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

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

Selective wear of cuttings elements of working organs of tillage machines with realization of self-sharpening effect

The clause of strengthening of cuttings elements is conditioning and realization of such selforganization process as a self-sharpening. Sharpening of horizontal and vertical cuttings elements of working organs of tillage machines (CE WOTM) is considered in many works, but not found out the terms of realization and nature of these processes in a sufficient measure. The processes of sharpening and blunting of CE WOTM are related mainly to the processes of wear. The change of type of CE in the process of wear is conditioned mainly a size and character of tearing down each of its bevel and by volume of destruction of cutting edge in the process of exploitation in the medium of soil and depends on character of co-operation in tribosystem " WOTM -soil"

Frontier exploration and the North Atlantic Igneous Province : new insights from a 2.6 km offshore volcanic sequence in the NE Faroe–Shetland Basin

Acknowledgements and Funding This work was funded by Chevron. The authors would like to acknowledge the Chevron West of Shetlands team along with the Joint Venture partners OMV, Faroe Petroleum and Indemitsu for access to data along with permission to publish this study. PGS is thanked for access to the Corona Ridge Regional Geostreamer (CRRG) data and permission to publish the seismic line. The paper was improved thanks to insightful reviews by S. M. Jones and A. Saunders, which substantially improved an earlier draft. J. Still and F. Thompson gave invaluable technical support at the University of Aberdeen, and K. Wall helped with real-time cuttings analysis.Peer reviewedPostprin

Testing of pear trees on their own roots in comparison with important used rootstocks under organic farming conditions with special regard to fire blight (E. amylovora)

Pear trees on their own roots are tested in comparison to grafted trees in growth and yield characteristics and with special regard to the tolerance to diseases, above all fire blight (Erwinia amylovora). In spring 2004 15 randomized trees of the cultivar 'Williams' from three variants (self rooted in vitro, self rooted long cuttings, grafted on Quince A) were planted in a pear orchard, which was heavily infected with fire blight (Erwinia amylovora) the previous years. The trees were left untreated. Growth and yield characteristics, plant diseases and tree losses were observed. After four years the in vitro self rooted trees were significantly more vigorous in growth than those grafted on quince A. The self rooted long cuttings were comparable in growth with grafts on quince, but showed high tree losses probably due to frost damages in the first winter one year after planting. However no infections with Erwinia amylovora could be observed so far. In a field trial with more cultivars and rootstock variants planted in 2006 at two organically managed sites more significant effects are expected in the next years