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Horacio E. Alvarado-Raya, Rebecca L. Darnell, and Jeffrey G. Williamson

Interest in off-season production of red raspberry ( Rubus idaeus L.) is increasing as a result of the high demand for a limited supply ( Darnell et al., 2006 ; Knight et al., 1996 ; Pritts et al., 1999 ; Schloemann, 2001 ) and the resultant

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Justine E. Vanden Heuvel, J. Alan Sullivan, and John T.A. Proctor

Treatments of either staked (stabilized) or not staked (control, freestanding) canes were applied to Rubus idaeus L. `Boyne' and `Regency' during the 1997 and 1998 seasons to determine the effect of stabilizing fruiting canes in a windy environment. Treatments were applied in late April of each year, and canes were removed following harvest for growth analysis. Stabilizing (staking) floricanes increased yield per cane in `Boyne' by 68% and in `Regency' by 189%, primarily through increases in fruit number per cane. Leaf area of the staked canes was 41% larger for `Boyne' and 159% for `Regency' than that of the control canes, suggesting that more leaf area was retained for photosynthesis, resulting in greater yield. Primocane diameter in `Boyne' and primocane height in `Regency' were also increased by staking, but floricane structure was unaffected.

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Jianfeng Liu, Bowen Yang, Yuetong Ming, Yuchu Zhang, and Yunqing Cheng

Rubus idaeus is a red-fruited species of Rubus L. and has remarkable economic and cultural value. This genus is distributed over both the hemispheres and is commonly cultivated in temperate regions ( Sønsteby and Heide, 2009 ). Its berry has

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Helena Mathews, C. Cohen, W. Wagoner, J. Kellogg, V. Dewey, and R. Bestwick

We have developed efficient plant rageneration and transformation systems for red raspberry (Rubus idaeus L.). We have successfully introduced a gene for controlling biosynthesis of ethylene into raspberry for the first time. Leaf and petiole segments were co-cultivated with disarmed Agrobacterium strains EHA 101 or 105 containing plasmids pAG5420, pAG 1452 or pAG1552. The plasmids encoded gene sequences for S-adenosylmethionine hydrolase (SAM ase) driven by the fruit specific or wound and fruit specific tomato SE8 or E4 promoters. SAM ase catalyses the conversion of S-adenosylmethionine (SAM) to methylthioadenosine (MTA) and homoserine which can reenter the methionine recycling pathway. SAM is therefore not available for the synthesis of 1-am inocyclopropane carboxylic acid (ACC), the metabolic precursor for ethylene biosynthesis. Initial shoot regenerants were mostly chimeras containing transformed and non-transformed cells. Solid clones of pure transgenics were developed by repeated culture of leaf, petiole and nodal explants of primary regenerants on higher stringency selection medium. Transformants were screened on medium with kanamycin, geneticin or hygromycin depending on the selection marker gene NPTII or hpt. Genomic integration of transgenes were confirmed by Southern hybridization. Transgenic plants of cultivars Canby, Meeker and Chilliwack have been transplanted to the greenhouse for fruit set and further evaluation of transgenic traits.

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David C. Percival, John T.A. Proctor, and J.P. Privé

Rubus idaeus L. cv. Heritage raspberries were placed in controlled environment chambers (25°C, 14-hour photoperiod, 2.0 kPa vapor pressure deficit, CO2 concentration of 380 mol·m-2·s-1) to study the effects of drought stress on leaf gas exchange and stem water potential. Whole-plant photosynthesis (Pn) and transpiration were sensitive to drought stress and gradually decreased from the second day of the study until rehydration. Stomatal aperture feed-back regulation was present during the initial 48 hours of the study with transpiration rates dropping in response to a decrease in stem water potential. Spatial differences were also present with leaf Pn, and stomatal and CO2 conductance values of the younger, distal (i.e., closer to the apex) leaves decreasing at a faster rate than the older, proximal leaves (i.e., close to crown). Evidence of increased mesophyll resistance to drought stress was apparent with ci either remaining constant or increasing, while Pn and carboxylation efficiency simultaneously decreased. Protection of the underlying photochemistry was evident with parahelionastic leaf movements which resulted in a reduction in the effective leaf area and subsequent heat load. Therefore, an optimum balance between water loss and ci existed, and an alteration in these rates represented a stomatal conductance adjustment to match the intrinsic photosynthetic capacity rather than just a causal relationship.

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Brenner L. Freeman, Janet C. Stocks, Dennis L. Eggett, and Tory L. Parker

cultivar, across the season, and between storage treatments. Materials and Methods Raspberry collection. Six cultivars of Rubus idaeus L. raspberries (‘Autumn Bliss’, ‘Caroline’, ‘Jaclyn’, ‘Joan J’, ‘Polana’, and ‘Polka’) grown on a 20 acre farm in Utah

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Jean-Pierre Privé, J.A. Sullivan, and J.T.A. Proctor

Leaf removal, cane girdling, and 14C translocation patterns were used to study source-sink relationships of primocane-fruiting (PF) red raspberries. Although the leaves in the reproductive zone were most important for vegetative and reproductive development, compensatory effects between the cane leaves were evident. When 14C translocation was studied in the reproductive portion of the cane, the lateral closest to the 14C-treated leaf was the major sink for carbohydrate from that leaf, independent of leaf position or reproductive development. Thereafter, partitioning to leaves and/or flowers or fruits above the 14C-treated leaf was related to leaf phyllotaxy 75% of the time.

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Stephen F. Klauer, J. Scott Cameron, and Chuhe Chen

With the advent of new rotary-head mechanical harvesters, it is now possible to machine-harvest a wider raspberry canopy. In Spring 1996, a trial was established in a grower's field in Lynden, Wash., comparing raspberries trained to two top wires with a 70-cm spread (split trellis) to the conventional single top wire system. Within the split trellis, increases in leaf number per cane (97%), and leaf area per cane (55%) were not reflected in a concomitant increase in total leaf dry weight per cane (35%). Leaf dry weight per fruit weight was 11% less within the split trellis. These data suggest that the canopy is more efficient with this type of trellis. Increases in estimated yield per cane (49%) and projected yield per acre (50%) associated with the split trellis were due to increases in berry number per cane (47%). Fruit number per meter of lateral was 35% greater within the split trellis. Greatest enhancements to yield components were in the upper parts of the canopy where canes were tied over. Since there were no differences in lateral numbers or lateral lengths between the two systems, this increased productivity was due to increased floral expression, enhanced fruit set, increases through Spring bud initiation or any combination thereof. In both trellis systems, the longest laterals occurred on the middle third of the cane and decreased in length progressively towards the tip of the cane. Primocane lengths were shorter (20%) and diameters were smaller (10%) and more uniform in the split trellis system.

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Regina L. Reickenberg and Marvin P. Pritts

The dynamics of nutrient uptake from foliar applied 15N-urea and Rb (a K analog) were quantified in red raspberries. Both N and Rb in an aqueous solution were absorbed rapidly into the leaf and transported throughout the plant. In the greenhouse, about half of the urea and a third of the Rb were absorbed within 32 hours of application. The addition of a surfactant to the foliar solution reduced uptake, while solution pH, time of application and leaf age had little effect. The lower leaf surface exhibited a faster rate of absorption than the upper surface, but the difference was not large. In the field, some foliar N appeared to have been washed off leaves and taken up by the root system; however, none of the foliar applications affected plant growth. We conclude that significant uptake of foliar applied N and K occurs in raspberry, but the absolute amount delivered through a single foliar application is small. The percentage of total plant nutrient supplied through a foliar application is reduced to < 5% over time as the plant grows, so multiple applications would be required to maintain levels significantly higher than would exist through root uptake alone.

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Patrick P. Moore and Rita L. Hummel

Days to bud break and freezing tolerance of `Chilcotin', `Chilliwack', `Meeker' and `Willamette' red raspberry were measured during the 1990-1991 winter and at monthly intervals from mid-September 1991 through mid-March 1992. Canes were harvested from the field and cut into two-bud samples which were either frozen in laboratory tests or held with cut stem ends in water in a controlled environment chamber and monitored daily until bud growth was observed. Viability was estimated by visual browning after exposure to controlled laboratory freezing treatments. In general, freeze test results indicated `Meeker' and `Willamette' were not as hardy as `Chilliwack' and `Chilcotin' in late fall and midwinter but retained their hardiness longer in spring. Results for 1990-1991 indicated the greatest delay in days to bud break occurred in midwinter.