of each of the pairs of upper leaves bears two pairs of leaves and a terminal inflorescence. From these branches, additional lateral branches sometimes appear in the axil of two upper leaves, again bearing two pairs of leaves, and a terminal inflorescence, and so on. Flowering in these plants was found to be day-neutral. The quantity and distribution of rain, soil humidity and temperature seem to regulate the age of the plant at flower-bud appearance and flowering. The ecological importance of this behaviour is discussed.

INFLUENCE D’UN PRE-TRAITEMENT AU FROID ET DE LA TEMPERATURE NOCTURNE SUR LA CROISSANCE, LE DEVELOPPEMENT ET LE CONTENU EN ELEMENTS MINERAUX DE PLANTS DE POINSETTIA

To achieve more rapid adaptation of plants grown under a constant or split night temperature regime, two poinsettia cultivars (Euphorbia pulcherrima Willd ex. Klotzsch), Annette Hegg Dark Red (AHDR) and Annette Hegg Top White (AHTW), were given a cold pretreatment (PF). The PF was a 13 °C air temperature regime provided for 15 h a night during a 10-day period. The number of days to the first visible flower buds and to anthesis was longer for both cultivars having received a PF than the control plants (no pre-treatment). For AHDR only, plant height, top dry weight, the number and bract area were significantly lower after the PF when considering the average of the night temperature treatments. Regardless of the cultivar tested, no significant differences in bract diameter and root dry weight were observed between the control plants and those given a PF treatment. Whether the two cultivars were given a PF treatment or not, the split night temperature (TNP) of 16.3/14.2 °C caused a nonsignificant delay, from the appearance of first visible flower buds to anthesis, compared to those held at 16.7 °C. The most important delay of these parameters as well as the greatest reduction of bract area was obtained under a 10.8 °C night temperature. The TNP of 16.6/10.8 °C produced plants (PF or control), of both cultivars with a greater bract number and top dry weight. For the two cultivars given a PF treatment, the levels of nitrogen, phosphorus, calcium, and magnesium were greater when considering the means of the night temperature treatments.Key words: Euphorbia pulcherrima, cold pretreatment, night temperature, split night temperature