The effect of quantum flux density and net photosynthetic rate on morphology and time to flower of hybrid geraniums

Three cultivars of 63-day-old hybrid geraniums (Pelargonium × hortorum Bailey) were grown under high (800–1200 mE m^?2 s^?1), medium (300–600 mE m^?2 s^?1) or low (100–160 mE m^?2 s^?1) quantum flux densities. Plants grown under low light and 25% greater total leaf area but 25% lower dry weight than plants grown under medium or high levels, regardless of cultivar. Time to flower in all cultivars was negatively correlated with quantum flux density, and specific leaf weight and leaf thickness were positively correlated to net photosynthetic rate. ‘Sprinter Scarlet’ and ‘Sooner Red’ had similar correlation coefficients (r) for most relationships, but r values for ‘Ringo’ were generally not as strong. Quantum flux density appears to affect both organogenesis and maturation of the flower.     

Influence of almond × peach hybrids rootstocks on flower and leaf mineral concentration,yield and vigour of two peach cultivars

Flower and foliar nutrient content of ‘Queen Giant’ and ‘Tebana’ peach [Prunus persica (L.) Batsch] on six almond × peach hybrids rootstocks (‘Adafuel’, ‘Adarcias’, ‘GF 677’, ‘Cadaman’, ‘Garnem’ and ‘Felinem’) were determined during one season. The mineral elements analysed were: N, P, K, Ca, Mg, Fe, Mn, Zn, Na and Cu. Leaf N concentration in ‘Queen Giant’ was the highest on ‘Cadaman’ and ‘GF 677’ and the lowest on ‘Adarcias’. The P, Fe and Zn concentrations in flowers and leaves were significantly correlated. The leaf chlorophyll concentration at 120 DAFB was positively correlated with Fe floral concentration and with K, Zn and Na leaf concentration, in ‘Queen Giant’, and with K and Mn leaf concentration, in ‘Tebana’. In ‘Queen Giant’, the greatest trunk cross-sectional area was exhibited with ‘Felinem’ and ‘Garnem’ and the lowest with ‘Adarcias’. In contrast, the greater yield efficiency was found on ‘Adarcias’. In ‘Queen Giant’, a negative correlation was found between yield efficiency and Ca in leaves and in flowers. A positive correlation was observed between tree vigour and flower Fe, flower Ca and leaf Ca concentration. Correlation was also found between yield efficiency and Mg in ‘Tebana’ flowers. In ‘Queen Giant’, ‘Felinem’ rootstock showed the weakest balanced nutritional values (ΣDOP index) compared with other rootstocks.     

Effects of shading on growth rate,flower initiation and flower development of Begonia x semperflorens-cultorum

Seedlings of Begonia x semperflorens-cultorum Hort. ‘Scarletta’ were grown under 0,45, or 57% of ambient light in a glass greenhouse. Shoot dry weight, lateral shoot leaf area, total leaf area, and node number decreased under increasing shade over time. Histological examination of shoot apices indicated that floral initiation occurred two to three weeks later in plants under 57% shade than those under ambient light or 45% shade. Plants under ambient light reached visible bud about five weeks before those under 57% shade and the time of floral development from visible bud to anthesis was also shorter for plants in ambient light compared with those grown under 45 and 57% shade. Staminate flower numbers on the first inflorescence increased under 45% shade compared with ambient light and 57% shade while pistillate flower numbers were unchanged.     

The response of rose plants to evaporative cooling: Plant water status and CO2 fixation

Evaporative cooling of rose plants ‘Baccara’ and ‘Marimba’ by “fan and pad” resulted in a substantial increase in shoot water potential, a decrease in leaf diffusive resistance, and an increase in CO₂ fixation. The mid-day increase in the leaf diffusive resistance was not accompanied by a decrease in the CO₂ uptake. This phenomenon is attributed to the existence of continuous air flow through the plant canopy. Evaporative cooling also increased leaf area and the fresh weight and dry matter content of flower buds and stems.     

Anatomy of flower differentiation and abortion,in relation to the growth and development of hybrid tea-rose seedlings

From germination until anthesis or flower bud abortion, seedlings from ‘Sonia’ × ‘Hadley’ were grown in both a greenhouse (full daylight, 20° C) and a growth room (8 Wm^?2, 8 h, 20°C) of the IVT-phytotron. Plastochron was an external indication of the stage of flower differentiation. Flower differentiation in flowering and aborting seedlings ran parallel up to petal-segregation. Flower differentiation in aborting seedlings did not proceed beyond stamen formation. Early abortion, which also caused absence of the upper leaf, occurred without, later abortion with, an abscission zone in the flowerstalk.     

Controlling the growth and development of rose plants after planting

The effects of pinching and lateral bud removal (deshooting) on the development of structural shoots, the number of flowers, and the average flower stem length in young rose plants were examined, using the cultivars ‘Baccara’, ‘Sonia’ and ‘Belinda’. The effect of deshooting on flower yield varied with each cultivar. It did not affect the number of ‘Baccara’ flowers, but increased ‘Sonia’ and ‘Belinda’ flower production by 50% and 75%, respectively. Leaving flowers to bloom out on plants before the start of commercial harvest resulted in a decrease in the length of the flower stems and also reduced the beneficial effect of deshooting on flower yield. Deshooting enhanced structural shoot formation (“bottom breaks”). Pinching flower buds of structural shoots increased the number of ‘Baccara’ flowers in comparison with pruning these shoots to 40–60 cm, as in common practice. Deshooting of the structural shoots of ‘Sonia’ and ‘Belinda’ increased the number of flowers in both cultivars.     

Competition for water between inflorescences and leaves in cut flowering stems of Grevillea ‘Crimson Yul-lo’

Summary

Grevillea cv. ‘Crimson Yul-lo’ has large bright red terminal inflorescences on leafy stems and has recognised commercial potential as a cut flower crop. A major limitation is its relatively short vase-life, often terminated by early wilting of the inflorescence despite apparently turgid leaves. An investigation of the water relations of cut Grevillea ‘Crimson Yul-lo’ stems revealed that the water potential of inflorescences on intact stems in vases was significantly higher (i.e., less negative) than that of leaves from day-0 to day-3 of vase-life. Thereafter, the water potential of inflorescences declined more rapidly than that of leaves, accompanied by visible wilting of the tepals and styles of individual florets. Removal of leaves from the stems reduced both water uptake and water loss, and delayed the onset of a negative water balance in the inflorescence. Bagging of entire stems, leaves only, or inflorescences only, with micro-perforated plastic film to reduce transpiration, reducing leaf number to reduce leaf area, or supplying abscisic acid to reduce leaf stomatal aperture, all aided relative fresh weight retention by stems and extended vase-life. Four or six leaves on a stem caused greater loss in inflorescence water content than zero or two leaves. Considered collectively, these findings show that competition for water between the inflorescence and the leaves in cut Grevillea ‘Crimson Yul-lo’ stems contributes to the onset of inflorescence wilting and their short vase-life.     

Partitioning of 14C-assimilate in Easter Lily as affected by growth stage and flower removal

Three weeks before anthesis, flower buds of Easter Lily plants received 47 and 12% of ¹⁴C translocated from Leaf 5 (upper) and 25 (middle), respectively, whereas the bulb received 5 and 52%, respectively. Flower bud removal increased the fraction in the bulb to 52% (Leaf 5) and 63% (Leaf 25). At anthesis, the flowers received 78% (Leaf 5) and 65% (Leaf 25) of translocated ¹⁴C-assimilate, nearly all of which was in the second flower which was still expanding. Less than 5% of the ¹⁴C from either leaf moved to the bulb in intact flowering plants, but upon flower removal, the bulb received 26 and 59% of the labelled assimilate from Leaf 5 and 25, respectively. Five weeks after anthesis, nearly 85% of the ¹⁴C-assimilate from either leaf was in the bulb. The fraction of ¹⁴C moving into the daughter bulb increased from less than 10%, 3 weeks before, to over 50%, 5 weeks after anthesis. Regardless of treatment, sink activity of the daughter scales was 2- to 12-fold higher than that of the mother scales. Although much of the current assimilate from the upper half of the intact lily shoot moves to flowers before anthesis, flower-bud removal is an effective way to increase carbon supply to the bulb.     

Chlormequat (CCC) induced enhancement of flowering in carnation in relation to changes in carbohydrate metabolism

CCC was sprayed 3 times on carnation cultivar ‘Hanacy’ grown in pots, in concentrations ranging from 10 to 100 p.p.m. CCC treatments generally enhanced floral initiation. This effect was reflected by earlier flower production and considerable increase in flower yield. Enhancement of floral initiation by CCC was coincident with increased amylase and invertase activities as well as with higher content of reducing sugars.     

Effects of sink removal on leaf photosynthetic attributes of rose flower shoots (Rosa hybrida L., cv. Dallas)

Two experiments were conducted under greenhouse conditions to evaluate the effects of sink removal (flower shoot harvest and debudding) on the gas-exchange capacity (i) of leaves left on the parent shoot after flower shoot harvest and (ii) of flower shoot leaves after flower-bud removal. In the first experiment, gas-exchange measurements were performed on three 5-foliate leaves (leaf 1: uppermost parent shoot leaf, and two leaves inserted just below: leaves 2–3). It was found that, after bud sprouting, the leaf nearest to the young growing shoot (leaf 1) experienced a significant reduction in leaf maximum net CO₂ assimilation rate, A_lm, stomatal conductance, g_s, and transpiration rate, E_l, over time in comparison to the corresponding values observed for leaves 2–3. Leaf water use efficiency, WUE, significantly changed over time, while the ratio of leaf internal to ambient CO₂ concentration, C_i/C_a, was rather conservative throughout the entire shoot growing period. In the second experiment, leaf gas-exchange measurements were performed for adult flower shoots that were either debudded or left intact. Both types of shoots exhibited a similar along-shoot distribution pattern of physiological fluxes, g_s, and WUE. Bud removal did not significantly affect the magnitude of gas-exchange, with the exception of E_l. One week after bud removal, only slight differences were observed for A_lm, g_s and E_l between the two types of shoots. These results suggest (i) that the contribution of the uppermost parent shoot leaf to the assimilates demand of newly growing shoot significantly affects its photosynthetic capacity; and (ii) that flower-bud removal does not change the overall photosynthetic capacity of the flower shoot leaves, which divert the surplus of produced assimilates towards alternative sink organs and plant reserve pools.     

Influence of ethanol on ethylene biosynthesis and flower senescence of cut carnation

Ethanol in the holding-solution inhibited climacteric ethylene (C₂H₄) biosynthesis and decreased the respiration rate 60% during a 7-day period in cut carnation flowers. Conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to C₂H₄ was inhibited by adding ethanol to the holding-solution. Simultaneously, ACC-induced senescence in carnation flowers was inhibited by ethanol. Ethanol was the most effective alcohol in delaying carnation flower senescence of the tested series methanol, ethanol, propanol, tert-butanol and n-butanol. Ovary development was also inhibited in carnation flowers by ethanol. The senescence of Easter lily flowers (Lilium longiflorum) and tulip flowers (Tulipa gesneriana) was not delayed by ethanol.     

反义ACO 基因导入获得瓶插寿命长的香石竹植株

 通过农杆菌( Agrobacterium tumefaciens) 介导法, 利用香石竹叶片作外植体, 将反义香石竹ACC 氧化酶基因导入香石竹‘黄星’品种, 通过PCR 扩增、Southern blot 检测, 证明反义ACC 氧化酶基因已整合到香石竹基因组。研究发现, 叶龄、乙酰丁香酮等对转化率有着较大影响。通过叶片的两度选择分化, 大大减少了转化嵌合体比例。转基因植株在隔离条件下栽培, 开花正常, 切花在25 ℃条件下瓶插寿命较对照延长了4 d。     

Effect of photoperiods before,during and after vernalization on flower initiation and development and its varietal difference in Japanese bunching onion (Allium fistulosum L.)

Summary

To control the bolting of Japanese bunching onion (Allium fistulosum L.) photoperiodically, the effect of photoperiods before, during and after vernalization on flower initiation and development and the varietal differences were investigated using the two mid-season flowering cvs Kincho and Asagi-kujo, and a late-season flowering cv. Cho-etsu. A long-day photoperiod (LD, 16 h) given before vernalization inhibited flower initiation. Especially, the bolting rate of ‘Asagi-kujo’ decreased by about a half, compared with the short-day photoperiod (SD, 8 h). The interaction between the effect of night temperature (3°C, 7°C, 11°C or 15°C) and the effect of the photoperiod (SD and LD) during vernalization was also investigated. In ‘Kincho’, LD did not affect flower initiation at 3°C, but inhibited flower initiation at 7°C, 11°C and 15°C. In ‘Asagi-kujo’, flower initiation was significantly inhibited by LD under all temperature conditions. This inhibitory effect was stronger at 11°C and 15°C than at 3°C and 7°C. In ‘Cho- etsu’, LD significantly inhibited flower initiation at 3°C and 7°C, and flower initiation rarely occurred at 11°C and 15°C. In this study, generally, LD during vernalization inhibited flower initiation in all cultivars. Thus Japanese bunching onion required a short-day photoperiod in flower initiation, which was stronger in ‘Asagi-kujo’ and ‘Cho-etsu’ than in ‘Kincho’. From these results, we conclude that low temperature and a short-day photoperiod complementarily induce flower initiation in Japanese bunching onion. Varietal differences exist in the requirement of low temperature and a short-day photoperiod: the primary requirement in ‘Kincho’ is low temperature and that in ‘Asagi-kujo’ is a short-day. After flower initiation, the early stage of flower development is day-neutral, and after the floret formation stage, a long-day photoperiod promotes flower development and elongation of the seedstalk.     

Effects of high temperature on flower colour and anthocyanin content in pink flower genotypes of greenhouse chrysanthemum (Chrysanthemum morifolium Ramat.)

Summary

The relationship between the intensity of flower colour and changes in the content of the main anthocyanins under various controlled temperatures was examined in order to clarify the effects of high temperature on flower colouration in six pink flower genotypes of greenhouse chrysanthemum (Chrysanthemum morifolium Ramat.). Poor colouration of flowers was observed at 30°C in all genotypes except ‘Chatoo’. This genotype showed little difference in flower colour between different temperature treatments. The degree of change in flower colour differed depending on the genotype, whereas no clear differences in flower colouring were observed between Summer – Autumn flowering and Autumn-flowering genotypes. All genotypes showed lower contents of the two anthocyanins tested [cyanidin 3-O-(6’’-O-monomalonyl- -glucopyranoside) and cyanidin 3-O-(3’’,6’’-O-dimalonyl- -glucopyranoside)] at higher temperatures. Therefore, flower colour changes were attributable to changes in these two main anthocyanins. Differences in colouration between genotypes and temperature conditions were also detectable in values that were measured using a colorimeter. Changed parameters that were visually verifiable were the a* value, representing the degree of red colour, and the C* value, representing chroma. For ‘Sei-Monako’, which showed visually greater differences between temperature treatments, the a* and C* values were low under high temperature conditions. On the other hand, in ‘Chatoo’, the differences detected by eye and those in a* and C* values between temperature treatments were small. In addition, the present results indicate that mean temperature is more important than either day or night temperature in determining the degree of flower colouration.     

The interaction of a dormancy-breaking cold treatment,ancymidol, and ethephon in relation to stem elongation and flower production of Lilium cultivars

Stem elongation of Lilium cultivars ‘Black Beauty’, ‘Jamboree’ and ‘Nutmegger’ was lessened by treating the bulbs with ancymidol (10 p.p.m.) or ethephon (500 p.p.m.). Ancymidol was the more effective inhibitor of stem elongation, although applied at a much lower concentration. Application of the growth regulators prior to a dormancy-breaking cold treatment provided more effective control of stem elongation than post cold-treatment application. The total number of flowers and the number of secondary flowers per stem of ‘Black Beauty’ and ‘Nutmegger’ were increased by treating the bulbs with ancymidol. However, unlike the optimal time for lessening stem elongation, enhancement of flower production was greatest when ancymidol was applied after completion of the cold treatment. Ethephon was unsatisfactory, since it inhibited flower production by ‘Black Beauty’ and ‘Nutmegger’, while ‘Jamboree’ was relatively insensitive to it, as indicated by a lack of inhibition of flower production and a small degree of inhibition of stem elongation.     

观赏荷花新品种‘石城锦绣’

观赏荷花'石城锦绣'是从'锦霞'自然杂交后代中选育出的复色、重瓣型新品种.植株大型,立叶高57～82 cm,叶长径33～43 cm,短径27～39 cm,花高75～96 cm,花径15～21 cm,花瓣数91～110枚.花复色,瓣尖紫红色,中部粉色,基部黄色.花初开盘状,后期碟状.     

Anatomical and growth effects of ethephon on hyacinths and Narcissus during greenhouse forcing

‘Blue Blazer’ hyacinths and ‘Jack Snipe’ Narcissus were sprayed to run-off with 2000 mg l⁻¹ ethephon when average leaf length was 10 cm. Ethephon reduced the length of the flower scape of ‘Blue Blazer’ by 20% at “bud” stage of development, and by 28% at full flower. No effect on date of flowering was observed. The floral scape length reduction of ‘Jack Snipe’ was 27% at the “goose-neck” stage and 25% at full flower. Anatomical and stereological examinations revealed significant cellular and structural differences between treated and untreated plants of both species. The cell sizes of the treated plants were smaller and the intercellular space sizes were decreased. Endodermal cell separation was reduced and pith deterioration was delayed. There was a 20–30% increase in the number of cells in the treated plants; a phenomenon not usually associated with ethephon. Thus, while ethephon normally promotes senescence, in these studies, it enhanced cell division.     

Guide for Authors

Bromeliad growers report severe leaf quality problems for Aechmea cultivars grown under commercial greenhouse conditions. In this research, a leaf damage ‘sensitive’ and ‘insensitive’ A. cultivar were compared for their C-metabolism and hydrophysiology under these greenhouse conditions. Stomata opening index indicated CAM (Crassulacean acid metabolism) for both cultivars, with 45–50% open stomata around 4:00 a.m. and 5–10% in the afternoon. Malic and citric acid were the major organic acids present in the leaves, with diurnal malic acid accumulation during the night. The leaf damage ‘sensitive’ cultivar showed higher malic acid accumulation than the ‘insensitive’ cultivar (200 μmol/gfw versus 170 μmol/gfw). Leaf osmotic potential and turgor pressure were linked with diurnal malic acid fluctuations: organic acid accumulation during the night generated high leaf turgor pressures (up to +0.86 MPa).A leaf damage sensitivity test was designed and confirmed previous experiences of several bromeliad growers. Both cultivars showed higher leaf damage percentages (98 and 78%) when leaf malic acid accumulation was high. We attribute this elevated sensitivity to lethal turgor pressures and consider them to be caused by the water capturing mechanism generated by high organic acid accumulation. Under current greenhouse conditions, this water capturing mechanism can be disastrous for plant leaf quality. Especially, under high relative humidity, hindering plant transpiration and stimulating water uptake by dew formation, leaf quality could be endangered.     

A role for carbohydrate levels in the control of flowering in citrus

Girdling in October of small or large fruitless branches increased 2–3-fold both starch content of leaves and flower numbers as compared with ungirdled ‘Murcott’ mandarin trees. Autumn girdling and GA₃ treatments were both effective and additive in increasing starch contents of leaves and twigs of ‘Shamouti’ orange trees. GA₃, however, had the expected effect of depressing the reproductive inflorescences in both girdled and ungirdled branches, while girdling had the opposite effect. Girdling and fruit removal in October also additively and dramatically increased flower production in ‘Murcott’. Lowtemperature regimes in a phytotron caused young ‘Minneola’ budlings to flower earlier in the season and more profusely, while having no effect on starch content of leaves and twigs. The interactions of increased carbohydrate content and gibberellin in the control of flower formation in citrus are discussed.     

The changes in the growth pattern of peas caused by flower formation

Weekly growth analyses were made of a very late flowering pea line (‘L’) and its medium flowering (‘M’) and early flowering (‘E’) mutants, grown at three photoperiods.The number of stem nodes of young vegetative plants is not affected by the genotype (L, M, E) nor by the day length. In older plants node numbers tend to increase with the day length, but the rate of node formation decreases with flower formation.Internode length is also independent of genotype, but it increases with day length, even in very young plants, and shows a further considerable increase when flower formation starts.Hence, flower formation clearly marks changes in the growth pattern, consisting of a decrease in node formation and an increase in internode length. These effects are primarily brought about by the genes which determine the rate of flower formation.