Gerbera Flowers Research Articles

RESPONSE OF ASIATIC LILY (LILIUM × HYBRIDA) 'ZSA ZSA' TO CONCENTRATION OF UREA IN A CLOSED SOILLESS CULTURE

RESPONSE OF ASIATIC LILY (LILIUM × HYBRIDA) 'ZSA ZSA' TO CONCENTRATION OF UREA IN A CLOSED SOILLESS CULTURE

국내 육성 거베라의 우량묘 생산에 미치는 식물생장조절제의 영향

본 연구는 국내에서 육성된 절화용 거베라 19품종의 우량묘 생산을 위하여 적정 식물생장조절물질의 종류 및 조합을 알아보고, 국내 육성품종의 우량묘 대량생산을 위한 기초 자료로 제공하고자 실시하였다. 우량묘 생산을 위한 생장조절물질의 종류 및 조합에서 NAA와 BA의 혼용보다는 BA와 Kinetin의 흔용조건에서 대량증식이 양호하였다. 대량증식이 양호한 BA와 Kinetin의 혼용조합에서 품종에 따라 대량증식의 조건이 달리 나타났다. 19개 품종 중 대부분은 BA 1.0mg/L + Kinetin 0.5, 1.0 mg/L의 혼용조건에서 우량묘의 대량증식이 양호하였다. 그러나 '선녀', '옥샘', '피니', '핑크라이트'등 4개 품종은 BA의 농도가 높을수록 투명화묘의 발생이 많이 나타났다. 이들 품종들은 BA 0.5 mg/L + Kinetin0.1 mg/L의 흔용처리구에서 우량묘의 대량증식이 가능하였다. 생체중과 건물중은 BA 0.5 mg/L + Kinetin 0.1, 0.5mg/L 의 혼용 처리구에서 양호한 경향이었다. 엽병장에서는 전 처리구 모두 큰 차이는 없었다. 투명화묘의 조직관찰결과, 투명화묘의 기공형태는 정상묘에 비하여 기공이 열려있는 상태로 돌출되어 있었으며, 둥근 모양을 하고 있었다. This study was carried out to obtain information about the valuable combination and concentration to produce good plants of cut gerbera flowers of 19 domestically - bred gerbera cultivars. BA and kinetin combination is more effective than NAA and BA combination to produce good plants and mass propagation of domestically - bredgerbera cultivars. Normally almost of 19 cultivars, mass propagation was more effective on the medium containing 1.0 mg/L BA + 0.5, 1.0 mg/L kinetin. But some cultivars, 'Sunnyeo', 'Oksaem','Piny', and 'Pink Light', vitrified plants were induced on MS medium high level of BA concentration(BA 1.0 mg/L), in comparison with those on the medium with low level of BA(0.1 mg/L).Fresh and dry weight, more effective on the medium containing BA 0.5 mg/L . Kinetin 0.1, 0.5 mg/L. Anatomical investigation of vitrified leaf, stomata of vitrified leaves were circular and inflated, where-as those of normal leaves.

POTENTIAL OF CHLORINE DIOXIDE TO EXTEND THE LONGEVITY OF CUT FLOWERS

The postharvest longevity of fresh-cut flowers is often limited by the accumulation of bacteria in vase water and flower stems. Aqueous chlorine dioxide is a strong biocide with potential application for sanitizing cut flower solutions. We evaluated the potential of chlorine dioxide to prevent the build-up of bacteria in vase water and extend the longevity of cut Matthiola incana `Ruby Red', Gypsophila paniculata `Crystal' and Gerbera jamesonii `Monarch' flowers. Fresh-cut flower stems were placed into sterile vases containing deionized water and either 0.0 or 2 μL·L–1 chlorine dioxide. Flower vase life was then judged at 21 ± 0.5 °C and 40% to 60% relative humidity. Inclusion of 2 μL·L–1 chlorine dioxide in vase water extended the longevity of Matthiola, Gypsophila and Gerbera flowers by 2.2, 3.5, and 3.4 days, respectively, relative to control flowers (i.e., 0 μL·L–1). Treatment with 2 μL·L–1 chlorine dioxide reduced the build-up of aerobic bacteria in vase water for 6 to 9 days of vase life. For example, addition of 2 μL·L–1 chlorine dioxide to Gerbera vase water reduced the number of bacteria that grew by 2.4- to 2.8-fold, as compared to control flower water. These results confirm the practical value of chlorine dioxide treatments to reduce the accumulation of bacteria in vase water and extend the display life of cut flowers.

(39) Chlorine Dioxide Treatment Extends Longevity of Cut Gerbera Flowers

The vase life of many cut flowers is often limited by bacterial occlusion of stem bases. In this study, we tested the efficacy of a novel antimicrobial agent, aqueous chlorine dioxide (ClO2), to extend the longevity of cut Gerbera flowers by reducing the number of bacteria in vase water. Commercially mature and freshly cut Gerbera jamesonii `Monarck' flowers were placed into clean vases containing deionized water and 0, 2, 5, 10, 20, and 50 μL·L-1 ClO2. Stems were then maintained in solutions at 21 ± 0.5 °C and 42 ± 11% relative humidity until the end of vase life. Inclusion of 2, 5, and 10 μL·L-1 ClO2 in vase water had beneficial effects on flower longevity. For instance, treatment with 5 and 10 μL·L-1 ClO2 extended flower longevity by 1.4-fold or 3.7 days, as compared to control flowers (0 μL·L-1 ClO2). In contrast, exposure to the higher concentrations of 20 and 50 μL·L-1 ClO2 did not extend flower vase life. Relative to control flowers, treatment with 10 μL·L-1 ClO2 delayed the onset of detectable bacterial colonization of vase solutions from day 3 to day 6 of vase life. However, this ClO2 treatment did not reduce the number of bacteria that subsequently accumulated in vase water as compared to control flowers. Treatment with 10 μL·L-1 ClO2 also increased rates of solution uptake by stems and reduced the loss of flower fresh weight over time. These results highlight the potential use of ClO2 treatments to extend the postharvest longevity of Gerbera flowers.

A cold treatment for postharvest control of western flower thrips on strawberry runners

In 1998–99, outbreaks of Frankliniella occidentalis (Pergrande), western flower thrips (WFT), caused extensive damage to strawberry crops in the Yarra Valley, Victoria. These crops were within 30 km of Toolangi where over 80% of certified strawberry runners for Australia are produced. Commercial growers store runners for various periods of time at temperatures as low as –2°C. Cold temperature disinfestation was evaluated as a potential strategy in a contingency plan to prevent the spread of WFT on strawberry runners. Western flower thrips at various life stages on gerbera flowers (on which they were reared), were placed in small bags, made from the plastic liners used in commercial strawberry runner cartons, together with strawberry runners and exposed to –2°C for periods of 1, 2, 4, or 8 weeks. All WFT died within 4 weeks. Additional experiments were conducted in which WFT, in bags with runners or on gerbera leaf disks in petri dishes, were exposed to –2°C for 3 weeks. Only a few WFT survived these treatments; however, they were moribund. When they were assessed 2 days after completion of the exposure period, all WFT were dead. It was concluded that strawberry runners carrying WFT can be disinfested by exposing WFT to –2°C for 4 weeks and that this should be achievable under commercial conditions.

Quantitative analysis of correlations among flower traits in Gerbera hybrida, Compositae. III. Genetic variability and structure of principal component traits

A sample of 36 flower traits consisting of six morphological categories in the Davis population of gerbera was restructured into phenotypic and genetic principal component traits. The first 5 phenotypic principal component traits accounted for 62% of the total phenotypic variance of the 36 traits and have moderate to high heritablities. The first 5 genetic principal component traits account for 97% of total genetic variance and all have high heritability. Morphological structure of these component traits suggest an underlying process identified by the first genetic principal component involving largely trans and disk floret traits. The results of this study indicate that the quantitative genetic structure of the gerbera flower is controlled by a few independent components and that principal component analysis is a useful tool to reveal variation in this structure. These composite traits are heritable and are expected to respond to selection.

Variation in Pathogenicity and DNA Polymorphism Among Botrytis cinerea Isolates Sampled Inside and Outside a Glasshouse.

Colonies of Botrytis cinerea were obtained from spore samplers placed inside and outside a glasshouse with a rose crop. Pure cultures were made from five colonies collected on one sampling date every month throughout the year. These isolates were tested for germination on water agar and for pathogenicity on gerbera and rose petals. The germination rate of the conidia on water agar varied between 60 and 99%. Pathogenicity of the isolates on gerbera and rose flowers ranged from 14 to 166% relative to reference isolate Bc16 and varied among isolates collected on the same day as much as among isolates collected in different months. The pathogenicity of the isolates on rose flowers was overall higher than on gerbera flowers. Random amplified polymorphic DNA (RAPD) analysis was performed on 30 selected isolates with different relative pathogenicity, collected both inside and outside the glasshouse. Almost all of the isolates were genetically different. No correlation was found among pathogenicity, sampling time, sampling place, and RAPD patterns. Results are further evidence for the statement that B. cinerea inoculum in glasshouses continuously originates from many different sources in their vicinity.

Cutinase A of Botrytis cinerea is expressed, but not essential, during penetration of gerbera and tomato.

The plant pathogen Botrytis cinerea can infect undamaged plant tissue directly by penetration of the cuticle. This penetration has been suggested to be enzyme-mediated, and an important role for cutinase in the infection process has been proposed. In this study the expression of the cutinase encoding gene cutA of B. cinerea was analyzed using a cutA promoter-GUS reporter gene fusion. Transformants containing the fusion construct were examined for GUS expression on gerbera flowers and tomato fruits. High GUS activity was detected from the onset of conidial germination and during penetration into epidermal cells, indicating that cutA is expressed during the early stages of infection. To determine the biological relevance of cutinase A for successful penetration, cutinase A-deficient mutants were constructed by gene disruption. Pathogenicity of two transformants lacking a functional cutA gene was studied on gerbera flowers and tomato fruits. Their ability to penetrate and cause symptoms was unaltered compared to the wild-type strain. These results exclude an important role for cutinase A during direct penetration of host tissue by B. cinerea.

Comparisons of Chemical Controls for Thrips (Frankliniella occidentalis) on Greenhouse-grown Gerbera (Gerbera jamesonii L.)

Chemical and physical methods were tested to determine their effectiveness in controlling Western Flower Thrips, Frankliniella occidentalis (Pergande), in greenhouses. Comparisons were made between abamectin (Avid); Spinosyn A and D, formulated from the soil Actinomycete, Saccharopolyspora spinosa (Spinosad); azadirachtin (Margosan-O); and diatomaceous earth, a physical control aimed at deterring pupation. Results based on the number of thrips counted in gerbera (Gerbera jamesonii L.) flowers indicate that the chemical treatments were significantly more effective in reducing populations than the diatomaceous earth. Over time, the population of thrips in both the Avid and Spinosad treatments was reduced to zero. Diatomaceous earth treatments reduced populations almost 50% as compared to the control, while reductions from Margosan-O ranged 50-90%.

Microscopical studies of the infection of gerbara flowers byBotrytis cinerea

The formation of lesions on ray florets of gerbera flowers caused by single conidia ofBotrytis cinerea was studied in two cultivars infected by two isolates of the pathogen. No differences in reaction after inoculation with conidia of either isolate were seen on either cultivar. The conidia produced usually one germ tube not longer than 10 μm, but conidia with five germ tubes were also seen. Direct penetration of germ tubes through the upper cuticle of ray florets was observed. No appressoria or other specialised structures were observed before penetration, and degradation of the cuticle did not occur. Germination of conidia and subsequent flower infection was dependent on the availability of free water, but not on the addition of external nutrients.

Complex segregation analysis of Gerbera flower colour.

The distribution of hue (CIELAB colour notation) classes among flowers of the Davis population of gerbera (Gerbera jamesonii H. Bolus ex Hooker) appears bimodal. This suggests that the genetic control of hue is determined by the segregation of a gene with large effect modified by additional genes with smaller effects. Complex segregation analysis (CSA), routinely employed in human genetic epidemiology, was used to study both qualitative and quantitative variation. CSA applies pedigree analysis through the consideration of transmission probabilities to optimize likelihood functions of various genetic models. Applying this technique to study flower hue of a sample representing generations 14, 15 and 16 of the Davis population, allowed identification of a putative dominant major gene with genotypic values for the dominant homozygote, heterozygote and recessive homozygote of 32, 32 and 71 degrees, respectively. This corresponds to the modes of the hue frequency distribution for the population. The putative major gene represents 0.66 of the total variation. The residual parent-offspring correlation (rho po = 0.2) measures the genetic contribution to the remainder of the variance.

Yield and quality of carnation ( Dianthus caryophyllus L.) and gerbera ( Gerbera jamesonii L.) in a closed nutrient system as affected by sodium chloride

To study the consequences of NaCl-containing irrigation water in closed nutrient systems, effects of increasing NaCl concentrations up to 30 mM on yield and quality of spray carnation and gerbera were investigated. In carnation, salinity decreased peduncle length at 23 mM NaCl. In the less salinity-tolerant gerbera, number of flowers, flower weight and flower area were decreased with 8 mM NaCl. Post harvest vase-life was not affected by salinity. As a similar yield decrease occurred in a treatment which had an increased salinity using increased concentrations of major elements, it is concluded that specific ion-toxic effects of Na + and/or Cl − were not related to the yield decrease. Chemical analysis of peduncles of carnation or gerbera flowers showed no consistent effects of NaCl on concentrations of major elements. Influx concentrations of Na + were linearly related to the concentration in the nutrient solution. On average, influx was 2.5% and 7% of the Na + concentration in the nutrient solution for carnation and gerbera, respectively. The consequence is that Na + accumulates in the nutrient solution more rapidly for carnation than for gerbera. Influx concentrations of Cl − were higher, and non-linearly related to the Cl − concentration in the nutrient solution. Average electrical conductivity (EC) needed to compensate for uptake of minerals was 0.7–0.8 dS m −2.

COMPLEX SEGREGATION ANALYSIS (CSA) OF GERBERA FLOWER COLOR

The frequency distribution of gerbera flower hue in the Davis population of gerbera appears continuous and bimodal. This suggests that a gene of large effect may be segregating in a background of polygenic variation. CSA is a statistical technique developed in genetic epidemiology for investigating such complex traits without the need of inbred lines. The REGC program of SAGE (Elston, LSU Medical Center, New Orleans) uses the regressive models of G. Bonney (1984) through pedigree analysis to provide estimates of major gene parameters and residual correlations among relatives. Pedigrees obtained from generations 14, 15, and 16 indicate that a major dominant gene for hue is segregating and accounting for -0.66 of the total variation. The genotypic means are 32 degrees and 71 degrees for the aa and bb genotypes, respectively. The a allele is dominant to the b allele and has a frequency of 0.55. The residual parent-offspring correlation estimate is 0.2 and measures the genetic contribution to the remainder of the variance.

Effects of temperature, vapour pressure deficit and radiation on infectivity of conidia ofBotrytis cinerea and on susceptibility of gerbera petals

The effect of vapour pressure deficit, temperature and radiation on the postharvest susceptibility of gerbera flowers toB. cinerea, on the water relations of gerbera flowers and on the lesion formation after conidial infection ofB. cinerea was studied. The temperature range in whichB. cinerea could germinate and growin vitro is 5–30 °C. In climate chamber experiments flowers had more lesions ofB. cinerea at temperatures of 20 and 25 °C than at 10 and 15°C. At 15, 20 and 25°C the infectivity ofB. cinerea conidia was negatively affected during a storage-period of 7 days. At a vapour pressure deficit (VPD) of 200 Pa significantly more conidia ofB. cinerea were infective than at 800 Pa. At a VPD of 800 Pa the susceptibility of gerbera flowers forB. cinerea was not significantly different than at 200 Pa. High radiation levels in glasshouses in spring and summer negatively influenced the infectivity of conidia ofB. cinerea on the flower surface, but did not affect the susceptibility of gerbera flowers forB. cinerea. In spring and early summer conidia lost their infectivity at high radiation levels, high temperatures and high levels of VPD. In summer gerbera flowers could be more susceptible toB. cinerea because of high temperatures in glasshouses, but the negative effect of radiation on the conidia ofB. cinerea seemed to overrule the temperature effect. Thus, the numbers of lesions in spring and summer can be low compared with the numbers in other seasons, although the numbers ofB. cinerea colonies on spore traps can be high. The effect of temperature on the susceptibility of gerbera flowers can probably be explained by changes of water status in the petals. At higher temperatures the number of lesions and the turgor (=water potential—osmotic potential) in the petals increased. Temperatures 95% and VPD<50 Pa) had a temporary negative effect on the number of lesions. After 3 days of incubation the numbers of lesions were about equal (≥30 lesions/cm2) from 5 to 20°C. At 30°C no lesion formation was observed even after 3 days.

050 Complex Segregation Analysis (CSA) of Gerbera Flower Color

The frequency distribution of gerbera flower hue in the Davis Population of Gerbera appears continuous and bimodal. This suggests that a gene of large effect may be segregating in a background of polygenic variation. CSA is a statistical technique developed in genetic epidemiology for investigating such complex traits, without the need of inbred lines. The REGC program of SAGE (Elston, LSU Med. Center, New Orleans) utilizes the regressive models of G. Bonney (1984) through pedigree analysis to provide estimates of major gene parameters and residual correlations among relatives. Pedigrees obtained from generations 14, 15, and 16 indicate that a major dominant gene for hue is segregating and accounting for ∼ 0.66 of the total variation. The genotypic means are 32 degrees and 71 degrees for the aa and bb genotypes, respectively. The `a' allele is dominant to the `b' allele and has a frequency of 0.55. The residual parent-offspring correlation estimate is 0.2, and measures the genetic contribution to the remainder of the variance.

Effect of Bacteria on Scape Bending in Cut Gerbera jamesonii Flowers

Including bacteria in the vase water of cut Gerbera jamesonii Bolus flowers resulted in an increase in scape curvature depending on the concentration of bacteria in the water, cultivar, and season. In the summer, a strain of Pseudomonas aeruginosa or a mixed population of bacterial species, all isolated from the vase water of cut gerbera flowers, resulted in curvature of &gt;90° in `Liesbeth' at 108 cfu/ml and in `Mickey' at 1010 cfu/ml. In winter, the lowest bacterial concentrations that resulted in such bending were 106 and 108 cfu/ml, respectively. `Mickey' showed bending at a lower water potential than `Liesbeth'. Comparison between these results and the bacterial counts in vase water and water at retail shops indicates that frequently observed scape bending is at least partly due to bacteria.

Monoclonal Antibodies-Based Immunofluorescence Test for Detection of Conidia ofBotrytis cinereaon Cut Flowers

Whole conidia, their extracellular material, and a putative cutin esterase isolated from conidia of Botrytis cinerea were used as antigens to raise monoclonal antibodies (MAbs) for the detection of conidia of B. cinerea. Using immunofluorescence, three selected MAbs recognized conidia of 43 isolates of B. cinerea from hosts representing six countries. The percentage of conidia that fluoresced ranged from 50 to 100%. Intensity of fluorescence was related more to the MAb than to the Botrytis isolate tested. MAbs showed no reaction with healthy gerbera flowers or to spores produced by other common airborne fungi and bacteria. Crossreaction with conidia of four other species of Botrytis occurred, but their fluorescence patterns differed from those of conidia of B. cinerea

Influence of environmental conditions on dispersal of Botrytis cinerea conidia and on post‐harvest infection of gerbera flowers grown under glass

Dispersal of Botrytis cinerea in a gerbera crop grown in two glasshouses 30 km apart was studied over a period of 18 months, in 1988 and 1989. Conidia were caught in spore traps consisting of agar in petri dishes exposed at different heights in the crop in each glasshouse. No seasonal patterns could be identified in the spore catches, assessed as colonies on the agar traps after incubation. The number of lesions caused by conidial infection of gerbera flowers following incubation, however, showed a distinct pattern. In spring and early summer few lesions were recorded whereas at other times of the year many lesions appeared. In linear regression analysis, variation in numbers of colonies (spore catches) could not be explained by environmental factors recorded during the experiments. Linear regression accounted for 77% and 81% of the variation in the number of lesions on flowers in the two glasshouses, in terms of relative humidity (postively correlated), global radiation outside the glasshouse (negatively correlated) and age of the crop (positively correlated). Despite differences in the systems by which the gerbera crop was produced and in the spore catches, the numbers of lesions on gerbera flowers in the two glasshouses were significantly correlated though not significantly different from each other.

Effects of temperature, relative humidity and age of conidia on the incidence of spotting on gerbera flowers caused by Botrytis cinerea

In recent years, spotting of ray florets of gerbera flowers has become an important problem. This type of small necrotic lesions may occur before, but especially shortly after harvesting the flowers.Botrytis cinerea was easily isolated from such lesions.

Response of Cut Gerbera Flowers to Fluoridated Water and a Floral Preservative

Abstract Twenty gerbera (Gerbera jamesonii H. Bolus, ex Hook f.) cultivars were evaluated for longevity in deionized water (DI), deionized water containing 1 mg fluoride (F)/liter, and deionized water containing 200 mg 8-hydroxyquinoline citrate (8-HQC) + 20 g sucrose (S)/liter. Flowers of different cultivars differed in fluoride sensitivity. Sensitive cultivars developed necrosis on the tips of ray florets within 12 to 24 hr of exposure to fluoridated water, whereas the least-sensitive cultivars were injured within 4 to 6 days. Petal necrosis was the prim ary factor reducing longevity in fluoridetreated flowers. Petal necrosis did not occur on flowers held in DI or 8-HQC + S. The mean postharvest lives of the 20 cultivars held in fluoridated water, DI, and 8-HQC + S were 2.6, 5.3, and 8.3 days, respectively.