Evaluation of chilling requirements for six Arkansas blackberry cultivars utilizing stem cuttings

Woody perennial plants including blackberries (Rubus subgenus Rubus) require certain amounts of chilling or rest hours below 7ºC during the dormant season for successful bud break the following year. Arkansas-developed blackberry cultivars are being grown in various climates worldwide and all cultivars need chilling requirement estimates for accurate recommendations of adaptation. Determining chilling requirement using stem cuttings collected from field-grown plants rather than whole plants is a desirable system. We conducted a study to evaluate both artificial and field chilling of six cultivars. For the artificial-chilling study, 12- node stem cuttings were collected 2 days after the first killing frost. These were then placed in a moist medium in a walk-in cooler at 3ºC. At 100 hour chilling intervals, five cuttings of each cultivar were placed under an intermittent mist system. For the field-chilling study, a biophenometer was placed in the field to measure chill, and ten 12-node stem cuttings of each cultivar were collected at 100-hour intervals of chilling up to 1000 hours below 7ºC and placed under mist. For both studies the mist bench was located in a heated greenhouse (min. temperature of 15ºC), and cuttings were placed according to a completely random design. Budbreak was recorded weekly. Studies were analyzed separately by SAS. Results for Study One, artificial-chilling, were inconclusive due to a lack of clear differentiation among the cultivars and chilling intervals. Study Two, using field-chilling, showed a significant chilling interval x cultivar interaction. ‘Arapaho’ appeared to have a chilling requirement of 400 to 500 hours, ‘Kiowa’ 200 hours, ’Shawnee’ 400 to 500 hours, and ‘Chickasaw’ possibly 600 to 700 hours. The cultivars Choctaw and Apache did not provide clear chilling interval differentiation in the study. Our results indicate that the use of stem cuttings receiving field chilling to evaluate chilling requirement of blackberry cultivars has merit and can be a successful method in this research area

Horticultural Studies 1999

Horticultural Studies 1999 is the second edition of a Research Series dedicated to horticultural programs in the University of Arkansas Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Sciences. This publication summarizes research, extension, and educational activities that serve horticultural industries and interest groups in Arkansas. The goals of this publication are to provide relevant information to the growers and end-users of horticulture crops in Arkansas and to inform the citizens of Arkansas and the surrounding region of activities related to horticulture

Determination of Chilling Requirement of Arkansas Thornless Blackberry Cultivars

Little research has been done to determine the chilling requirement for blackberry cultivars. However, field observations from areas where fewer hours of chilling occur indicate that ‘Navaho’ requires more hours of chilling than does ‘Arapaho’. The objective of our study was to determine a method for measuring the chilling requirement using whole plants of two blackberry cultivars, Arapaho and Navaho. One-year old, bare-root plants were field-dug on 26 October 1999 and placed in a cold chamber at 3ºC. Ten single-plant replications of each cultivar were removed at 100-hour intervals up to 1000 hours. The plants were potted and placed in a greenhouse (daily minimum temperature 15ºC), and plants were arranged on benches in a completely randomized design. Budbreak was recorded on a weekly basis. Data for budbreak were analyzed as a two-factor factorial (2 cultivars and 10 chilling treatments) by SAS and means were separated by least significant difference (P = 0.05). Data indicated that the chilling requirement for Arapaho is between 400 and 500 hours. For Navaho, the data indicated the chilling requirement was between 800 and 900 hours. These data support previous observations and indicate that the method used was successful in determining the chilling requirement for blackberries

Horticultural Studies 1998

Horticulture connects with people in many ways including an enhanced awareness concerning the importance of fruits and vegetables in our diet. The health benefits of such a diet is gaining wide recognition throughout the public and will likely provide tremendous opportunities for research, education and business development. Significant faculty additions and programmatic efforts were made to the university’s fruit and vegetable programs in 1998

Propagation of thornless blackberries utilizing adventitious shoots from root cuttings

Studies were conducted in early 2003 to determine the effect of root source and length on yield of adventitious shoots from root cuttings and on subsequent plant yield for University of Arkansasdeveloped thornless blackberries. In the first study, roots from ‘Arapaho’ and ‘Apache’ plants grown in an aboveground bed containing commercial potting soil were compared to field-grown roots. Bed-grown roots averaged 6.9 shoots per 15 cm root cutting while field grown roots averaged 3.4. ‘Apache’ produced more shoots/root cutting compared to Arapaho, (5.9 vs. 4.4 shoots/root cutting, respectively). In a comparison of 15- vs. 30-cm-long root cuttings of ‘Apache’, ‘Arapaho’, and ‘Ouachita’, shoot yield of 30-cm roots was higher than that of 15 cm roots, but total yield of shoots per root unit was not increased by the longer root cuttings. Rooting of adventitious shoots neared 100% in both studies, and resulting quality of plants from these shoots was very good. This minor modification to the traditional method of planting root pieces to yield individual plants could lead to a more efficient and productive yield of propagules. The use of adventitious shoots from root cuttings for blackberry plant propagation appears to be a viable method for nurserymen to consider

Adventitious shoot propagation and cultural inputs in nursery production of a primocane-fruiting blackberry selection

Studies were conducted from January to October 2005 to determine the effect of root-cutting length on adventitious shoot yield and the management practices necessary to produce nurseryquality primocane-fruiting blackberry plants. The first portion of the study measured the average number of shoots produced from 7.6 cm- and 15.2 cm-long root cuttings of APF-44 blackberry—a primocane-fruiting genotype from the University of Arkansas breeding program. Cuttings were forced in a shallow bin containing a soilless potting medium. The average number of shoots per root cutting from 7.6 cm- and 15.2 cm- long root cuttings averaged 1.6 and 2.7 shoots per root cutting, respectively. Rooting percentage for collected shoots was nearly 100% regardless of root-cutting length source. A qualitative comparison of shoots from the two roots lengths was similar. 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 with the higher rate producing larger and more attractive plants. 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

Characterization of seediness attributes of blackberry genotypes

Fresh market blackberries can feel “seedy” when consumed. This “seediness” is associated with the presence of pyrenes which are comprised of a single seed enclosed in an endocarp. Small pyrene size

Heat current rectification and mobility edges

We investigate how the presence of a single-particle mobility edge in a system can generate strong heat current rectification. Specifically, we study a quadratic bosonic chain subject to a quasi-periodic potential and coupled at its boundaries to spin baths of differing temperature. We find that rectification increases by orders of magnitude depending on the spatial position in the chain of localized eigenstates above the mobility edge. The largest enhancements occur when the coupling of one bath to the system is dominated by a localized eigenstate, while the other bath couples to numerous delocalized eigenstates. By tuning the parameters of the quasi-periodic potential it is thus possible to vary the amplitude, and even invert the direction, of the rectification.Comment: 5+3 pages 4+4 figure

Blackberry plant named `A-2524T`

Description and specifications of a new and distinct cultivar of blackberry plant originated from a hand-pollinated cross of `Ark. 2271T` (a non-patented, unreleased genotype) x `Ark. 2252T` (a non-patented, unreleased genotype). This new cultivar of blackberry plant can be distinguished by its long-shaped, large berries, good flavor, high productivity, and very healthy plants