Abstract
A study of the histology of the bud-graft unions involving a rose cultivar, Rosa × ‘Fire King’ and two rose understocks, R. multiflora, ‘Brooks’ and R. × ‘Manetti’, was made. These 2 combinations produce a growth phenomenon termed “brittleness”. The graft unions were characterized by large quantities of fragments of necrotic material in the understock-scion interface and delay in the reconstruction of the cambial cylinder with a corresponding decrease in thickness of the cylinders of cambial derivatives derived as a result of cambial activity.
Roses ( Rosa sp.) have been one of the most popular floral decorations for the past 5000 years and are commercially used as garden plants, cut flowers, and for food/medicinal/fragrance industrial use ( Gudin, 2000 ; Shepherd, 1954 ; Zlesak, 2006
irrigating plants based on water requirements, water use could be reduced, and plants may be acclimated for drought tolerance in the landscape ( Kozlowski and Pallardy, 2002 ). Roses ( Rosa hybrida L.) are some of the most popular garden plants in the world
We have initiated a phylogenetic study using restriction fragment length polymorphisms to examine nuclear DNA variation in a number of Rosa species. Random genomic clones were isolated from the cultivar `Confection'. To generate these clones, genomic DNA was digested with the restriction enzymes Hind III and Eco RI and the resulting fragments cloned into a pUC8 plasmid and transformed into the E. coli bacterial strain JM83. Individual clones from the DNA library were screened for polymorphism by Southern hybridization methods. Those clones displaying polymorphisms were used in combination with one, two, or three restriction enzymes to identify different size restriction fragments. Each fragment was treated as a unit character and was used to generate a phylogenetic tree using the computer program “Phylogenetic Analysis Using Parsimony” (PAUP version 3.0). Results of the studies on the amount of genetic diversity and phylogenetic affinities of Rosa species among the different sections of the subgenus Rosa will be presented.
Methods to screen for resistance to root-lesion nematode Pratylenchus penetrans in Rosa were modified to screen-rooted materials. Sixty days after rooting, plants were transplanted into 50-mL pots filled with river sand and each inoculated with 500 P. penetrans in 400 μL water 10 days later. The inoculated plants were fertilized weekly and incubated in a growth chamber or a greenhouse for 5 months when nematodes were extracted from the sand and root system and enumerated. When used for screening of the 131 Rosa accessions, this approach allowed the observation of a large variation in host suitability. While a majority of the accessions supported the multiplication of P. penetrans, previously reported resistance of R. multiflora `K1' and R. virginiana to P. penetrans was confirmed. Rosa laevigata anemoides allowed a significantly lower nematode multiplication than the currently prevalent rootstock R. corymbifera `Laxa'.
Abstract
Many rose breeders have sought the often elusive combination of plant quality and hardiness, but have had to compromise by accepting undesirable plant quality such as single flowers or large plant size to obtain hardy cultivars. The breeding program at the Morden Research Station was designed to develop hardy, attractive roses for the Canadian prairie conditions. Plants of hybrid tea and floribunda roses were used as sources of desirable foliage and flower traits. The main source of hardiness was a native prairie rose, Rosa arkansana Porter. Cultivars developed from this program are known collectively as the Parkland Rose Series (1). In the past, seedlings in the breeding program were generally large bushes, 1.5-2.0 m in height; however, in 1971 a few smaller plants 40–50 cm high were observed. ‘Morden Amorette’ and ‘Morden Cardinette’ roses were selected from this latter group and introduced by the Morden Research Station in 1977 and 1980, respectively.
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.
This study evaluated azadirachtin and imidacloprid for their ability to reduce injury by Japanese beetles [Popillia japonica (Coleoptera: Scarabaeidae)] on floribunda-type roses (Rosa sp. ‘Acadia Sunrise’), either applied to foliage or as a soil drench. Roses were arranged in field plots and exposed to resident adult beetle populations. Insecticides were evaluated in field and laboratory trials. Laboratory assays of leaves collected from plants 14 days after soil applications of azadirachtin were less preferred by adult beetles than those collected from untreated controls. Plants in field trials that received soil treatments of either imidacloprid or azadirachtin had defoliation levels that were <8% throughout the entire season, whereas untreated control plants were 20% defoliated. Addition of foliar sprays to soil applied insecticides provided no added protection to foliage. Rose blooms were more difficult to protect with both foliar and soil-applied insecticides. Bloom injury of untreated controls varied between 20% and 30%, while plants receiving soil applications of azadirachtin varied between 0.2% and 18%. Soil applications of imidacloprid provided somewhat better protection of blooms with injury ranging between 0.2% and 8%. Foliar applications of azadirachtin gave no added protection to blooms of plants treated with imidacloprid. Adding carbaryl foliar treatments every 2 weeks improved control to <2% injury, a level that was comparable to weekly application of carbaryl. The potential for using soil-applied azadirachtin to reduce the need for foliar applications of carbaryl in rose gardens is discussed.
Isozyme analysis has been used for cultivar identification, but little has been done with the genus Rosa. One hundred and sixty rose accessions (species, cultivars, and hybrids) were characterized for isozyme phenotypes using starch gel electrophoresis. Six enzyme systems were stained on three electrode buffer systems. ACP, MDH, and 6PGD were run on morpholine citrate (pH 6.1) and histidine (pH 5.7), PGI and PGM were run on histidine (pH 5.7) and lithium borate (pH 8.3), and SKDH was run on morpholine citrate (PH 6.1) and lithium borate (PH 8.3). The most variable isozymes were MDH and 6PGD. MDH and 6PGD revealed 10 and 9 bands, respectively. This study showed that isozyme variability exists in roses and can be useful in their classification into species groups.
investigated beneficial P restriction on woody nursery crops, although Hansen and Nielsen (2001) showed that P limitation reduced plant height, had no effect on flower count, and improved postproduction quality of ‘Poulbian’ Bianca Parade ® rose ( Rosa sp