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1.
The main factor affecting floral initiation of Geraldton Wax-Flower (Chamelaucium uncinatum) is the photoperiod, while temperature is the major factor affecting flower development. Four weeks of short days (SD) are generally required for obtaining full flowering. The number of flowers produced per plant increases with increasing the number of SD. Under mild temperatures of 2014°C (day/night), plants initiated flowers even in long days (LD). However, fewer flowers were produced and on higher nodes as compared to SD plants. Chlormequat promoted flowering under prevailing summer conditions of high temperatures and LD. Under prevailing autumn conditions favourable for flower initiation, LD treatment or weekly sprays with gibberellic acid (GA) reduced the number of flowers per plant. Combined treatment of LD and GA reduced both the flowering percentage and the number of flowers per plant. Discontinuing the LD or the GA treatments caused a resumption of full flower initiation.  相似文献   

2.
《Scientia Horticulturae》2001,87(4):303-309
Rice flower (Ozothamnus diosmifolius, Vent.), native to east Australia, is a spring flowering perennial shrub. It is a new cut flower plant, recently introduced into cultivation in Australia and in Israel. Its response to environmental conditions, which affect growth and flowering, are not yet known. The purpose of the present study was to evaluate the effects of growth temperature, photoperiod and total solar energy on flowering. Experiments were conducted with plants of the cv. Cook’s Snow White. Plants were grown in three cycles under controlled conditions in the phytotron, at four day/night temperature regimes: 17/9, 20/12, 23/15 and 26/18°C. Two photoperiods — short day (SD) of 10 h natural day light and long day (LD) of 10 h natural light plus 10 h incandescent light — were employed. High temperatures enhanced vegetative growth but blocked flowering under both LD and SD. Under medium–moderate temperatures plants were absolute LD plants and did not flower under SD conditions. Under lower temperatures plants flowered under both LD and SD, but SD delayed flowering. High total solar radiation under LD did not affect flowering time but greatly promoted the number of flowering stems.  相似文献   

3.
Gibberellic acid (GA) promoted flowering of Gypsophila paniculata plants grown under long-day (LD) conditions at low night temperatures, which otherwise prevented the realization of the LD induction. GA did not induce flower formation of plants grown in short-days (SD), either under low winter temperatures or at the relatively high night temperatures of spring and summer, which allow flowering under LD. GA had only a marginal promotive influence under fully inductive conditions of LD and high temperatures. Thus, in gypsophila, GA substitutes for the high night temperature which is required as a background for the photoperiodic induction, but not for the long photoperiod itself.  相似文献   

4.
《Scientia Horticulturae》1986,28(3):263-270
Fourteen genotypes of Chrysanthemum morifolium were induced to flower under a gradient that ran from 3 to 35 W m−2 visible light at a daylength of 9 h. The first sign of light stress was a reduction in number of flowers, followed by delayed flowering and finally, with increasing stress, no flowering at all. The minimum irradiance required for flowering may be as low as 5 W m−2 for some cultivars, which is considerably lower than the irradiance of 16 W m−2 falling on the plants in the greenhouse in winter. Large cultivar-differences in minimum light requirement for flowering were detected.At lower temperatures, the minimum level of light required for flowering increased.  相似文献   

5.
To evaluate and describe the current status of Calibrachoa cultivars as bedding plants, the seasonal flowering of 91 commercial cultivars were compared to those of natural species using principal components analysis. The predominant flowering of the cultivars, that is, floriferous in late spring to early summer with a tendency to reduce flower production toward winter, seems to have remained unchanged from that of natural species. However, properties desired in bedding plants, such as early flowering and continuous flowering under short-day and/or low temperature conditions, appear to have been improved in a considerable number of cultivars, although there is still room for improvement. Seasonal and total floral counts were higher in many cultivars compared to natural species. Several natural species were selected for their unique flowering ability and should be evaluated as gene resources for improving the flowering of Calibrachoa cultivars.  相似文献   

6.
Night temperatures warmer than those normally used in commercial production systems promoted vegetative growth in Tagetes patula and Matthiola incana seedlings. In the short (8 h) daylength regime employed, and with a day temperature of 16°C, cool nights (8°C) had a detrimental effect, especially when imposed for 6 weeks from pricking-out rather than later. Night temperatures between 8°C and 16°C did not substitute for the long-day requirement for flowering in Matthiola after 11 weeks' growth, and there was no advantage with respect to vegetative growth in maintaining night temperatures above 12°C. Warmer nights from pricking-out promoted flowering in Tagetes but if applied later (during weeks 7–11) the positive effects were largely on vegetative growth. The implications of these findings for commercial horticulture are discussed.  相似文献   

7.
Factors influencing the number of flowers produced in Pelargonium × domesticum cultivar ‘Lavender Grand Slam’, and their rate of development after the plants had been given a period of low-temperature flower induction, were studied.Under short days progressive abortion reduced flower numbers as the temperature regime during the forcing-period was increased. Under long days this effect was less marked and the high-temperature regime advanced flowering by over a month. When long days and high temperatures were used for forcing, it was necessary to maintain a high light intensity, 335 J/cm2/day giving the best results in terms of earliness of flowering and the number of flowers produced. At lower irradiance there was some risk of flower abortion, particularly in the first inflorescence.  相似文献   

8.
Urban green areas, due to their high plant diversity, can be supportive as floral resources (nectar and/or pollen) to wild and managed pollinating insects. This research aims towards understanding the contribution of ornamental ground cover perennials as a food source for urban pollinators. We compare floral phenology and abundance, nectar and pollen production, and insect visitation to flowers of Geranium macrorrhizum, G. platypetalum and G. sanguineum, planted in the botanical garden of Lublin, SE Poland. The investigation revealed that the studied hardy geraniums exhibit many features valuable for pollinators, including large floral display (G. macrorrhizum and G. platypetalum), extended flowering period (G. sanguineum) and ample nectar and pollen reward (G. macrorrhizum). They can supply urban pollinators with a high quality food during spring and early summer time, i.e. the period of high food demand by many bee species. Moreover, hardy geraniums might be valuable plants for urban beekeeping as they are eagerly visited by honeybees. The investigated ground cover plants could therefore be considered in future city plantings.  相似文献   

9.
Dwarf geophytes have great potential for use on extensive green roofs because they often come from arid areas and can survive dry and hot summer in a dormant state. However, there has been little research regarding geophytes on green roofs. This experiment was conducted to study the performance of 26 species of geophytes on a green roof during 2005–2006 in Sheffield, UK. The geophytes were grown at two substrate depths (5 cm and 10 cm) of substrate on a green roof without irrigation. To investigate the susceptibility of geophytes to competition from a covering of permanent plants, the geophytes were grown with or without a surface vegetation layer of Sedum album. Overall, the growth, survival rate, regeneration and flowering of geophytes were more successful at a substrate depth of 10 cm than of 5 cm, probably because of improved moisture retention, fewer temperature fluctuations and the protection from digging by animals. The flowering period was limited to spring, therefore, it is recommended to combine with other plant species such as covering plants. Geophyte species did not compete much with S. album and Sedum cover had no significant effects on the growth, survival rate, regeneration and flowering of geophytes in most species. Iris bucharica, Muscari azureum, Tulipa clusiana var. chrysantha, Tulipa humilis, Tulipa tarda and Tulipa turkestanica had good performance at the substrate depth of 5 cm. In addition, Narcissus cyclamineus ‘February gold’ and Tulipa urumiensis exhibited a successful performance at the substrate depth of 10 cm.  相似文献   

10.
《Scientia Horticulturae》2003,98(4):423-431
Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.  相似文献   

11.
《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   

12.
The effect of plant age, temperature and day-length on flower initiation and development in “ K. & M. Super ” freesias has been studied.

The flowering response decreased with increasing temperature and the critical temperature for flower initiation was found to be about 21°C. An interaction of plant age, temperature, and duration of treatment was present. Short days (9 hrs.) slightly stimulated flower initiation in“ Yellow K. & M. Super” but delayed it in “ Blue K. & M. Super” freesias. Short-day treatment in the open during the summer had no significant effect, whereas shading markedly hastened flowering.

Flowering could be initiated at an early stage, but older plants were more responsive, especially those of “Blue K. & M. Super”. Optimum temperatures for flower initiation were 12-15°C., applied for 6-9 weeks after the plants had formed about seven visible leaves.

Abnormal inflorescences in freesias, recognized by enlarged bracts and irregular spacing of the florets (so-called “gladiolus-like flowers”), appeared to result from incomplete flower initiation. In extreme cases flower stalks without any flowers were formed. In order to avoid such abnormal flowering it was important that the first floret in the inflorescence should have reached a certain stage (P2) of development before low-temperature treatment was discontinued.  相似文献   

13.
Pollinator-friendly plants are often a necessary component of the management of urban ecosystem that aim to reduce the impact of the artificial urban matrix on natural pollinator populations. Nectarivorous bats are neglected components of the urban pollinator community and there is a paucity of assessments on pollinator-friendly plants that may provide urban bats with reliable, year-long resources. Crescentia cujete is a bat-pollinated Bignoniaceae with very distinctive chiropterophilous features that is often used as an ornamental species in tropical urban areas worldwide. Its flowers are large and produce copious amounts of nectar, which accumulates in the flower’s storage-shaped flowers. Thus, the species is a potential bat-friendly urban plant. We assessed the species’ year-round flower emission and nightly nectar production dynamics in a green area in northeastern Brazil, and described the behavior of its floral visitors. C. cujete showed a steady, year-round flowering pattern, with no significant seasonality. Its flowers secreted copious amounts of diluted nectar and were visited exclusively by the Pallas long-tongued bat Glossophaga soricina throughout the night at high visiting frequencies, delivering successive visits to individual flowers spaced by short intervals. Our results suggest overexploitation of floral resources from C. cujete by urban bats. Moreover, its continuous flowering and copious nectar production may become a reliable resource in an artificial environment generally lacking bat-pollinated plants, thus mitigating the effects of food shortage for urban nectar bats.  相似文献   

14.
Summary

A range of temperatures (7°C, 10°C or 13°C mean) were imposed under controlled conditions on four year old, container-grown ‘Hayward’ kiwifruit vines. The treatments were applied for periods of from one to four months during the dormant period from May to September (Southern Hemisphere). Following these treatments the vines were held at a “forcing” temperature of 16°C mean until flowering. The objective was to define the response of bud break and flowering in spring to temperatures experienced during the preceding winter. Cool winter temperatures dramatically increased flower numbers, increased the proportion of bud break, advanced the day of bud break, and increased the duration from bud break to flowering. These responses were much larger between 13°C and 10°C than they were between 10°C and 7°C. For any treatment duration, the temperature imposed during dormancy had no effect on the time of flowering. Two months at cool temperatures produced the greatest number of flowers per winter bud, with reduced numbers at three and four months. The proportion of winter buds that produced shoots showed a similar response. The Richardson chill unit is frequently used to describe the effects of winter chilling on kiwifruit. It proved unreliable as an index to integrate the effects of temperature and time on any of the developmental variables monitored in this experiment.  相似文献   

15.
A cost-efficient light control system based on weather forecasts, electricity prices and daily photosynthesis integral (DPI) was evaluated for application in the commercial production of the long-day (LD) plant Campanula portenschlagiana ‘Blue Get Mee’ and C. cochlearifolia ‘Blue Wonder’. Experiments were conducted under both autumn and spring conditions and included four treatments. Three treatments were controlled by the software system DynaLight Desktop which automatically defined the most cost-efficient use of supplemental light, -based on a predefined set point of DPI, forecasted solar irradiance and the market price on electricity. The set points of DPI in the three treatments were 300, 450 and 600 mmol CO2 m−2 leaf d−1 and the treatments were compared with a traditional LD 19-h treatment. The DPI-based light control strategy resulted in very irregular light patterns including daily periods of solar irradiance combined with supplemental light in low light periods and a night period interrupted by irregular light breaks (NB-lighting). Both campanula species flowered in the DPI-based treatments during spring, but the flowering percentage was low and non-uniform during autumn. This was caused by a combination of the irregular light, low natural light intensities and a decrease in daily light integral (DLI), and could be restored by maintaining a continuous 19 h photoperiod with incandescent lamps (<5 μmol m−2 s−1), illustrating that photoperiod was an important factor for flowering in LD species grown under low light intensities. Growth in terms of carbon gain was marginally affected by the irregular light and a 25% reduction in electricity costs was achieved without major reductions in plant quality in spring. Our results illustrate that plant production of LD species can be maintained in a cost-efficient light control system where the use of supplemental light is based on weather forecasts and electricity prices.  相似文献   

16.
Gladiolus plants were grown in winter and early spring at several densities, under natural day, or long day (LD) regimes, with low intensity light at night. LD treatment promoted flowering-percentage (by reducing “blindness”), and enhanced flower quality features, (length of stem and spike, and number of florets per spike). The effect was observed even at planting-densities of 2–3 times the normal winter density. Lighting for 1 hour at mid-night was effective, but the greatest effect was observed by lighting throughout the night. Most of the promotive effects were obtained by lighting for 4 hours as day extension or as night break, and this treatment was recommended for commercial use. Cyclic lighting of 5 minutes of light and 10 minutes of dark was as effective as continuous light for 4 hours, and light intensity of 35 lux was as effective as 130 lux.All cultivars of gladiolus grandiflorus tested responded to the LD treatment, but the miniature cultivar ‘Charm’ did not. The LD effect was especially pronounced under conditions when the normal flowering was defective, such as with high-density plantings, low temperatures and with summer cultivars.  相似文献   

17.
Summary

Floral induction in tropical trees generally follows a check in vegetative growth. However, it is not easy to identify the environmental factors involved in flowering, which normally occurs during the dry season when temperatures are also often lower. The separate and combined effects of temperature and water supply on floral induction were investigated in ‘Hass’ avocado (Persea americana), ‘Lisbon’ lemon (Citrus limon). ‘Wai Chee’ litchi (Litchi chinensis) and ‘Sensation’ mango (Mangifera indica). Low temperatures (15°/10°C or 15°/10°C and 20°/15°C compared with 30°/25°C and 25°/20°C) generally decreased vegetative growth and induced flowering in well-watered avocado, litchi and mango. A pre-dawn leaf water potential (ψL) of ?1.7 to ?3.5 MPa compared with ?0.4 to ?0.7 MPa in control avocado and litchi, and a pre-dawn relative water content (R.W.C.) of 90-93% compared with 97% or above in control mango plants also reduced or eliminated vegetative growth, but did not induce flowering. Low temperatures (15°/10°C compared with 20°/5°C, 25°/20°C or 30°/25°C) and water stress (pre-dawn ψL of ?2.0 to ?3.5 MPa compared with ?0.7 to ?0.8 MPa in controls) reduced or eliminated vegetative growth in lemon. In contrast to the response in avocado, litchi and mango, flowering in lemon was very weak in the absence of water stress at 15°/10°C or outdoors in Brisbane in subtropical Australia (Lat. 28°S), and was greatest after a period of water stress. The number of flowers increased with the severity and duration of water stress (two, four or eight weeks) and was generally greater after constant rather than with cyclic water stress. In lemon and litchi, net photosynthesis declined with increasing water stress reaching zero with a midday ψL of ?3.5 to ?4.0 MPa. This decline in carbon assimilation appeared to be almost entirely due to stomatal closure. Despite the reduction in midday CO2 assimilation, starch concentration increased during water stress, especially in the branches, trunk and roots of lemon. Leaf starch was uniformly low. The number of flowers per tree in lemon was strongly correlated with starch in the branches (r2=77%, P<0.01) and roots (r2=74%, P<0.001). In litchi, starch was lower than in lemon roots and was not related to flowering.

In separate experiments to test the interaction between temperature and water supply, low day/night temperatures (23°/18° and 18°/15°C compared with 29°/25°C) reduced vegetative growth and induced flowering in avocado, litchi and mango. None of these species flowered at 29°/25°C or as a result of water stress (ψL of ?1.5 MPa compared with ?0.3 MPa for avocado and ?2.0 MPa compared with ?0.5 MPa for litchi, and R.W.C, of 90-93% compared with 95-96% in mango). In contrast, in lemon, flowering was very weak (<10 flowers per tree) in the absence of water stress (pre-dawn ψL of ?2.0 MPa compared with ?0.5 MPa) and was only heavy (>35 flowers per tree) after stressed trees were rewatered. There were slightly more flowers at 18°/15°C than at 23°/18° and 29°/25°C in control plants, but no effect of temperature in stressed plants. Starch concentration in the roots of avocado, lemon, litchi and mango was generally higher at 18°/15°C and 23°/18°C than at 29°/25°C. Water stress increased the starch concentration in the roots of lemon and litchi and decreased it in avocado. There was no effect in mango. There was a weak relation (r2=57%, P<0.05) between the number of flowers per tree in lemon and the concentration of starch in the roots. In contrast, there was no significant relationship between flowering and starch levels under the various temperature and water regimes in the other species. In another experiment, only vegetative growth in litchi and mango occurred at 30°/25°C and only flowering at 15°/10°C. Six weeks of water stress (pre-dawn ψL of ?2.5 MPa compared with ?1.0 MPa or higher in litchi, and R.W.C, of 90-93% compared with 95% or higher in mango) in a heated glasshouse (30°C days/20°C night minimum) before these temperature treatments did not induce flowering.

Temperatures below 25°C for avocado and below 20°C for litchi and mango are essential for flowering and cannot be replaced by water stress. The control of flowering in lemon over the range of day temperatures from 18°C to 30°C differed from that of the other species in being mainly determined by water stress. Flowering was generally weak in well-watered plants even with days at 18°C. Starch did not appear to control flowering.  相似文献   

18.
The role of corm size, light and temperature in flowering of Watsonia species was evaluated to facilitate their commercial production. In addition to exhibiting desirable ornamental attributes, the species selected represented the major climatic regions in South Africa. A day/night temperature regime of 12/7 °C released vegetative dormancy in all species and thereafter elicited vernalization in Watsonia pillansii – highlighting an obligate cold requirement for this species. Flowering of Watsonia borbonica and Watsonia tabularis was not enhanced by additional chilling, but rather by long (16 h) or day-neutral (12 h) photoperiods. Microscopic examination of the shoot apical meristem revealed that extension of the 2nd leaf was a critical stage developmentally, and signified the anatomical transition to flowering. Late-development temperatures to a maximum of 25 °C ensured healthy vegetative growth and supported the maturation of the inflorescence and the opening of floret buds. Irradiance did not affect flower induction, but a minimum light intensity of 150 μmol m−2 s−1 proved essential in sustaining the energetic demands of the competitive growth and reproductive processes. Excessively high irradiance (950 μmol m−2 s−1) impacted negatively on attractiveness through increased bud blasting. Flowering success was not correlated to corm mass, but rather to the environment under which the corm was stored, or the conditions under which the plant was grown. Understanding the phenology of these species in situ and the link between flowering and season provide a useful tool for predicting the artificial requirements necessary to elicit optimal flowering under industry conditions.  相似文献   

19.
Orchids are commercially important plants with flowers that are unique and very specialized in shape and color. The flowers consist mostly of sepals, lateral petals, lip (labellum) and column, and are zygomorphic and resupinate. Whereas most orchid species have petaloid tepals in the first and second whorls, Habenaria radiata has a flower with greenish sepals and white lateral petals and lip. ‘Hishou’, one of the cultivars of H. radiata, is a floral homeotic mutant and has a petaloid median sepal and lip-like lateral sepals in the first whorl. Additionally, this cultivar often has non-resupinate flowers whereas wild-type H. radiata flowers are resupinate. In the present study, we investigated the genetic inheritance of these characters in the ‘Hishou’ cultivar by crossing it with wild-type plants. Some intraspecific hybrids, which were confirmed by PCR-RFLP analysis, had flowers with a petaloid median sepal and lip-like lateral sepals in the first whorl, indicating that these were dominant characters. Since the remainder of the intraspecific hybrids had wild-type flowers, these characters must be heterozygous in ‘Hishou’ plants. Although ‘Hishou’ plants had non-resupinate flowers, intraspecific hybrid flowers were resupinate, even though they had the petaloid median sepal and lip-like lateral sepals. This result indicates that non-resupination must be a recessive character. Since sepal-petalization and triple lip characters of ‘Hishou’ inherited dominantly, these characters can be utilized for the breeding of Habenaria species by intra- and interspecific crosses.  相似文献   

20.
The effect of mean daily air temperature (MDT) on flowering rate (the reciprocal of days to flower) was quantified for 18 species of annual bedding plants. Plants were grown in environmental growth chambers at constant air temperature set points of 5, 7.5, 10, 15, 25, or 30 °C and under an irradiance of 160–180 μmol m–2 s–1, with a 16-h photoperiod. Nonlinear mathematical equations were developed to predict the effect of MDT on flowering rate and to estimate the base, optimum, and maximum temperatures (Tmin, Topt, and Tmax), which are the temperatures at which flowering rates are zero (low temperature), maximal, and zero once again (high temperature), respectively. The estimated Tmin varied among species and ranged from 1.1 °C in French marigold (Tagetes patula L.) to 9.9 °C in angelonia (Angelonia angustifolia Benth.). Topt and Tmax were only observed for 8–10 species with the temperature range tested. Topt ranged from 19.1 °C in dahlia (Dahlia × hybrida Cav.) to 28.0 °C in blue salvia (Salvia farinacea Benth.), whereas Tmax ranged from 30.3 °C in snapdragon (Antirrhinum majus L.) to 31.7 °C in moss rose (Portulaca grandiflora Hook.). Angelonia, browallia (Browallia speciosa Hook.), cosmos (Cosmos sulphureus Cav.), dahlia, and snapdragon grown at 25 or 30 °C developed a mean of two to seven more nodes before flowering compared with plants grown at ≤15 °C. The results indicate that in many species, flowering rate in response to MDT is asymmetrical around Topt and the temperature range between Tmin and Topt is wider than that between Topt and Tmax. This information could be used to improve the predictability of flowering time of these ornamental crops and to assist growers in determining energy-efficient production temperatures.  相似文献   

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