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Yoshiko Yambe, Kiyotoshi Takeno, and Takashi Saito

Seed germination percentage of multiflora rose (Rosa multiflora Thunh.) was much higher under continuous white light than in complete darkness. Red light was the most effective in inducing germination, and far-red light was ineffective. Exposure to red light for 1 min increased germination; this effect was saturated at an exposure of2 min. The red-light effect was reversed by subsequent exposure to far-red light. The results indicate that rose seeds are positively photoblastic, and that the photoreceptor involved is most likely phytochrome.

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M. Capellades, R. Fontarnau, C. Carulla, and P. Debergh

The surface structure of rose (Rosa multiflora L. cv. Montse) leaves formed in vitro under several environmental conditions (light level, relative humidity) and with various growth regulator treatments was studied by light and scanning electron microscopy. The epidermis from leaves developed in cultures grown under a higher light level and a lower relative humidity (80 μmol·s-1·m-2 and 75% RH) than the conditions used in commercial laboratories (25 μmol·s-1·m-2 and 100% RH) showed anatomical modifications of the epicuticular wax, stomata, and epidermal cells similar to that of greenhouse-grown plant leaves. These results indicate that cultured plantlets can resemble greenhouse-grown plants under modified environmental conditions. In vitro pretreatment will reduce transplant losses and shorten the acclimatization period in the greenhouse.

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Andrew D. Cartmill, Fred T. Davies Jr., Alejandro Alarcon, and Luis A. Valdez-Aguilar

Sustainable horticultural production will increasingly have to rely on economically feasible and environmentally sound solutions to problems associated with high levels of bicarbonate (HCO - 3) and associated high pH in irrigation water. The ability of arbuscular mycorrhizal fungi (AMF; GlomusZAC-19) to enhance plant tolerance to HCO3 - was tested on the growth, physiology and nutrient uptake of Rosamultiflora Thunb. ex J. Murr. cv. Burr (rose). Arbuscular mycorrhizal colonized and noninoculated (non-AMF) plants were treated with 0, 2.5, 5, and 10 mm HCO - 3. Increasing HCO - 3 concentration and associated high pH and electrical conductivity (EC) reduced plant growth, leaf elemental uptake and acid phosphatase activity (ACP), while increasing alkaline phosphatase activity (ALP). Inoculation with AMF enhanced plant tolerance to HCO - 3 as indicated by greater plant growth, leaf elemental uptake (N, P, K, Ca, Fe, Zn, Al, Bo), leaf chlorophyll content, higher mycorrhizal inoculation effect (MIE), lower root iron reductase activity, and generally lower wall-bound ACP (at 2.5 mm HCO3 -), and higher soluble ALP (at 10 mm HCO3 -). While AMF colonization (arbuscules, vesicles, and hyphae formation) was reduced by increasing HCO - 3 concentration, colonization still occurred at high HCO - 3. At 2.5 mm HCO3 -, AMF plant growth was comparable to plants at 0 mm HCO3 -, further indicating the beneficial effect of AMF for alleviation of HCO3 - stress.

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H. Brent Pemberton, Kevin Ong, Mark Windham, Jennifer Olson, and David H. Byrne

, it has spread east with the aid of Rosa multiflora , a naturalized rose species host and has become widespread from the Great Plains to the East Coast of North America ( Amrine, 2002 ). This epidemic has spread to garden roses in home and commercial

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Hiroaki Ito, Masaki Ochiai, Hiroaki Kato, Katsuhiro Shiratake, Daigo Takemoto, Shungo Otagaki, and Shogo Matsumoto

We have succeeded in establishing a virus-induced gene silencing (VIGS) of rose using Apple latent spherical virus (ALSV) vectors. An ALSV infection on rose did not cause any symptoms like those observed on other plant species and grew healthy. We have cloned and sequenced the phytoene desaturase (PDS) gene in wild rose, then used its fragment for silencing the rose internal PDS gene. The silencing phenotypes such as the highly uniform photo-bleached phenotype with PDS inhibitions were observed on the upper leaves of primary shoots and on a secondary shoot of R. rugosa for more than 5 months. ALSV vectors seemed useful for analyzing gene function and for the molecular breeding of rose.

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Genhua Niu and Denise S. Rodriguez

concentrations of leaves, stems, and roots of Rosa multiflora irrigated with saline solutions at various salinities dominated by chloride or sulfate salt for 16 weeks. Concentrations of Ca in R . odorata were similar among the treatments in all parts

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Yoshiko Yambe and Kiyotoshi Takeno

The germination percentage of Rosa multiflora Thunb. achenes was greatly increased when they were treated with 1% Driselase, a macerating enzyme, for 36 hours. The seeds germinated more rapidly when the achenes were treated with the enzyme for a longer period. Treatment with Cellulase Onozuka improved seed germination at a lower concentration than did Driselase. Pure preparations of pectinase and cellulase had effects similar to treatment with the enzymes noted. Treatment with pectinase was more efficient than treatment with cellulase. These enzymes likely loosened the bond between cells along the suture of the pericarp and forced the pericarp to split.

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Louis B. Anella*, Keith Reed, P.I. Erickson, and Janet C. Cole

Although roses have long been an important landscape plant, there is a growing interest in the use of low-maintenance roses that do not require heavy pruning or spraying. Poulsen Roser Pacific, Inc. of Central Point, Oregon, provided three plants of 48 cultivars for a trial in Stillwater, Oklahoma. The plants were produced in Oregon by grafting cultivars on seedling Rosa multiflora rootstock. Two-year-old plants were shipped bare-root to Stillwater, Oklahoma where they were planted in the field in early April, 2001. The plants were placed in three randomized complete blocks (rows) with 90 cm spacing between plants and 240 cm spacing between rows. The plants were drip irrigated as needed. During the 2002 growing season the roses were evaluated weekly for flower number, black spot, and overall quality. Four rose cultivars from Poulsen's Town and Country® series of landscape roses, Martha's Vineyard™ (`Poulans'), followed by Madison™ (`Poulrijk'), Kent™ (`Poulcov'), and Tumbling Waters™ (`Poultumb'), had the highest average flower number. Martha's Vineyard™, Kent™, and Tumbling Waters™ also rated highest among the cultivars tested for overall plant quality and black spot resistance. Other roses in the top grouping (Waller-Duncan K-ratio t test) for black spot resistance and overall quality were: Ragtime™ (`Poultieme', a climber from the Courtyard® series), Sophia Renaissance® (`Poulen002', Renaissance® series), Nashville™ (`Poulbico', Town and Country® series), Redwood™ (`Poultry', National Parks® series), Julia Renaissance® (`Poulheart', Renaissance® series), Santa Barbara™ (`Pouloesy', Town and Country® series), and Everglades™ (`Poulege', National Parks® series).

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S.M. Schneider, B.D. Hanson, J.S. Gerik, A. Shrestha, T.J. Trout, and S. Gao

Methyl bromide has been used extensively in open-field perennial crop nurseries to ensure the production of plants that are free of soilborne pests and pathogens. California regulations require that nursery stock for farm planting be commercially clean with respect to economically important nematodes. Under the terms of the Montreal Protocol, the use of methyl bromide by developed countries was phased out 1 Jan. 2005. Although the perennial nursery industry in the United States largely continues to use methyl bromide under critical use exemptions and quarantine/preshipment criteria allowed under provisions of the Montreal Protocol, nursery growers need viable alternatives to this fumigant. Two fumigation trials in perennial crop field nurseries with sandy loam and clay loam soils, respectively, were conducted to compare the efficacy of fumigants applied through standard shank-injection equipment or as emulsifiable compounds applied through drip irrigation equipment. In the garden rose (Rosa multiflora) nursery trial, nematodes were detected at planting in the untreated control, no-tarpaulin 1,3-dichloropropene + chloropicrin, and chloropicrin alone several months after treatment. Nematodes included root-knot nematode (Meloidogyne spp.) and stunt nematode (Tylenchorhynchus semipenetrans). At harvest 2 years later, root-knot nematode was detected in rose roots from untreated plots and plots treated with untarped 1,3-dichloropropene + chloropicrin, metam sodium, and chloropicrin alone. In the nut tree (Prunus spp.) nursery field trial, shank-injected treatments typically provided better nematode control than the same chemicals applied via the drip lines, although weed control and marketable trees were similar among treatments.

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Genhua Niu, Denise S. Rodriguez, and Lissie Aguiniga

the 6.0 dS·m −1 and 9.0 dS·m −1 treatments as early as 3 weeks after the treatment initiation. However, the survival rate of this rootstock was slightly higher than the other two rootstocks at the end of the experiment. Rosa multiflora had lower