Quality Of Cut Flowers Research Articles

COBALTO COMO RETARDANTE DE LA SENESCENCIA DE Lilium HÍBRIDO ORIENTAL EN POSTCOSECHA

The quality of cut flowers is affected due to long periods of exposure to warm temperatures, water stress and mechanical damages. Several studies have identified technical issues to prolong the life of cut flowers, standing out the use of preservative solutions which may also inhibit ethylene biosynthesis. Cobalt chloride (Co) effects on weight, consumption of solution, SPAD units in leaves, content of nitrogen, cobalt, potassium, calcium, magnesium and iron, and postharvest life in stems of ‘Star Gazer’ and ‘Star Fighter’ Oriental Hybrid Lilium were evaluated. Floral stems were obtained from Villa Guerrero, Estado de México, and transported in dry conditions to the laboratory, where a 2 x 5 factorial experiment in a completely randomized design was conducted. Solutions containing sucrose as a carbon source at 4 % and the following Co concentrations: 0.0, 0.1, 0.2, 0.4 and 0.8 mM were used. This establishes that 0.1 and 0.2 mM Co delayed the symptoms of senescence in Lilium stems.

Hormonal regulation of leaf senescence in Lilium

In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA4) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA4 and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers.

EFFECT OF GA3 AND BA ON POSTHARVEST QUALITY AND VASE LIFE OF GERBERA CUT FLOWERS

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Postharvest Technology in the Global Market EFFECT OF GA3 AND BA ON POSTHARVEST QUALITY AND VASE LIFE OF GERBERA CUT FLOWERS

Effects of time and duration of short-day treatments under long-day conditions on flowering of a quantitative short-day sunflower (Helianthus annuus L.) ‘Sunrich Orange’

The effects of short-day (SD) treatment on differentiation, development and anthesis of flower buds, and on cut flower quality were investigated in a leading cut sunflower (Helianthus annuus L.) cultivar, Sunrich Orange, a quantitative SD plant. Plants were cultivated under long-day (LD) conditions with night interruption lighting from 2200 to 200h. SD treatment (11.5h photoperiod) for 1, 2, or 3 weeks was commenced at the cotyledon, two true leaves, or four true leaves stage. The control plants were grown under LD conditions throughout the experimental period. SD treatment for 1 or 2 weeks promoted flower bud initiation even when delivered at the cotyledon stage (9 days after sowing), indicating that the juvenile phase is very short in this cultivar. Flower differentiation and development were also accelerated by the SD treatment, and resulted in 19–39 days earlier anthesis. The quality of cut flowers was improved by SD treatment to desirable characteristics such as decreased weight, shortened stem and reduced stem diameter. The present study suggests that under LD conditions such as found in summer, SD treatment for 2 weeks from the cotyledon or two true leaves stage can promote LD-delayed flowering of quantitative SD sunflower plants without reducing cut flower quality.

Effects of Nitrogen Concentration on Growth and Nutrient Uptake of Anthurium andraeanum Lind. Cultivated in Coir under Different Seasonal Conditions

Coir is used around the world as a cultivation medium for plants; its commercial popularity is the result of its availability, low cost, and environmentally friendly characteristics. It is used as a medium in the hydroponic cultivation of Anthurium (Anthurium andraeanum Lind.) in Taiwan and is a new source for cut flower production around the world. Little is known about the nutrient requirements of Anthurium cultivated in coir under fluctuating climatic conditions. The objective of this study was to evaluate the influences of various nitrogen (N) concentrations on the growth and nutrient uptake of Anthurium cultivated in coir under different seasonal conditions. Four levels of N concentration in nutrient solution were used: 79 mg·L−1 (NS79 treatment), 105 mg·L−1 (NS105 treatment), 158 mg·L−1 (NS158 treatment), and 210 mg·L−1 (NS210 treatment) with NS105 serving as the control. The effects of N concentration and seasonal fluctuations on Anthurium were measured in dry weight, leaf growth, flower growth, and nutrient uptake at different growth stages during the 2-year study period. The results show that the dry weight, leaf area, and flower number were higher in plants receiving NS105 and NS158 treatments than those receiving NS79 and NS210 treatments. However, the NS158-treated plants produced better quality cut flowers than the NS105-treated plants in the first year of cultivation as indicated by their wider, circular spathe. Retarded growth of NS79-treated Anthurium was the product of insufficient N supply and reduced carbon (C) assimilation. The excess supply of N in the NS210 treatment resulted in small potassium (K) and magnesium (Mg) uptakes, which in turn resulted in poor growth in the second year of cultivation. However, the nutrient supplies in the NS158 and NS210 treatments yielded better Anthurium growth during the initial stage than the NS79- or NS105-treated groups. Regardless of plant growth, flower yield, and nutrient uptake, there were significant interactions between N treatments and seasonal fluctuations in subtropical conditions during year-round cultivation. We concluded that the limiting factor in Anthurium growth and yield during the spring and summer is the N supply, whereas climate conditions are the limiting factor during the fall and winter.

Hydrogen peroxide in the vase solution increases vase life and keeping quality of cut Oriental × Trumpet hybrid lily ‘Manissa’

Hydrogen peroxide (H2O2) is an important signal molecule involved in diverse plant developmental processes. Oriental×Trumpet hybrid lily, lilium ‘Manissa’ was used to investigate the effects of H2O2 in the vase solution on the vase life and keeping quality of cut flowers. The results show that the optimum concentration (600μM) caused an increase in vase life, from 9.8 days in control to about 12.8 days. Concentrations of 800 and 1200μM resulted in negative effects. Concurrently, 600μM H2O2 resulted in the maximum flower diameter and the maximum number of days for full flower opening. Moreover, the H2O2 scavenger ascorbic acid (ASA) or the H2O2 inhibitor diphenylene iodonium (DPI) reversed the positive effects of 600μM H2O2 on vase life and flower diameter. Treatments with 600μM H2O2 delayed leaf and petal senescence and flower opening for some days. Additionally, 600μM H2O2 treatments significantly reduced the relative degree of decline of leaf relative water content (RWC), leaf chlorophyll, petal water-soluble carbohydrate and cut flowers fresh weight. However, petal electrolyte leakage in 600μM H2O2 treatments showed the minimum variations. Together, these results indicated that H2O2 treatments at the proper dosage prolonged the vase life of cut lily and enhanced postharvest quality by retarding the degradation of RWC, chlorophyll, carbohydrate as well as cut flowers fresh weight and simultaneously keeping membrane integrity.

IMPROVING PRODUCTION QUALITY OF LILY FLOWERS BY USING ARBUSCULAR MYCORRHIZAL FUNGI AND YEAST AS A VIABLE ALTERNATIVE TO ETHYLENE INHIBITORS

The experimental trial was consummated throughout two successive seasons (2010 and 2011) at Ornamental Plants Research and Landscape Dep., Hort. Res. Inst, Giza. It intended to find out the individual effect of mycorrhizal colonization and yeast or the combination between both as a biofertilizer. Besides the combined effect with half dose of NPK as preharvest treatments on ethylene production by flowers and keeping quality of cut flowers of Lilium asiaticum cv. Nello. The obtained results showed that all treatments significantly stimulated most of the studied characters compared with that gained from control plants. The inoculation of Lilium with either AM fungi and /or yeast supported the highest values of flower vase life and longevity of flowers and leaves. The addition of AM fungi solely or combined with yeast and/ or ½ NPK gave the maximum flower opening percentage, increased flower diameter, water uptake as well as the percentage of increase in fresh weight. The same combination revealed that leaves had higher total chlorophylls content and the flowers had higher total sugars%. In respect to ethylene production, it was noticed that Mycorrhizal colonization either solely or in combination with yeast and/or ½ NPK decreased flower ethylene production. Thus, mycorrhizal colonization may be a viable alternative to toxic ethylene inhibitors such as silver thiosulfate, since STS has proven to be environmental pollutant.

국화 수확 후 관리기술의 최근 연구 동향

Chrysanthemum is a cut flower species that normally lasts for 1 to 2 weeks, in some cases 3-4 weeks. This has been attributed to low ethylene production during senescence. Reduction in cut flower quality has been attributed to the formation of air embolisms that partially or completely blocks the water transport from the vase solution to the rest of the cut flower stem, increasing hydraulic resistance which may cause severe water stress, yellowing, wilting of leaf, and chlorophyll degradation. Standard type chrysanthemum can be harvested when buds were still tightly closed and then fully opened with the simple bud-opening solution. Standard type chrysanthemum can also be harvested when the minimum size of the inflorescence is about 5-6 cm bud which opened into the first flower full-sized flower. While spray varieties can be harvested when 2-4 most mature flowers have opened (40% opening). Cut flowers are sorted by stem length, weight, condition, and so on. Standard chrysanthemum is 80 cm length for standard type and 70cm for spray type. Pre-treatment with a STS, plant regulator such as GA, BA, 1-MCP, chrysal, germicide, and sucrose, significantly improved the vase life and quality of cut flowers. It is well established that vase solutions containing sugar can improve the vase life of cut chrysanthemum. Chrysanthemum is normally packed in standard horizontal fiberboard boxes. Chrysanthemum should normally be stored at . Precooling resulted in reduction in respiration, decomposition, and transpiration activities as well as decoloration retardation. There was significant difference between wet storage in 3 weeks and dry storage in 2 weeks. In separate pulsing solution trials, various germicides were tested, as well as PGRs to maintain the green color of leaves and turgidity. Prolonging vase life was attained with the application of optimal solution such as HQS, , GA, BA and sucrose. This also retarded senescence in leaves of cut flower stems. Fresh cut chrysanthemum can be transported using a refrigerated van with . Increasing consumption and usage of cut chrysanthemum of various cultivars would require efficient transport system, and effective information exchange among producer, wholesaler, and consumer.

Far-red Light Supplemented with Weak Red Light Promotes Flowering of Gypsophila paniculata

A low red (R): far-red (FR) ratio is known to promote flowering of Arabidopsis and several long-day cut flowers, whereas not much information is available on the effects of single light qualities and their combinations on flowering. Therefore, the effects of light quality on the flowering of Gypsophila paniculata were investigated using light-emitting diodes (LEDs) emitting the following lights: FR, R, and blue (B). Flowering and flower budding were observed under long-day conditions with FR, while no flowering was observed under short-day conditions. Promotion of flowering and flower budding was increased under FR supplemented with R compared to FR alone. Although generally R inhibits flowering in long-day plants, a certain intensity of R, for example, the R:FR ratio between 0.23 and 0.71, may be necessary for effective promotion of flowering. In contrast, B supplementation of FR was not effective at the ratio in this study in inducing flowering and flower budding. The quality of cut flowers produced under long-day conditions with LEDs that promoted flowering was not lower than that under incandescent lamps. These results will provide basic knowledge for the development of LED bulbs as a replacement for incandescent bulbs.

日没の時間帯からの短時間の昇温処理がスプレーギクの生育，開花および切り花品質に及ぼす影響

スプレーギクにおいて，冬季の加温コスト低減を目的として，日没の時間帯からの短時間の昇温処理（以下，EOD-heating）の適切な処理法とその効果について検討した．‘セイプリンス’および‘レミダス’を用いて，栄養成長期，花芽分化期および花芽発達期の各生育ステージにおけるEOD-heatingの処理法を検討した結果，栄養成長期では，日没の時間帯～3時間17°Cとし，その後朝まで9°Cとすることで，処理期間中の生育はやや劣るものの，夜間15°C一定管理と同等品質の切り花が得られた．同様に，花芽分化期では，日没の時間帯～7時間20°C，その後13°C，花芽発達期では，日没の時間帯～3時間17°C，その後11°Cとすることで，それぞれ18および15°一定管理と同等品質の切り花が得られた．また，これら各生育ステージの処理を組み合わせ，21品種でEOD-heatingの適応性を検証した．その結果，到花日数は，EOD-heating区では慣行区と比べて8品種で同等となり，13品種で有意に増加したが，そのうち11品種の増加日数は3日以内であった．また，品種によって切り花長，切り花重および花序数の減少や花首長の増加が認められたものの，19品種において秀品の規格を満たすものとなった．これらのことから，夜間の温度管理技術として，燃料消費量の削減が見込めるEOD-heatingを利用できることが示された．

Evaluation of several holding solutions for prolonging vase-life and keeping quality of cut sweet pea flowers (Lathyrus odoratus L.)

Cut spikes of sweet pea (Lathyrus odoratus L.) were kept in 2% sucrose, 200ppm 8-hydroxyquinoline sulfate (8-HQS), pulsing treatment with 200ppm 8-HQS in combination with 2% sucrose for 12h, pulsing the spikes with 0.2mM silver thiosulfate (STS) for 1h and pulsing with 0.2mM STS for 1h followed by 2% sucrose solution. Therefore, this study aimed to see their effects on keeping quality and vase-life of the cut flowers. A control (deionized water) and a standard preservative were also included in the experiment. The results showed that all treatments had improved the keeping quality and vase-life of the cut flowers comparing to control ones. Among all these treatments, the 8-HQS combined with 2% sucrose showed the best water uptake, water balance, percentage of maximum increase in fresh weight of the cut flower stems and vase-life which was extended up to 17days. Moreover, this keeping solution retarded the chlorophyll as well as carbohydrate degradation. However, anthocyanin concentrations were increased by treatments with sucrose alone or STS followed by sucrose during the postharvest life. It has been concluded that 200ppm 8-HQS combined with 2% sucrose solution has the potential to be used as a commercial cut flower preservative solution to delay flower senescence, enhance post harvest quality and prolong the vase-life of sweet pea cut flowers.

Effect of Potassium Fertility Levels on Gladiolus Yield Quality of Cut Flowers and Corm production

Eight cultivars of Gladiolus “Deciso, Hong Kong, Jessica, Jester Ruffled, Madonna, Peters Pears, Rose Supreme and White Friendship” were evaluated for relative productivity in Peshawar, Pakistan over two years and at three levels of potassium (0, 100 and 200 kg K ha -1 ). There was a considerable variability in yield and quality of cut flowers as well as corm and cormels numbers in the cultivar and year with limited influence of potassium levels. Cultivars irrespective of years and potassium showed significant differences in all vegetative and floral characteristics studied during the experiment. Similarly years affected significantly all the growth parameters except first and last florets persistency and diameter of daughter corms. Potassium levels significantly affected only floret’s size at full open stage, last florets persistency and number of cormels per mother corm. There was a significant interaction between years and cultivars against all growth characteristics except size of first florets at color showing as well as first and last florets persistency. A variation in the effect of potassium levels regarding number of daughter corms and cormels per mother corm of gladiolus cultivars was observed. Last florets persistency was significantly affected by an interaction among years, potassium levels and cultivars. Rose Supreme and Jessica proved superior and were recommended for commercial cultivation in Peshawar, Pakistan.

Effects of different nutrient solution formulations on yield and cut flower quality of gerbera (Gerbera jamesonii) grown in soilless culture system

This research was conducted to determine the effects of different nutrient solution formulations on the yield and quality of cut flowers and growth of gerbera plants in substrate culture system. Five different nutrient solution formulations were used. The gerbera plantlets were planted into pots filled with perlite and peat mixture, and values of flower yield and cut flower quality criteria, and several parameters related to growth performance such as number of daughter plants, root growth criteria, plant fresh weight were obtained. The best results of cut flower yield, flower quality and plant growth were obtained from gerberas nourished by the “ColakoAŸlu-2” nutrient solution formulation which consists of 150 ppm N, 31 ppm P, 234 ppm K, 30 ppm Mg, 100 ppm Ca, 15 ppm S, 8 ppm Fe, 5 ppm Mn, 1.5 ppm B, 2 ppm Cu, 3 ppm Zn and 0.2 ppm Mo. The highest flower yield was 38.67 flowers per plant in this solution. The highest value of the number of daughter plants (3.53/plant) in gerbera was determined in the “ColakoAŸlu-2” nutrient solution formulation. Key words: Gerbera jamesonii, nutrient solution formulation, quality, yield, cut flower, substrate culture.

UV-C irradiation induces defence responses and improves vase-life of cut gerbera flowers

UV-C ( λ = 254 nm) irradiation was effective in reducing Botrytis cinerea floret specking (i.e., lesion development) and maintaining a better postharvest quality of cut gerbera flowers. A range of UV-C doses (0.5–10.0 kJ m −2) was tested on ‘Ice cream’ and ‘Ecco’ gerbera flowers to activate germicidal and inducible defence mechanisms. Irradiation of B. cinerea cultures with 0.5, 1.0, 2.5 and 5.0 kJ m −2 UV-C resulted in up to a 10-fold reduction of conidial germination percentages and significant ( P < 0.05) delay of mycelium growth, compared to the non-irradiated control cultures. Moreover, lesion diameters on gerbera florets inoculated with UV-C irradiated B. cinerea cultures were reduced by up to 70%, suggesting that UV-C had a negative effect on the pathogenic strength of the fungi. Lesion diameters on florets of UV-C irradiated gerberas were reduced by up to 55% giving evidence that defence responses in the host tissue were induced. Concentration of total phenolics seemed to be unaffected by 0.5 kJ m −2 UV-C treatment in both cultivars, but polyphenol oxidase (PPO) activity increased and remained higher compared to the non-irradiated control flowers throughout the 48 h storage period at 20 °C. The increase of PPO suggests that this enzyme might play an important role in host defence mechanisms that suppressed B. cinerea floret specking. Gerbera flowers irradiated with 1.0 or 10.0 kJ m −2 UV-C showed improvement in vase-life by 1.8 and 2.4 d, decrease in stem break percentages by 43 and 29% and delay in stem break incidence by 3.3 and 1.3 d, respectively.

Evaluation of ethylene production by ten Mediterranean carnation cultivars and their response to ethylene exposure

Vase life is one of the most important characters of postharvest cut flower quality. The onset of ethylene production and the amount of ethylene produced by flowers vary with the carnation cultivar, and thus influence their vase life. In the present study, differences in ethylene production and the response to exogenous ethylene among carnation cultivars were evaluated. Ten different cultivars: ‘Baltico’, ‘Domingo’, ‘Exotica’, ‘Famosa’, ‘Kiro’, ‘Madame Augier’, ‘Master’, ‘Mundo’, Pilar’ and ‘Reina’were studied. Five flowers for each cultivar were exposed for 8 hours to 1 μL L–1 exogenous ethylene concentration. Ethylene production, fresh weight and water uptake was measured daily throughout theexperiments. The 10 different cultivars studied showed clear differences in vase life, ethylene production, onset timein ethylene production and response to exogenous ethylene. The shortest vase life was for ‘Exotica’ flowers which wasonly 11.6 days, while ‘Baltico’ and ‘Pilar’ lasted 2.5-3 times longer than ‘Exotica’. Most of the investigated cultivarsshowed notable increases in the amount of ethylene. However, ‘Baltico’ and ‘Pilar’ flowers produced only a traceamount of ethylene and had the longest vase life. Results showed that cultivars with a long vase life (‘Baltico’ and‘Pilar’) display high ethylene responsiveness and, in contrast, cultivars with a short vase life (‘Exotica’ and ‘Mundo’) present low responsiveness. The decline in fresh weight of cut flowers observed in the last phase of their vase life occurred earlier in short-lived cultivars than in the longer-lived ones.

Effect of GA3 and BA on postharvest quality and vase life of gerbera (Gerbera jamesonii. cv. Good Timing) cut flowers

The effect of gibberellic acid (GA3) and benzyladenine (BA) on the postharvest quality and vase life of gerbera cut-flowers was investigated. Freshly cut flower stems of gerbera cultivar ‘Good Timing’, with four outer disc florets open, were put in vases containing 0, 50, 100, 150, 200, or 300 mg·L−1 GA3 and 0, 10, 25, 50, 100, or 150 mg·L−1 of BA for 48 hr and then held in vases containing 2.5% ethanol and 3% sucrose. Vases were placed in chambers at 25°C with a relative humidity about 70% and were arranged in a Completely Randomized Design with three replicates. Data were recorded for vase life, fresh weight, solution uptake, membrane stability, total soluble solid over time and analyzed statistically. GA3 50 mg·L−1 and BA 50 mg·L−1 were the most effective treatments on vase life, fresh weight, solution uptake, membrane stability and total soluble solids of gerbera cut flowers. Cytokinins and gibberelins have potential to enhance post harvest quality of cut gerbera flowers.

Postharvest evaluation of vase life, stem bending and screening of cultivars of cut gerbera (Gerbera jamesonii Bolus ex. Hook f.) flowers

Vase life and stem bending are the main factors for evaluation of postharvest quality of cut gerbera flowers. Recently, many new gerbera cultivars with different vase life and especially stem bending have been produced. This experiment was conducted to assess the postharvest quality in 21 different important cultivars, screening and selection of cultivars have the highest vase life and the lowest stem bending as an applied and proper strategy using a basic pulse treatment (HQS 600 ppm, citric acid 300 ppm and sucrose 4%); because of very high variation in new cultivars and also cultivar dependent of stem bending in gerbera. The result showed that there are significant differences between cultivars for vase life, stem bending, ion leakage and water uptake. 'Tropic Blend', 'Cacharelle' and 'Aventura' cultivars had maximum vase life and 'Onedin', 'Ecco' and 'Entourage' had minimum vase life. Stem bending varied from 0 to 100% between different cultivars. The results led to the conclusion that screening, introducing and finally, cultivation of selected cultivars with high qualities can be used to minimize the postharvest disorders such as stem break in gerbera, and then to minimize the production costs. Key words: Cultivar screening, Gerbera jamesonii, postharvest quality, stem bending, vase life.

EFFECT OF HARVESTING TIME ON THE RESPIRATION RATE AND VASE LIFE OF THREE CUT ROSE CULTIVARS 'GOLDEN GATE', 'DUETT' AND 'CREAM PROPHYTA'

The production areas for cut flowers destined for the UK, such as in Kenya, are far from the consumption areas. This poses a challenge for growers to be able to harvest flowers at the correct stage to reach the consumer in a suitable condition. Harvest time is fundamental as it can have a major effect on final flower quality. In this study, the effect of harvesting time on the vase life and quality of cut flower stems of Rosa hybrida 'Duett', 'Golden Gate' and 'Cream Prophyta' was investigated. Flowers were dry stored at 2°C for 10 days; control flowers were placed in vases without storage. Flowers harvested in the afternoon had a lower rate of respiration - around 89 ml CO 2 /kg/h compared to 96 ml CO 2 /kg/h for morning harvested flowers. Respiration rate affected vase life; morning harvested flowers lasted 5.5 days while afternoon harvested flowers lasted 7.83 days. These results indicate how important timing of harvest is to quality and vase life.

EFFECT OF CONTROLLED IRRIGATION METHODS USING CLIMATIC PARAMETERS ON YIELD AND QUALITY OF HYDROPONIC CUT ROSES

The effects of different irrigation control methods based on climatic parameters on yield and quality of a cut rose soilless crop (Rosa 'Red France') were studied. Four control methods were evaluated: the first was based on integrated solar radiation (ISR) and performed when a preset amount of accumulated radiation (500 kJ/m) was reached; the second was based on greenhouse air temperature (GAT) and activated when 28°C threshold was exceeded; the third was regulated on internal air relative humidity (ARH) and activated when values dropped 50% threshold; the fourth was a time clock program (TCP, control). Irrigation control methods did not affect the production of cut stems (average 19.7 stems/plant in all four treatments). ISR irrigated plants produced longer (58.3 cm) and thicker stems (8.1 mm) and were characterized by lower water supply as well higher water use and WUE than roses irrigated with other control methods. GAT, ARH and TCP were less effective and provided excessive amounts of water to the plants. ISR proved to be the most effective irrigation control system since, though more restrictive with water supply, it did not limit plant growth neither cut flower production or quality.

EFFECT OF PLANT HORMONES ON INVERTASE ACTIVITY AND ON PETAL GROWTH OF CUT ROSE

Cell expansion caused by water influx in petal cells is an important mechanism responsible for the flower opening process. It is believed that carbohydrates are key factors as an osmolite to draw water into cells. To clarify the mechanism of flower opening and to improve cut flower quality, we investigated sucrose metabolism in rose petals using attached and cut flowers. We have been probing into possibility that the quality of cut rose flowers can be improved by controlling the invertase activity in postharvest condition. In this present study, we tried to clarify the effect of plant hormones on invertase activity and on the petal growth of cut roses. First we used petal discs of Rosa 'FEbesa' for plant hormone (IAA, ABA, GA 3 , and JA) treatment. The results showed that IAA and GA 3 could increase the activity of cell-wall bound invertase, and IAA, GA 3 , and ABA increase that of vacuolar invertase. For applied experiments with plant hormones, we used a scent rose Rosa 'Meivildo', which has a short vase life. We found some of the plant hormones (IAA and JA) in vase solution affected the petal growth of cut rose. For example, flower opening was promoted by NAA treatment and delayed by JA treatment compared with control. We are now investigating about sugar metabolism including invertase activity in rose petal on each treatment.