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Jo Ann Robbins and Patrick P. Moore

During storage for 16 days at 0 or 4.5C or storage for 8 days at 20C, fresh raspberry (Rubus idaeus L. var. idaeus) fruit became darker, less red, and more blue as recorded in L* a* b* CIE coordinates. Cultivars maintained their relative at-harvest ratings throughout storage. Rates of change for cultivars during storage did not differ. Color changes depended on temperature, with rates of change fastest at 20C, especially during the first 4 days. Fruit stored 16 days at OC was more red and less blue than that stored at 4.5C. Maximum color change was reached after 8 days at 0 or 4.5C and after 4 days at 20C.

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Patrick P. Moore

Cultivated raspberries may include North American red raspberry (Rubus idaeus strigosus Michx), European red raspberry (R. idaeus vulgatus Arrhen.) or black raspberry (R. occidentalis in their pedigrees. Twenty-one raspberry clones were investigated using chloroplast restriction fragment length polymorphisms to determine the cytoplasm type and the amount of cytoplasmic diversity among these selected clones. The raspberry clones were selected representing North American red raspberry, European red raspberry, black raspberry and cultivars with divergent maternal lineages. Total cellular DNA was probed with two 32P-labelled fragments of tomato chloroplast DNA. Probe-restriction enzyme combinations were selected which discriminated between representatives of the two red raspberry subspecies. Raspberry clones were grouped according to the chloroplast restriction fragment patterns. The composition of the groups was compared with their pedigrees.

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P.G. Braun, P.D. Hildebrand, and A.R. Jamieson

Twenty-five cultivars of red raspberry (Rubus idaeus L.) and one purple raspberry (R. occidentalis L. × R. idaeus L.) were evaluated for their resistance to fire blight caused by Erwinia amylovora (Burr.) Winslow et al. Actively growing raspberry cane tips were wound inoculated with three isolates of the pathogen and disease development was assessed over 17 days. Three methods of evaluating resistance were used: area under the disease progress curve (AUDPC), a weighted AUDPC called the area under the disease severity curve (AUDSC), and lesion length. A wide range of resistance levels was observed, but no cultivars were symptomless. Primocane-fruiting cultivars tended to be more resistant than floricane-fruiting ones. Of the three E. amylovora isolates used in this study, one was significantly more virulent than the other two, but no cultivar × isolate interaction was detected.

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Patrick P. Moore

Randomly amplified polymorphic DNA markers (RAPDs) were used to distinguish among seven Pacific Northwest red raspberry (Rubus idaeus L.) cultivars. Random 10-base sequences were used to distinguish among `Chilcotin', `Chilliwack', `Comox', `Meeker', `Qualicum', `Tulameen', and `Willamette'. The seven cultivars could be distinguished even though there is considerable relatedness among the cultivars. `Chilliwack' and `Comox' share `Skeena' as a parent, and `Chilliwack' is a parent of `Qualicum'. `Willamette' is a parent of `Meeker'. This technology shows promise as a means of distinguishing cultivars and developing a genetic map to aid in breeding.

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John R. Clark and James N. Moore

Seeds of 25 blackberry (Rubus spp.), five red raspberry (R. idaeus L.), and two black raspberry (R. occidentalis L.) populations that had been stored for 22 to 26 years were planted in the greenhouse to evaluate their germination. Germination ranged from 0% to 84% among all populations. Thorny and thorny × thornless blackberry populations had the highest average germination; most populations had >40% germination. Thornless blackberry populations ranged from 1% to 16% germination. The seeds of two of the five red raspberry populations did not germinate and none of the black raspberry seeds germinated.

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Ribo Deng and Danielle Donnelly

Labeled (`“C) compounds were recovered from tissue disks taken from 14CO2-fed leaves of l-year-old greenhouse-grown plants and l-month-old ex vitro transplants of red raspberry (Rubus idaeus L.) by hot (boiling in 80% ethanol immediately after 14C exposure), delayed-hot (boiling in 80% ethanol after a 2- to 3-day ethanol soak), and room-temperature (RT) (2-to 3-day soak in 80% ethanol) extraction methods. The RT extraction method was simple but as effective for extracting 14C-labeled compounds from red raspberry leaf tissues as hot and delayed-hot extraction methods.

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T.C. Vrain, Hugh A. Daubeny, J.W. Hall, R.M. DeYoung, and A.K. Anderson

The inheritance of resistance to the root lesion nematode [Pratylenchus penetrans (Cobb) Filip. and Stek.] in red raspberry (Rubus idaeus L.) was studied in a four-member half diallel, involving two resistant genotypes and two susceptible genotypes. Estimates of general and specific combining abilities (GCA and SCA, respectively) were determined for nematode densities in roots alone and soil alone, nematode densities per plant, and plant root and foliage biomass. GCA were significant for nematodes in soil and for root and foliage biomass; SCA were significant for nematodes in the soil and for root biomass. Neither GCA nor SCA was significant for number of nematodes in the roots or per plant.

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Patrick P. Moore and Jo Ann Robbins

A crumbly fruited clone of `Centennial' red raspberry (Rubus idaeus L.) had fewer drupelets per fruit and smaller fruit than normal-fruited `Centennial'. Although there was more abortive pollen in the crumbly clone of `Centennial', there was no difference in drupelet set between the two `Centennial' clones when used as paternal parents. Thus, in `Centennial', the mechanism causing crumbly fruit was primarily a maternal effect. There was no evidence of disease as a cause of the crumbly fruited `Centennial' clone and observations were consistent with a somatic mutation.

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Jean-Guy Parent and Danièl Pagé

Characterization and identification of 13 red raspberry (Rubus idaeus L.) and two purple raspberry (R. × neglectus Peck) cultivars were obtained by nonradioactive genetic fingerprinting. DNA from leaves was digested with Hae III and Hin f I restriction enzymes and probed with alkaline phosphatase-labeled oligonucleotide. All tested cultivars could be identified by a unique band pattern. No differences were noted within cultivars when the reproducibility of the fingerprints was evaluated by analyzing the effects of age of the raspberry plantation, developmental stage during the growing season, or position of the sampled leaf on stem. These results suggest that simple nonradioactive DNA fingerprinting can be routinely used to identify raspberry cultivars.

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J.G. Carew, K. Mahmood, J. Darby, P. Hadley, and N.H. Battey

The effects of temperature, photosynthetic photon flux density (PPFD) and photoperiod on vegetative growth and flowering of the raspberry (Rubus idaeus L.) `Autumn Bliss' were investigated. Increased temperature resulted in an increased rate of vegetative growth and a greater rate of progress to flowering. Optimum temperatures lay in the low to mid 20°C range. Above this the rate of plant development declined. Increased PPFD also advanced flowering. While photoperiod did not significantly affect the rate of vegetative growth, flowering occurred earliest at intermediate photoperiods and was delayed by extreme photoperiods. These responses suggest that there is potential for adjusting cropping times of raspberry grown under protection by manipulating the environment, especially temperature.