Cut Roses Research Articles

Compatibility of Orius insidiosus (Hemiptera: Anthocoridae) with Amblyseius ( Iphiseius) degenerans (Acari: Phytoseiidae) for control of Frankliniella occidentalis (Thysanoptera: Thripidae) on greenhouse roses

The compatibility of two commercially-marketed natural enemies of Frankliniella occidentalis (Pergande), an anthocorid bug, Orius insidiosus (Say), and a phytoseiid mite, Amblyseius (= Iphiseius) degenerans Berlese, was tested on cut roses, Rosa hybrida L. cv. ‘Tropicana’. Our goal was to determine the extent to which intraguild predation could affect suppression of F. occidentalis by this predator complex. We conducted laboratory experiments to examine: (1) effects of prey densities, prey composition, and crop structure on predation by adult O. insidiosus, (2) prey switching behavior in O. insidiosus, and (3) effects of Orius gender on prey preference. We found that Orius insidiosus will switch to the more abundant prey if presented with variable ratios of adult A. degenerans and immature or adult F. occidentalis on flowers or foliage. If presented with prey in equal numbers, O. insidiosus preyed more on A. degenerans than adult F. occidentalis but equally on A. degenerans and immature F. occidentalis. Males and females of O. insidiosus showed similar patterns of predation, but females killed more prey than males. In greenhouse trials simulating thrips infestations of cut rose crops, we compared control of F. occidentalis on roses with releases of both O. insidiosus and A. degenerans or only O. insidiosus. Roses with or without predators produced similar numbers of harvestable flowers, but roses with predators had fewer thrips than roses without predators. Releases of both predators did not enhance thrips control because roses with both predators had similar numbers of thrips as roses with only O. insidiosus.

PREDATORY MITES FOR BIOCONTROL OF THE GREENHOUSE WHITEFLY, TRIALEURODES VAPORARIORUM IN CUT ROSES

Integrated Pest Management (IPM) is successfully used on a year-round scale on only 15% of the area of roses under glass. Obstacles for further expansion of IPM practices among rose growers are the control of the spidermite Tetranychus urticae and the greenhouse whitefly Trialeurodes vaporariorum. The research stations of Naaldwijk, Aalsmeer and Boskoop have started initiatives in order to enlarge the choice of predator species available for Dutch growers. A series of greenhouse experiments were conducted to select phytoseiid mites suitable for commercial cut roses. Among ten species tested in experimental greenhouses, Euseius ovalis was found to be the most promising control agent of T. vaporariorum. Its efficacy against other pests and its compatibility with chemicals are the subject of further studies. Since E. ovalis is an exotic species formerly not commercially available, efforts are being made to obtain authorization for experimenting with this species in commercial greenhouses in the framework of new fauna protection regulations in The Netherlands.

THE EFFECT OF TEMPERATURE ON YEAR-ROUND DEVELOPMENT OF ROSE SHOOTS INITIATED USING CUTTING OR BENDING

The development of greenhouse-grown cut roses (Rosa hybrida ‘Kardinal’ and ‘Fire ‘N Ice’) in relationship to temperature was tracked during nine cycles of growth from December 2003 to May 2005. Hourly leaf canopy air temperatures were monitored continuously and used to compute the accumulated thermal units to each of five developmental stages. During cycles 1-3 all shoots on a plant were cut back, while during cycles 4-7 shoots were cut back or bent to initiate a new flush of shoot growth. For cycle initiation via cutting versus bending there was a significant difference in the thermal units required for development in only one of the four cycles. Results suggest that a thermal unit model developed for ‘Kardinal’ or ‘Fire ‘N Ice’ can be applied whether cutting or bending is used for shoot initiation. The thermal units from cycle initiation to harvest were greatest during cycles 1 and 2 (750-770), significantly less for cycles 5 and 6 (680-700) and least during cycles 3, 6, and 7 (615-625) for ‘Fire ‘N Ice’. For ‘Kardinal’ the thermal units required from cycle initiation to harvest were 680700 for cycles 1, 2, and 7 when mean daily light integral was less than 17 mol m -2 d -1 . While for cycles 3 to 6, the accumulated thermal units to harvest was significantly less, averaging 615 °C d -1 when mean daily light integral ranged from 20 to 33 mol m -2 d -1 . In cycles 8 and 9 plants were grown under 3 light levels to test different hypotheses on factors causing seasonal variation in thermal units. The effects of increasing light were largely explained by temperature at shoot level rising proportionally greater than temperature recorded within the leaf canopy. A software program has been developed to aid in rose crop scheduling which uses projected greenhouse temperatures to schedule when cycle initiation and other developmental events should occur.

C-Pro (grapefruit seed extract) as supplement or replacement against rose- and cucumber powdery mildew

Numerous fungicide applications are often needed to control powdery mildews in greenhouse-grown crops, and consequently there is an increasing demand for alternative means to control them. In commercial greenhouses, attack of powdery mildew caused by Podosphaera xanthii in cucumbers and P. pannosa in cut roses was controlled by weekly sprays of C-Pro CE601, a dilution of grapefruit seed extract (GSE). The raw material of GSE, delivered by Citricidal®, is a glycerolic extract from seed and juiceless pulp of grapefruits (Citrus paradise). In both cultures C-Pro at 2000 ppm achieved as good control as treatments with penconazole or triforine. The mean level of attack by powdery mildew on leaves of cut roses one week after the last of three weekly treatments, was 9.8, 12.9 and 40.5% for penconazole, C-Pro (2000 ppm), and untreated, respectively. In cucumbers, there was less difference between the untreated control and the different treatments, but for all times of assessments, C-Pro and triforine were better than untreated (p=0.001). There was no significant difference in cucumber between C-Pro and triforine. Phytotoxicity symptoms such as leaf twisting and rolling in roses (cv. Jade and Cezann) and dark green leaves and indications of growth retardation in cucumbers (cv. Ventura) were observed at the higher concentrations used (3000–4000 ppm). Thin layer chromatography of C-Pro CE601 has previously shown presence of benzethonium chloride, a synthetic antiseptic agent. Further research is necessary to determine if the observed effects of the product tested are due to natural compounds or are merely due to a synthetic preservative agent added. Our results revealed that C-Pro might be a supplement or even a replacement to some of the current fungicides used against powdery mildew.

IPM program successful in California greenhouse cut roses

We developed and tested an integrated pest management (IPM) program for the key pests of cut roses, which was based on fixed precision sampling plans, thresholds, biological control, directed sprays of reduced-risk pesticides, and cultural control. This program represented the largest effort to date to implement an IPM program in U.S. floriculture. The biological control of mites was successful at all locations, and pesticide use was generally lower in the IPM greenhouses. Future work will concentrate on reducing scouting time, improving natural-enemy release methods, and developing IPM techniques for secondary pests and powdery mildew.

Multivariate Analysis of Relations between Preharvest Environmental Factors, Postharvest Morphological and Physiological Factors, and Vase Life of Cut ‘Asami Red’ Roses

Rose (Rosa hybrida L.) ‘Asami Red’ plants were grown in a glasshouse for a year and the preharvest environmental parameters, and morphological and physiological parameters of individual cut flowers at harvest and during the postharvest period were recorded. Principal component analysis showed interrelations between the parameters: rose plants grown under “dry” conditions, i.e., high temperature, low relative humidity, and consequent high vapor pressure deficit, produced cut flowers having delayed wilting symptoms, resulting in a long vase life; cut roses with a high transpiration rate in the dark at harvest could not maintain their water relations properly, resulting in a shorter vase life; roses grown under “dry” conditions had small stomata and a low transpiration rate in the dark at harvest. These results indicate that humidity conditions are key preharvest environmental factor affecting the vase life of cut roses, and roses grown under “dry” conditions develop more functional stomata, regulate their water relations properly after harvest, and have a longer vase life. Multiple regression analysis to predict the vase life from preharvest environmental parameters and morphological and physiological parameters at harvest generated a significant equation (Y = −0.0971·X1 + 0.0242·X2 − 0.3275·X3 − 2.84792·X4 − 0.4859·X5 + 15.397, where Y is the number of days of vase life; X1−X5 are the daily minimum relative humidity, ratio of the stem diameter of the neck and cut end, stomatal width, water potential in the light, and transpiration rate in the dark, respectively; R2 = 0.618; P < 0.001).

Vascular blockage in cut roses in a suspension of Pseudomonas fluorescens

SummaryTo analyse quantitatively the relationships between cut rose (Rosa hybrida L. ‘Pascha’) vase-life, the onset of cavitation, plant water potential, and bacterial concentrations in the vase water, rose stems were placed in water containing different concentrations of Pseudomonas fluorescens 2892 tetr rif r. There was a significant correlation (P = 0.0009) between cut rose vase-life and the concentration of bacteria in the vase water. As the number of bacteria in the vase water increased, the rate of senescence also increased. The water potential for roses in the bacterial suspension (at 8.50 log10 CFU ml–1) proceeded to drop constantly after 5.17 h in the vase solution, with the water potential falling to as low as -2.35 MPa by the end of the experiment (at 117 h). In contrast, the water potential of roses in deionised water dropped from -0.419 MPa at 5.17 h, to only –0.663 MPa after 117 h. When roses were stood in a bacterial suspension (at 8.5 log10 CFU ml–1) for 30 h, 63.8% of the total cumulative cavitation events were seen, while roses stood in deionised water exhibited only 26.8% of the total cavitation events. Uptake of acid fuchsin and the movement of tagged P. fluorescens 2892 in the xylem indicated that bacteria did not travel beyond the open-ended xylem vessels and were generally restricted to the first 50 mm from the cut end of the stem.

Research on Optimum Greenhouse Utilization for the Production of Cut Rose Flowers : How to Secure Agricultural Income before the Price Increase of Heavy Oil A for Heating

Research on Optimum Greenhouse Utilization for the Production of Cut Rose Flowers : How to Secure Agricultural Income before the Price Increase of Heavy Oil A for Heating

Analysis of sucrose metabolism during petal growth of cut roses

To clarify the mechanism of flower opening, we investigated sucrose metabolism in rose petals using attached and detached flowers. The petal fresh weight of sucrose-treated detached flowers was lower than for attached flowers, and hexose levels of these detached-flower petals were also lower. Invertase activities in attached flowers increased markedly during petal growth, but these activities in detached flowers decreased, even when detached flowers were treated with sucrose. These different invertase activities might be the cause of the different growth between attached flowers and sucrose-treated detached flowers. Our results suggest that inducing invertase activity in postharvest conditions might be important for the quality of some rose cultivars.

QTL analysis of variation for vigour in rose

The improvement of energy efficiency in the greenhouse production of cut rose and pot rose can be achieved through the use of rose cultivars having vigorous growth. A better understanding of the inheritance of vigour and its related traits will assist the breeding activities. Quantitative trait locus (QTL) analyses were performed with the help of an integrated linkage map of a diploid rose population originating from a cross between Rosa multiflora-derived genotypes. The underlying datasets for ten vigour-related traits were collected in an evaluation study of this population in two greenhouse experiments with suboptimal temperatures for growth. We identified ten chromosomal regions, scattered over the seven linkage groups, containing QTLs for these traits. Considering each trait separately, we detected a total of 42 QTLs. Among these QTLs, 24 were found in both of the experiments, eight and ten were specific to either of the two experiments. The number of QTLs for individual traits varied from three to five with a respective contribution to the phenotypic variation from 12 to 35%. QTLs for highly correlated traits frequently co-localized, indicating a common genetic basis. Clustering of QTLs for different traits was noted in some chromosome regions, for instance, one on chromosome 2 included major QTLs for eight of ten traits under study, suggesting co-localization of several separate genes or/and the occurrence of various genes having pleiotropic effects. The discovery of markers associated to QTL regions is in roses the first step towards marker-assisted selection for vigour improvement enabling the transfer of useful QTL-alleles of R. multiflora to pot and cut roses.

Powdery mildew resistance in roses: QTL mapping in different environments using selective genotyping

Podosphaera pannosa, the causal agent of rose powdery mildew, hampers the production of cut roses throughout the world. A major tool to control this disease is the use of resistant plant material. Single resistance genes, like Rpp1, may be overcome within a few years by high risk pathogens like powdery mildews. Durable resistance could be achieved using quantitative resistances. Here we describe mapping of QTLs for resistance to P. pannosa in six different environments (artificial and natural infections in the greenhouse over 3 years and natural infections in the field over 2 years). AFLPs, RGAs and other marker types were used to construct an integrated linkage map for the diploid population 97/7 containing 233 markers. In a selective genotyping procedure, marker segregation was analysed for 170 of the up to 270 phenotyped individuals. We identified seven linkage groups with an average length of 60 cM, corresponding to seven rose chromosomes in the haploid set. Using an LOD significance threshold of 3.9 we detected a total of 28 QTLs for the nine powdery mildew disease scores under analysis. Using the data from artificial inoculations with powdery mildew race 9, three resistance QTLs explaining about 84% of the variability were mapped. Twelve and 15 QTLs were detected for resistance to naturally occurring infections in the greenhouse and in the field, respectively, over several years.

Introdução de novas cultivares de rosas no Brasil.

New rose variety introductions in Brazil. In 2002 researchers, government representatives, and rose growers met in Fortaleza (Ceará) with the objective of translating rose documents from UPOV. This meeting marked the first step in protection of new rose varieties developed in Brazil, inserting that flower into the Varieties Protecting Law. Five years later many new rose varieties were registered and protected in Brazil. There are many positive aspects that have developed during that time. A trust with Brazil occurred with breeders and international rose producers such as: Nirp International and Melland from France, Tantao from Germany and Holland, Preesman, Lex, D´Rouiters and Schuers. This occurs through participation in the Hortitec Fair every year in Holambra (São Paulo). The introduction of new Brazilian varieties has fostered an interest in improving the production, logistics and postharvest process of fresh cut roses. Brazilian named rose varieties such as Ipanema, Copacabana, Senna, Carioca and Bahia were recognized in the last edition of Hortifair transforming these varieties into international commercialized brands, therefore bringing recognition to the Brazilian market. The Brazilian rose market is one of the biggest of the world. The efforts of the breeders union, growers and other members from commercial chains will increase the number of high quality roses. Therefore it is necessary that the governmental agencies support to Intellectual Propriety Rights of breeders and enforce laws that the illegal propagation and commercialization of protected material.

Leaf Area Index, Water Index, and Red: Far Red Ratio Calculated by Spectral Reflectance and its Relation to Plant Architecture and Cut Rose Production

In roses (Rosa ×hybrida L.), the bending of branches is a technique that modifies the canopy of the plant and could affect such parameters as the leaf area index (LAI), the quality of reflected light, and the water index (WI) of the plant. The measurement of spectral reflectance with remote sensors is a nondestructive, quick, and simple method to study these parameters. The aim of this paper is to quantify the modification of reflected radiation quality, the LAI and the water index of the plant with different canopies, and its impact on flowering and the number and quality of flowers produced. In R. ×hybrida `Terracotta', using the spectral crop reflectance, the red: far red ratio [red (R) = 680 nm; far red (FR) = 730 nm], percentage of blue light of reflected radiation, and vegetation indices [normalized difference vegetation index (NDVI), simple ratio index (SRI), water index (WI)] were calculated in two architectural managements: traditional (upright hedge) and bent shoot. NDVI had a greater correlation with LAI than SRI (r2 = 0.98 and 0.85, respectively), but SRI was more reliable for LAI values of 1 to 3.5. The bent shoot system compared to the traditional one decreased the R:FR ratio of reflected radiation and increased LAI and plant water content. These changes were related to a higher commercial quality of the flowers (longer flowering shoots with a larger stem diameter and fresh weight), although there was no significant difference in the number of flowers harvested. The period that showed the largest difference in the quality of the flower using the bent shoot system had a LAI of 2.8 vs. 1.8 with traditional management and a marked reduction in the R:FR of the light reflected by bent plants. The bent shoot system advanced the peak production by 1 month at the end of winter and improved the flowers at a time when sun radiation is limiting factor for production.

Extension of the Vase Life in Cut Roses by Treatment with Glucose, Isothiazolinonic Germicide, Citric Acid and Aluminum Sulphate Solution

Cut rose (Rosa hybrida L.) cv. Rote Rose was treated with glucose, fructose or sucrose at 10 g L-1 in combination with a commercial preparation of isothiazolinonic germicide (a mixture of 5-chloro-2- methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one; CMI/MI; Legend MK) at 0.25, 0.5 or 1 mL L-1. To stabilize germicidal activity, the solution was acidified by the addition of citric acid to a final concentration at 30 mg L-1. Of the sugars, glucose was the most effective in extending the vase life, followed by fructose. CMI/MI was most optimal at 0.5 mL L-1. The addition of aluminum sulphate at 50 mg L-1 to glucose plus CMI/MI considerably extended the vase life of cut roses more than glucose plus CMI/MI. Based on these results, a formulation comprising 10 g L-1 glucose, 0.5 mL L-1 CMI/MI, 30 mg L-1 citric acid and 50 mg L-1 aluminum sulphate was designated as GLCA and the effect of GLCA on the vase life of 8 cultivars was compared against 10 g L-1 glucose plus 200 mg L-1 8-hydroxyquinoline sulphate (HQS). Treatment with GLCA extended the vase life of all the tested cultivars more than glucose plus HQS. Hydraulic conductance of stem segments in the control ‘Rote Rose’ roses decreased rapidly after harvest, but those for GLCA and glucose plus HQS were maintained at near their initial levels. The extension of vase life in cut roses by the addition of GLCA is attributed to the supply of sugars and the suppression of vascular occlusion without toxicity to cut flowers.

Influences of Preharvest Relative Humidity on Yield, Vase Life and Transpiration of Cut Roses

Rose plants (Rosa hybrida L. ‘Asami Red’) were grown hydroponically at 25°C in a 12-h day and 20°C in 12-h night cycle. The preharvest relative humidity (RH) was set at constant 60% or 85% for a constant humidity experiment, and 60 (day) /85 (night) % or 85 (day) /60 (night) % for a altered humidity experiment. The cut flower yield was greater at the constant high RH condition of 85% than at the constant low RH of 60%. Cut flowers grown at 85% RH had larger stomata in the dark than those at 60% RH. The cut roses grown at 85% showed high stomatal conductance even in the dark and poorly responded to light-dark alternation, resulting in increased transpiration and consequent decreased vase life. In altered humidity experiment, the cut flower yield was higher at 85/60% RH than at 60/85% RH. Stomatal size, responses of stomata to light-dark alternation, daily transpiration and vase life of cut flowers did not differ significantly between these two RH treatments and were almost similar to those of the roses grown at constant 60% RH. Cyclic control of day-night RH is an effective means to achieve both high yield and long vase life of cut roses.

Study on the Optimum Utilization of Greenhouses for the Production of Cut Roses by Year-round Cutting

Study on the Optimum Utilization of Greenhouses for the Production of Cut Roses by Year-round Cutting

Effects of the Temperature of Vase Water on the Vase Life of Cut Rose Flowers

Cut rose (Rosa hybrida L.) ‘Sonia’ flowers were placed in vases of which water temperatures were kept at 10, 15 and 23°C under constant air temperature of 23°C. Vase life of cut roses became longer with lowering water temperature; the vase life was 5.2, 6.7 and 7.5 days at 23, 15 and 10°C, respectively. Fresh weight of cut flowers increased over the first 3, 4 and 5 days during the experimental period at 23, 15 and 10°C, respectively and decreased thereafter. Temperature of flower part was very slightly lowered by lowering water temperature. Hydraulic conductance of stem segments decreased on the third day after harvest, and this decrease was suppressed by lowering the temperature of vase water. Bacterial number in vase water increased with time, and this increase was suppressed by lowering the temperature of vase water. These results show that low temperature of vase water might improve the stem water relation and extended the vase life of cut rose flowers.

SEASONAL CARBOHYDRATE AND TOTAL NITROGEN DISTRIBUTION IN ROSE PLANTS: DEVELOPMENTAL AND GROWTH IMPLICATIONS

SEASONAL CARBOHYDRATE AND TOTAL NITROGEN DISTRIBUTION IN ROSE PLANTS: DEVELOPMENTAL AND GROWTH IMPLICATIONS

NUTRIENT UPTAKE OF CUT ROSES GROWN ON SUBSTRATE

NUTRIENT UPTAKE OF CUT ROSES GROWN ON SUBSTRATE

MODIFIED ATMOSPHERE PACKAGING (MAP) FOR PRESERVING GERBERA, LILIUM AND ROSA CUT FLOWERS

Cut flowers often have a short vase life. Over a few days after harvest, petal decolouration, tissue browning, loss of flower parts and total senescence usually occurs. These events will significantly compromise their commercial value. A modified atmosphere packaging system is proposed to increase flower vase life. Some preliminary tests on different cultivars of Gerbera, Lilium and Rosa were carried out to individualize the best gas mixture to introduce in the package. Three different mixtures were compared: air (78%N2/21%02/0.03%C02) and two without oxygen (100%N 2 and 90%N 2 /10%CO 2 ), plus a non-packaged control. Packages were preserved at 4±1°C and flowers subsequently analyzed after 3, 6, 9 and 12 days of storage. Gerbera 'Dino' and 'Igloo' cut stems had a longer vase life when packaged in air compared to the non-packaged control. Lilium cut stems packaged for three days in a modified atmosphere had a similar vase life to that of the control. In our experiments, cut roses were more perishable than Gerbera and Lilium cut stems. This was possibly associated with the high greenhouse temperatures that rose flowers experienced during the summer harvest. Although we established that modified atmospheres may significantly extend cut flower vase life, it still remains to verify the species- and cultivar-specific effects of packaging on flower vase life.