Production protocol development for greenhouse cut Linaria, Lupinus, and Papaver flowers

Linaria maroccana Hook. f. Ann., ‘Lace Violet’, Lupinus hartwegii ssp. cruikshankii Lindl. ‘Sunrise’ and Papaver nudicaule L. ‘Meadow Pastels’ seeds were directly sown into 105 cell plug trays and received either ambient light or supplemental high intensity discharge (HID) lighting. For each species, a 2 × 3 × 3 factorial was used with two light intensities during propagation, three transplant stages, and three night temperatures. Seedlings were transplanted at the appearance of 2–3, 5–6, or 8–9 true leaves. Transplanted Linaria and Papaver seedlings were placed at 5/11, 10/16, or 15/21 ± 1 °C night/day temperatures and Lupinus seedlings were placed at 15/24, 18/25, or 20/26 ± 2 °C night/day temperatures. For this study, the optimum production temperature for Linaria was 10/16 °C as the cut stems produced at 15/21 °C were unmarketable and production time was excessively long at 5/11 °C. At 10/16 °C, Linaria seedlings should be transplanted at the 2–3 leaf stage to maximize stem number, stem length and profitability. For Lupinus the optimum temperature was 15/24 °C due to long stems and high profitability per plant. Lupinus seedlings should be transplanted at the 2–3 leaf stage when grown at 15/24 °C to obtain the longest and thickest stems; however, $/m² week was higher for plants transplanted at the 8–9 leaf stage due to less time in finishing production space. For Papaver, the 15/21 °C temperature was optimal as that temperature produced the longest stems in the shortest duration, resulting in the highest $/m² week. At 15/21 °C Papaver plants should be transplanted at the 2–3 leaf stage. Supplemental HID lighting had no effect on any of the species.     

Effect of light conditions on the development of the inflorescence in tomato

By growing tomato plants (Lycopersicon esculentum Mill.) in 4 different light regimes (2 photoperiods — 8 and 16 h — combined with 2 light intensities — 9,000 and 18,000 ergs cm^?2 s^?1, it was shown that increasing light integrals hastened flower initiation, greatly promoted the development of the inflorescence and increased the rates of leaf production and the growth of the stem. In similar light integrals, flower initiation was earlier and inflorescence development far better in short photoperiods than in long ones; the rates of leaf production were almost the same and stem growth was greater in long days.Transfer experiments from favourable to insufficient light conditions and inverse transfers at different times during the life of the plant indicated that light conditions were critical at the time of, and after, the macroscopic appearance of the inflorescence. At that stage, a transfer to low light conditions for 10 days induced complete abortion of the truss in our growth conditions. The effect of a transfer from insufficient to favourable light conditions was slower since at least 15 days in these latter conditions were required in order to achieve the development of the inflorescence.     

Interacting effects of temperature integration and light intensity on growth and development of single-stemmed cut rose plants

Energy conservation in horticulture can be achieved by allowing temperatures to fluctuate within predefined bandwidths instead of using rigid set points for heating and ventilation. In temperature integration, plants are supposed to compensate effects of temporarily deviations of the average temperature some time later by deviations in the opposite direction. However, little is still known on the effects of integration periods exceeding 1 day. In this study, effects of temperature integration on growth and development of single-stemmed cut rose plants were determined. Pruned rose shoots were placed in climate chambers in which light levels switched daily (2 days integration period) or weekly (14 days integration period) from high light intensity (300 μmol m⁻² s⁻¹) to low light (150 μmol m⁻² s⁻¹). Temperatures were kept continuously at 20 °C (control) or changed with the light intensity (phase, high temperature at high light intensity, low temperature at low light intensity) or changed opposite to the light intensity (counter phase). Bandwidths of temperature integration were 0, 6 or 10 °C. Under these conditions, buds grew out to harvestable shoots in approximately 45 days. At both integration periods, shoot length was significantly reduced with increasing bandwidths of temperature integration. Shoot dry weights were reduced when a bandwidth of 10 °C was applied. At both integration periods, rates of photosynthesis were primarily determined by light intensity. However, in the counter phase treatments, photosynthesis rate at high light and low temperature was reduced compared to the high light condition of the control. Under these conditions, starch content increased to approximately 10%, suggesting a feedback inhibition of the rate of photosynthesis. However, this did not (yet) affect plant growth or development.     

Effect of temperature and daylength on flower initiation and runner formation in two everbearing strawberry cultivars

Plants of the everbearing cultivars ‘Revada’ and ‘Rabunda’ were placed at constant temperatures of 14, 20 and 26°C and daylengths of 8, 16 and 24 hours, consisting of 8 hours daylight prolonged with 0, 8 or 16 hours in can descent light, light intensity 0.8 W/m² visible radiation.Flower initiation and runner formation occurred irrespective of temperature and daylength. The duration of runner formation depended on temperature and daylength and was longer at 20 and 26°C than at 14°C and longer at 16 and 24 hours than at 8 hours.The results are discussed.     

Effect of the light intensity on forcing of the strawberry cultivar ‘Glasa’

Plants of ‘Glasa’ were forced early in growth rooms at 14°C under a 16-hour day consisting of 8 hours of mercury light, light intensities 12, 24 or 36 W m^?2, supplemented by 8 hours of incandescent light, intensity 0.8 W m^?2. Light intensity affected the flowering-date, the number of inflorescences, the number of flowers per inflorescence, stamen development and fruit set. For successful forcing, a light intensity of at least 24 W m^?2 is necessary.     

Effect of temperature,daylength and light intensity on growth and development of Dipladenia sanderi Hemsl. ‘Rosea’

Dipladenia sanderi Hemsl. ‘Rosea’ (syn.: Mandevilla sanderi (Hemsl.) Woodson ‘Rosea’) was grown in a glasshouse at 12, 15, 18 and 21°C, daylengths of 8 or 20 h, natural daylight, and natural daylight supplemented with cool-white fluorescent lamps (10 W m^?2).Time from propagation to unfolded flower decreased with increasing temperature, and at 12°C there were relatively few flowers in the inflorescences. The time to flower opening was not influenced by daylength, but with 20 h there were more buds in the first developed inflorescence and the petals were larger than with 8 h. In addition, the vegetative growth was favoured by 20 h. Supplementary lighting shortened the developmental time to unfolded flower, but the flowers were smaller than in natural light only.The growth and development varied according to the time of year. Dipladenia was able to bloom all year round, except in January and February. The low light intensity in November and December probably made it impossible for the buds to develop into flowers in January and February.     

Environmental and cultural effects on vegetative growth and flowering of selected “bedding” ornamentals. I. Night temperature

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.     

Effects of low temperature storage on growth and transplant quality of non-grafted and grafted cantaloupe-type muskmelon seedlings

Grafting is a unique horticultural technology that allows the grower to select an alternate, compatible root system with natural disease resistance for their desired crop. Short-term storage of grafted seedlings under low temperature may extend the production window of grafted seedlings, reduce the labor input and increase production of grafted seedlings with a small propagation capacity. To evaluate the low temperature storage conditions, Cucumis melo ‘Olympic Gold’ seedlings were grafted onto Cucurbita maxima x Cucurbita moschata ‘Tetsukabuto’ rootstock and stored for a period of 2 or 4 weeks at 9, 12, or 15 °C under 12 μmol m⁻² s⁻¹ photosynthetic photon flux (PPF). The study demonstrated that grafted seedlings could be stored at 12 °C for 4 weeks without significant dry mass accumulation or effects on post-storage growth and development. Grafted seedlings stored at 15 °C for 4 weeks had a significant increase in dry mass and stem elongation; this was not observed for the non-grafted seedlings stored under the same conditions, suggesting that the rootstock enhanced the scion growth at lower temperatures than optimal for muskmelon. Storing muskmelon seedlings at 9 °C caused chilling damage but the damage was pronounced for non-grafted seedlings than grafted seedlings. ‘Tetsukabuto’ rootstock, an interspecific squash, presumably has a chilling tolerance and increased the storability of muskmelon seedlings. Further optimization is needed but there is potential for using this technique as a tool for mass production of grafted muskmelon seedlings.     

Red:far-red light ratio and far-red light integral promote or retard growth and flowering in Eustoma grandiflorum (Raf.) Shinn

Night break treatment was applied to Eustoma grandiflorum ‘Nail Peach Neo’ using light sources with different red (R: 660 ± 30 nm): far-red (FR: 730 ± 30 nm) ratios or FR light intensities in order to investigate growth and flowering responses. Flower initiation and induction were promoted by night break treatment with a low R:FR light source, but was delayed by a high R:FR ratio. The promotion or delay of flower bud formation was accompanied by a decrease or an increase, respectively, in the number of nodes on the main stem at anthesis to the first floret. The difference between date of visible bud with plants under night break treatment and that of the control was approximated with high accuracy by a sigmoid function of the logarithms of R:FR ratio. The threshold R:FR ratio demarcating the promotion and delay of date of visible bud was about 5.3 under the experimental conditions used. The critical R:FR ratios for promotion or delay of visible bud would be about 0.5 and 50.0, respectively. In addition, the time from planting to visible bud was approximated with an exponential function of FR light intensity. The maximum acceleration of date of visible bud by long-day treatment would be 20 days, and the critical FR light intensity would be 2.0 μmol m⁻² s⁻¹. It is concluded that growth and flowering of E. grandiflorum can be regulated by long-day treatment using light sources with different R:FR ratios or FR light intensities.     

The role of calcium in regulating photosynthesis and related physiological indexes of cucumber seedlings under low light intensity and suboptimal temperature stress

The response of photosynthesis, antioxidant enzyme activity, and proline content to low light intensity and suboptimal temperature in Cucumis sativa L. seedlings pretreated with either distilled water, 10 mM CaCl₂, 1 mM LaCl₃, 3 mM ethyleneglycol-bis-(2-aminoethyl) tetraacetic acid (EGTA) or 0.05 mM chlorpromazine (CPZ) were investigated. The results showed that 10 mM CaCl₂ led to an increase in photosynthetic rate (Pn), carboxylation efficiency (CE), ribulose 1,5-biphosphate carboxylase (RuBPCase) activity, chlorophyll content, peroxidase (POD) and catalase (CAT) activity, and proline content of cucumber seedlings under low light intensity and suboptimal temperature, in comparison with the distilled water-pretreated seedlings. However, LaCl₃, EGTA and CPZ were in contrast to CaCl₂. These results suggest that CaCl₂ has beneficial effect on photosynthetic adaptation to low light and suboptimal temperature stress in cucumber seedlings. This might be related to the observed increase in RuBPCase activity, alleviation of lipid peroxidation and enhancement of osmoregulation, with these effects being inhibited by LaCl₃, EGTA and CPZ.     

Analysis of light and sucrose potencies on petal coloration and pigmentation of lisianthus cultivars (in vitro)

To understand how the synthesis of petal pigments is influenced by light and sucrose, a cut flower culture was carried out with and without sucrose in the medium using different cultivars of lisianthus (Eustoma grandiflorum Grise.). At low light intensity, lightness (L¹) increased and chroma (C¹) decreased. In the presence of sucrose, lightness (L¹) decreased and chroma (C¹) increased. Light intensity and sucrose exerted significant influences on the percentage distribution of different anthocyanidins and total anthocyanin in lisianthus flower petals. Flowers from detached buds cultured in sucrose containing media showed a significant increase in anthocyanin concentration in all the cultivars; ‘Asuka no Asa’, ‘Mickey Rose’ and ‘Asuka no Kurenai’ at a light intensity of 1400 to 2100 lx. Furthermore, more anthocyanin was produced in the sucrose media. The amount of anthocyanin in the petals increased gradually with the lengthening of the photoperiod, whereas flavonol content showed no significant variation in response to light intensity or photoperiod. We found that the lightness, chroma and petal color of the flowers were influenced by sucrose and light intensity through a change in total anthocyanin concentration in petals. The variation in flower color caused by light and sucrose, determined on the basis of CIELAB color diagram, provides for a more accurate color notation in lisianthus.     

LED光照条件下低温弱光贮藏对辣椒种苗质量的影响

随着我国设施蔬菜种植面积和蔬菜育苗产业的不断扩大,蔬菜商品苗的贮藏和运输成为育苗产业的重要环节。以辣椒品种农大24为试材,研究穴盘成苗在不同低温弱光环境下的形态指标与生理指标变化,旨在明确适合辣椒种苗长期贮藏或长途运输的适宜环境条件。结果表明:温度为11℃,R∶B为1.9的荧光灯且光照强度为30μmol·m~(-2)·s~(-1)、光照周期为12h·d~(-1)的贮藏环境和R∶B为1.3的LED且光照强度为15μmol·m~(-2)·s~(-1)、光照周期为24h·d~(-1)的贮藏环境均能满足14d辣椒种苗贮藏和运输,有效地维持了种苗质量。相比于荧光灯,高光效和低能耗的LED光源更适用于辣椒种苗的低温弱光贮藏和长途运输。     

Interaction of photoperiod and temperature in the control of growth and dormancy of Prunus species

Growth and dormancy induction of seedlings or micropropagated plants of three Prunus species were studied under controlled environment conditions. All the species tested, P. cerasus L. and P. insititia L. (two cultivars each), and P. avium L. were insensitive to photoperiod at high temperature and maintained continuous growth in both 10 and 24-h photoperiods at 21 °C. At lower temperatures, however, growth was controlled by the interaction of photoperiod and temperature, the species and cultivars varying somewhat in their responses. At 9 °C growth cessation was induced regardless of day-length conditions in the plum rootstocks ‘St. Julien A’ and ‘Weito’ as well as in the sour cherry rootstock ‘Weiroot’, whereas in the sour cherry rootstock ‘Gisela 5’ growth cessation took place in short day (SD) only. At intermediate temperatures (12 and 15 °C) growth cessation occurred in SD only in both sour cherry cultivars. In P. avium seedlings on the other hand, growth cessation in SD was only induced at 9 °C, continuous but reduced growth taking place also in SD at all higher temperatures. Growth rates increased progressively with increasing temperature under long day (LD) conditions in all species, and this was associated with increased internode length in LD compared with SD conditions. Production of new leaves was unaffected by photoperiod at high temperature, but was higher in LD than in SD at lower temperatures. After growth cessation at low temperature the plants developed winter buds and became dormant also in LD conditions. These results demonstrate that, like several species of the Pomoidae subfamily of the Rosaceae, these Prunus species are insensitive to short photoperiods at relatively high temperatures. However, the photoperiodic response of the Prunus species is highly temperature dependent, and the transition temperatures for shifts in the photoperiodic response mode vary among the species.     

低温弱光对不同黄瓜品种幼苗光合作用的影响

 在低温(15 ℃) 弱光(100μE·m^-2·s^-1) 的胁迫下, 供试黄瓜品种幼苗的光补偿点开始升高, 叶绿素a 荧光动力学的有关参数Fv/ Fm、qp 、ΦPS Ⅱ ( Y) 值和参与光合作用碳同化的关键酶RuBP 羧化酶活性明显下降。这一结果表明PS Ⅱ的原初光能转换效率和电子传递以及碳同化均受到抑制, 从而使幼苗对弱光的利用能力下降。然而在逆境的诱导下, 黄瓜幼苗的适应性逐渐增强, 上述各项指标恢复到处理前的水平。试验结果还表明, 保护地品种对低温弱光逆境的调节适应能力高于露地品种。     

The effect of light,darkness and temperature on micropropagation of the pear rootstock BP10030

There was no effect of irradiance level on surviving percentages of shoot tip explants of the pear rootstock BP10030, but low irradiance stimulated the initial growth of the explant. Irradiance had a strong effect on shoot multiplication. With an increase in photosynthetic photon flux (PPF) from 10 to 80 μmol m^?2s^?1, shoot number and length and shoot fresh and dry weights increased. The greatest number of shoots and the longest ones were obtained with a 16 h photoperiod, while the highest fresh and dry weight of shoots were produced with a 24 h photoperiod. Rooting percentage and the number of roots were markedly promoted under 80 μmolm^?2s^?1 PPF. Photoperiods of 8, 16 and 24 h produced similar effects on rooting percentages and the numbers of roots. Four to seven days of darkness were the optimum for rooting. Rooting percentage and the number of roots increased with increased temperature during darkness between 5 and 25°C. A further increase in dark temperature up to 30°C reduced rooting percentage and root number.     

Temperature and photoperiod control of morphology and flowering time in two greenhouse grown Hydrangea macrophylla cultivars

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

Flowering control in Watsonia: Effects of corm size,temperature, photoperiod and irradiance

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.     

不同昼温和光照强度对西瓜断根嫁接苗生长和生理特性的影响

为确定西瓜断根嫁接苗成活后的最佳昼温和光照强度,研究了不同昼温和光照条件下,西瓜断根嫁接苗生长和生理特性的变化。试验结果表明,180μmol·m-2·s-1光照强度处理下的西瓜断根嫁接苗质量显著优于100μmol·m-2·s-1光照强度处理,说明在一定的范围内,增加光照强度能显著提高西瓜断根嫁接苗的质量。24℃昼温处理下的西瓜断根嫁接苗的生长速率略低于28℃和32℃昼温处理,但是该处理下的嫁接苗较为健壮,积累了较多的干物质,具有较高的根冠比和壮苗指数,受到的伤害较小,更符合西瓜嫁接壮苗的标准。     

内源水杨酸参与黄瓜叶片光合系统对低温胁迫的响应

 为了探讨内源水杨酸（salicylic acid,SA）在黄瓜幼苗光合系统响应低温胁迫中的作用机制, 采用高效液相色谱法测定低温下黄瓜叶片中内源SA 含量的变化;通过SA 合成抑制剂Paclobutrazol（Pac, 100 μmol · L^-1）喷施和外源SA（50 μmol · L^-1）饲喂的方法调节内源SA 含量,并测定不同处理幼苗的叶 绿素荧光参数和光合碳同化关键酶基因的转录水平。结果显示：低温引起黄瓜幼苗内源SA 含量升高,Pac 预处理抑制SA 的积累。低温导致PSⅡ的最大光化学效率（F v/F m）、实际光化学效率（Φ PSII）、潜在光化 学活性（F v/F o）和光合电子传递效率（ETR）等降低,叶片光化学猝灭参数[（Y（NO）]升高;内源SA 含量降低使PSⅡ活性下降幅度增大,加重了叶片的光损伤程度。低温下PSⅡ吸收的光能分配于光反应的 部分减少,而以非光化学反应的过剩能量耗散Ex 为主要的光能分配途径,内源SA 含量降低会加剧光能 向Ex 的分配。低温时喷施Pac 的幼苗中Rubisco 小亚基基因（RbcS）和碳酸酐酶基因（CA）的表达水平 显著低于对照植株。对喷施Pac 的幼苗外源饲喂SA 后,内源SA 含量升高,低温下叶片光合活性得到有 效恢复,光损伤降低,光能分配趋于合理,RbcS 和CA 的表达水平升高。上述结果表明,低温下内源SA 的积累有助于维持黄瓜叶片中较高的光系统活性和碳同化能力,从而保护光合系统,降低低温胁迫对植 物的损伤。