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Pedro B. Oliveira, Cristina M. Oliveira, and António A. Monteiro

The aim of this study was to determine the effects of date of summer pruning and cane densities on growth and fruiting characteristics of the raspberry (Rubus idaeus) plant. Three summer-pruning dates (early, middle, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed to the greenhouse-grown primocane-fruiting raspberry `Autumn Bliss' in 2 consecutive years (1994 and 1995). A higher light microclimate and CO2 assimilation rate were measured within the canopy at the lowest density. Some compensation in CO2 assimilation rates were observed in the upper leaves of the high-density treatments, probably in response to low light. Delayed pruning decreased yield per cane and per row. The highest yields per cane were always observed at the lowest cane density. Densities of 16 and 24 canes/m produced the highest fruit yield. Light conditions appeared to be the most important environmental factor affecting plant productivity. Fruit were a weaker sink than roots; therefore, the role of carbohydrate reserves should be investigated.

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Kimberley Dennis, John R. Clark, and James A. Robbins

Studies were conducted from January to November of 2005 to determine the effect of root-cutting length on adventitious shoot yield and the management practices necessary to produce nursery-quality blackberry plants. The first portion of the study measured the average number of shoots produced from 7.6 and 15.2 cm long root cuttings of APF-44 blackberry—a primocane-fruiting clone (not available in commerce) from the University of Arkansas breeding program. Cuttings were forced in a shallow bin containing soilless potting media. The average number of shoots per root cutting from 7.6- and 15.2-cm-long root cuttings averaged 1.6 and 2.7 shoots per root cutting, respectively. Rooting percentage of shoots was near 100% regardless of root cutting length and produced rooted plants of equal quality. The latter part of the study included various treatments on the rooted shoots that might affect the productivity and quality of the final product intended for nursery sales in early fall. With the aim of producing a flowering/fruiting shrub by late September, three treatments were applied: pot dimension, fertilizer rate, and shoot tipping. Fertilizer rate had the greatest impact of all treatments. Above normal summer/fall temperatures may explain lack of fruiting on APF-44 blackberries, but the dimension and size of some plants provided a portion of the intended aesthetic.

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David C. Percival, J.T.A. Proctor, and J.A. Sullivan

Field experiments including supplementary trickle irrigation (IR), IRT-76 plastic film (PF), and straw mulch (STR) treatments were conducted during 1993 and 1994 to determine the influence of root-zone temperature and soil moisture status on carbon assimilation and dry mass distribution, and soil and plant nutrient content, during the establishment of Rubus idaeus L. `Heritage' primocane-fruiting raspberries. The IR, PF, and STR treatments were reapplied after the 1993 establishment year to examine their effects on an established, hedgerow planting. Physical environment, vegetative and reproductive data were collected. PF increased root and shoot mass, total flower number, and total berries harvested. Maximum leaf net photosynthetic (Pn) rates were observed under cool air temperatures and root-zone temperature of 25 °C. Field Pn measurements indicated that there was no seasonal decline in Pn. Mulch treatments however, were not beneficial to the established (i.e., 2-year-old) hedgerow planting. The root system of the 2-year-old planting was largely confined to an area within the foliage wall and also at a greater depth from the mulch treatments. Therefore, beneficial effects of mulch management on the growth and development of raspberries may be limited to the establishment year.

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C.A. Weber, K.E. Maloney, and J.C. Sanford

The performance of 11 primocane fruiting raspberry (Rubus idaeus) cultivars was evaluated based on yield and fruit weight from the first three seasons compared to the eighth and ninth seasons, respectively. Plot vigor and cane density was evaluated in the eighth season. `Prelude', `Caroline', and `Heritage' did not show a decline in yield in the eighth season compared to the first three seasons. `Kiwigold', `Graton Gold' (sold as `Goldie'), `Watson' (sold as `Ruby'), `Autumn Bliss', `Anne, and `Amity' had substantial yield decreases from early production seasons ranging from -30% to -82%. `Kiwigold' had the highest yield of 4015 kg·ha-1 (3582.2 lb/acre) in the eighth season followed by `Caroline' at 3649 kg·ha-1 (3255.6 lb/acre), `Heritage' at 3614 kg·ha-1 (3224.4 lb/acre), and `Prelude' at 3591 kg·ha-1 (3203.9 lb/acre). Fruit weight did not vary significantly among years, but there were differences among cultivars. In the ninth season, `Ruby' had the largest fruit at 3.1 g (0.11 oz), followed by `Autumn Bliss' at 2.9 g (0.10 oz), and `Caroline' and `Prelude' at 2.8 g (0.10 oz). `Summit', `Goldie', and `Rossana' had the smallest fruit at 1.5 g (0.05 oz). `Goldie' was the most vigorous cultivar and `Anne' the least in the eighth season based on vigor ratings. `Rossana' had the highest cane density at 41.6 canes/m2 (3.86 canes/ft2). Seven of 11 cultivars had cane density of 32 canes/m2 (3.0 canes/ft2) or higher, which is sufficient to produce acceptable yields in cultivars suited to the region. Overall, `Prelude', `Caroline' and `Heritage' and its sports, `Kiwigold' and `Goldie', show the most potential for long production cycles in climates similar to western New York state.

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Jose Lopez-Medina, James N. Moore, and Ronald W. McNew

Inheritance of the primocane-fruiting (PF) characteristic was studied in seedling populations of tetraploid (4x) blackberries (Rubus subgenus Rubus). Four selections (A-1836, A-593, A-830, and A-1680) and two cultivars (`Arapaho' and `Shawnee') were used as parents in a full diallel crossing scheme. Selection A-593 was used as the main source for PF due to its origin (`Brazos' × `Hillquist,' the latter an old PF cultivar). All parents except `Shawnee' have A-593 in their parentage; among the parents, only A-1836 fully expresses PF. Selfing of A-1836 resulted in 100% PF offspring, indicating that A-1836 is homozygous for this trait. Selfing of A-593, A-830, and `Arapaho' produced either a 35:1 or a 20.8:1 FF (floricane or summer-fruiting):PF segregation ratio, fitting a tetrasomic inheritance model under either random chromosome assortment (RCSA) or random chromatid assortment (RCTA), respectively, also suggesting that PF is controlled by a single recessive gene and that the parents are duplex (AAaa) for this trait. Selection A-1680 and `Shawnee' selfed did not produce PF progeny, but when crossed with the nulliplex A-1836, gave a 27:1 FF:PF ratio, indicating RCTA and that they are triplex (AAAa) for PF. According to these research, both gametic outputs (RCSA and RCTA) seem to operate in 4x blackberry. The intensity in expression of PF had a negative relationship with time to harvest, with those seedlings showing the highest PF scores producing a crop in early to mid-August. This knowledge will be helpful in implementing breeding strategies to produce PF blackberry cultivars.

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J.A. Sullivan, Weikai Yan, and J.P. Privé

Primocane-fruiting (PF) red raspberry (Rubus idaeus L.) cultivars are being grown in many regions as their popularity increases. However, testing of this perennial fruit crop is expensive and requires many years. Large genotype (G) × environment (E) interactions can make identification of superior genotypes difficult. The G/G × E (GGE) biplot can be used to measure cultivar performance and group locations into mega-environments. The GGE biplot was applied to yield trial data of three PF red raspberry cultivars Autumn Bliss, Heritage, and Redwing grown in 17 environments (year-location combinations). The 17 environments encompassed six locations in Ontario and Quebec, Canada between 1989 and 1996. `Autumn Bliss' produced the highest yields in 11 of 17 environments. `Heritage' was usually the lowest yielding cultivar. Two mega-environments were identified based on the performance of `Autumn Bliss' and `Redwing'. Some environmental variables were likely to be responsible for the discriminating ability of the test environments as they were correlated with the primary effects. The GGE biplot was an effective analysis to determine mega-environments and the cultivars best adapted to each.

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Michele A. Stanton, Joseph C. Scheerens, Richard C. Funt, and John R. Clark

We investigated the response of staminate and pistillate floral components of Prime-Jan™ and Prime-Jim™ primocane-fruiting blackberry (Rubus L. subgenus Rubus Watson) to three different growth chamber temperature regimes, 35.0/23.9 °C (HT), 29.4/18.3 °C (MT), and 23.9/12.8 °C (LT). Temperature was negatively related to flower size and morphological abnormalities in floral structures were evident in 41% and 98% of the MT- and HT-grown plants, respectively. The viability (stainability) of pollen from LT- and MT-grown Prime-Jan™ flowers exceeded 70%; that of Prime-Jim™ pollen was significantly reduced (<40%) by the MT regime. Pollen in-vitro germinability was negatively influenced by temperature but was unaffected by cultivar. LT-grown pollen held at 23.9 °C retained 63% of its original germinability over a 32-hour period; the germinability of LT-grown pollen held at 35.0 °C was decreased by 97% from its original level after 16 hours. Virtually all flowers cultured under HT conditions were male-sterile, exhibiting structural and/or sporogenous class abnormalities including petaloidy, malformation of tapetal cells, and microspores or failure of dehiscence. The duration of stigma receptivity, pistil density, and drupelet set were also negatively influenced by increasing temperature; values for these parameters of floral competency among control plants were reduced by 51%, 39%, and 76%, respectively, in flowers cultured under HT conditions. Herein, flowering and fruiting parameters and presumably the yield potential of Prime-Jan™ and Prime-Jim™ were adversely affected by increased temperature. However, assessment of their adaptative response to heat stress under field conditions awaits experimentation.

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Fumiomi Takeda and John Phillips

control followed the established bramble production guidelines for the region ( Demchak, 2006 ). A RCA trellis was installed in Fall 2001. During May and June 2008 and 2009, three primocanes per plant were bent and tied to the training wire 20 inches off

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Jean-Pierre Privé and N. Allain

Four primocane fruiting (PP) red raspberry cultivars, `Bogong', `Cascade', `Heritage', and `Dinkum', were grown in exposed or sheltered (50% permeable artificial windbreak) sites fully exposed to prevailing westerly winds. The cultivars were evaluated to determine the effects of wind stress on vegetative and reproductive development and leaf gas exchange during the establishment year. The artificial windbreak resulted in an overall 35% reduction in wind velocity, increased the number of calm days (<5.4 km·h–1) and decreased the incidence of strong breezes (>36 km·h–1). Concurrently, the artificial windbreak did not have much of an effect on altering relative humidity, air or soil temperature. All cultivars responded similarly to wind exposure Plants in exposed sites had reduced leaf areas, internode lengths, leaf, cane, and total above ground dry weights. Leaf gas exchange parameters (Pn, gs and Ci) expressed per unit leaf area did nor differ between treatments for most of the season but the sheltered plants as a whole supported a greater total leaf area and must have fixed a greater amount of carbon than the exposed plants. These larger sheltered plants produced a more extensive fruiting framework and resulted in a 2-fold yield increase. For these reasons, it is highly recommended to shelter raspberry plants from wind in the establishment year.

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Fumiomi Takeda, Kathy Demchak, Michele R. Warmund, David T. Handley, Rebecca Grube, and Charles Feldhake

primocanes on the trellis and completes much of primocane training before the fruit matures. In the fall, floricanes with their lateral canes tied to the wires may be inclined to a horizontal position and placed close to the ground by rotating the cross arms