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Abstract

To achieve an economic harvest of tomatoes mechanically under conditions of relatively high rainfall and a relatively short growing season, a new approach to field seeding was explored. Seeding of ‘New Yorker’ and ‘H 1630’ cultivars at plant populations ranging from 20,000 to 110,000 plants per acre resulted in canning yields of 24 tons per acre for ‘New Yorker’ when seeded at approximately 90,000 plants per acre with 5 rows on a 5-foot bed. Both preplant and sidedressed N as well as preplant K decreased early once-over harvest yields of ripe fruit. Conversely, the addition of these same fertility treatments, in most cases, significantly increased the once-over harvest yield of green fruit. Nitrogen resulted in a significant reduction of fruit size, while K, when it had an influence, caused an increase in fruit size. Fruit size, in most cases, decreased as plant population was increased.

Open Access

Abstract

‘Choctaw’ is the fifth in a series of erect-growing, high-quality, productive blackberry cultivars developed in the breeding program of the Arkansas Agricultural Experiment Station. Previous releases from this program are ‘Comanche’ and ‘Cherokee’ in 1974 (Moore et al., 1974a, 1974b), ‘Cheyenne’ in 1977 (Moore et al., 1977), and ‘Shawnee’ in 1984 (Moore et al., 1985). ‘Choctaw’ ripens its fruit earlier in the season than the previous cultivars, thus extending the blackberry fruiting season.

Open Access

Abstract

One objective of the Arkansas blackberry breeding program has been to develop erect-growing, thornless cultivars that produce self-supporting canes. ‘Navaho’ is the first such release from this program, and, to our knowledge, it is the first fully erect thornless blackberry to be developed worldwide.

Open Access

The southern highbush blueberry is a hybrid of Vaccinium corymbosum L. and one or more southern-adapted Vaccinium species. The southern highbush is advantageous to blueberry growers in the South since its fruit ripen 1 to 4 weeks in advance of traditional rabbiteye (V. ashei Reade) cultivars. Only limited research has been done on cultural aspects of southern highbush production. The objective of this study was to determine the optimum nitrogen rate for the southern highbush blueberry. A planting of pine straw-mulched `Cape Fear' blueberry was established in 1994 at the Southwest Research and Extension Center, Hope, Ark. Nitrogen rate treatments (0, 67, 134, 202, 269 kg·ha-1 N) were applied annually over a 3-year period (1997-99) with urea as the N source. Soil samples were taken prior to N fertilization to determine if N applied the previous year influenced current soil analysis values. Foliar elemental composition, fruit yield and individual berry weight were also determined for each treatment. Soil analysis indicated that the carryover effect of N applications from previous years was minimal. However, a possible decline in soil pH, Ca, and Mg over time at the higher N rates indicated that these variables should be closely monitored. No consistent relationship was evident between N application rate and soil nitrate. Nitrogen application rate did not have any consistent impact on yield, berry weight or foliar elemental composition. However, based on foliar N, the data indicate that N rates of 67-134 kg·ha-1 N are adequate for southern highbush in mulched culture.

Free access

The chilling requirements of the University of Arkansas blackberry cultivars Apache, Ouachita, and Prime-Jim*, and the primocane-fruiting selections APF-25, APF-27, APF-40, APF-42, APF-44, APF-46, APF-52, and APF-53 were investigated using stem cuttings from field-grown plants. A biophenometer was used to measure chilling (hours below 7 °C) in the field and 12-node cuttings of lateral shoots were taken from the cultivars every 100 hours up to 1000 hours below 7 °C. However, only 500 chilling hours had occurred at the time of this writing, and the response of budbreak to higher chilling levels could not be reported. The cuttings were placed in a mistchamber in the greenhouse with a daylength of 16 hours and air temperature of 26–29 °C. Percent budbreak was measured weekly. The cultivar × chilling interaction was significant (P = 0.05). `Apache' and `Ouachita' showed little or no budbreak up to 500 h, indicating a higher chilling requirement. The chilling requirement of Prime-Jim was determined to be between 300 h and 400 h, and that of the APF selections appeared to be between 300 h and 500 h. The chilling requirement of APF-53 could not be determined since budbreak was consistent at all levels of chilling up to 500 h. In general, the primocane-fruiting genotypes appeared to require less chilling than floricane-fruiting `Apache' and `Ouachita', and they would therefore be more suitable for low-chill locations.

Free access

Abstract

‘Saturn’ is the fourth in a series of seedless table grapes released from the grape breeding program of the Arkansas Agricultural Experiment Station. Previous releases were ‘Venus’ in 1977 (Moore and Brown, 1977), ‘Reliance’ in 1983 (Moore, 1983), and ‘Mars’ in 1984 (Moore, 1985). These cultivars are the foundation of an emerging commercial table-grape industry in the region. ‘Saturn’, a high-quality, red seedless grape with good storage and shelf-life characteristics, is expected to contribute to further expansion of the commercial industry.

Open Access

Resistance to fire blight in blackberry (Rubus subgenus Rubus Watson) was studied in both seedling populations and clonally propagated plants. Seedling populations resulted from a partial diallel crossing of seven cultivars (Apache, Arapaho, Chester Thornless, Illini Hardy, Navaho, Triple Crown, and Prime-Jim™). Clonal material evaluated included eleven cultivars (Apache, Arapaho, Chester Thornless, Chickasaw, Kiowa, Illini Hardy, Navaho, Ouachita, Shawnee, Triple Crown, and Prime-Jim) and six breeding selections. Inoculations were made by injection of suspensions of Erwinia amylovora in sterile water. Significant differences in resistance were found among genotypes; `Navaho' was the most susceptible, and `Kiowa' and a breeding selection A-2095, the most resistant. Seedling inoculations showed resistance to be quantitatively inherited and mostly additive, with an overall narrow-sense heritability of h2 = 0.32.

Free access

Leaf gas exchange of six red raspberry (Rubus idaeus L.) and one blackberry (Rubus L. subgenus Rubus Watson) genotypes growing in 12-L containers was measured at four temperatures (20, 25, 30, and 35 °C) once a month for 3 months in growth chambers by infrared gas analysis. Measurements were taken on three successive leaves on the same primocane between the third and seventh nodes (≈75% to 85% of full leaf expansion). The plants were grown in ambient (field) conditions except when measurements were taken. Maximum daily ambient temperatures rose as high as ≈37 °C during this period. Net CO2 assimilation (A), evapotranspiration (ET), and stomatal conductance (gs ) were measured during June, July, and August. Significant differences (P ≤ 0.01) in A were found among the seven genotypes. 'Arapaho' blackberry displayed the highest mean A rate at all temperatures. Only in the raspberry cultivars Nova and Reveille did the rate of A drop significantly when temperature increased from 20 to 30 °C. 'Reveille' was also the only cultivar in which A significantly declined between 30 and 35 °C. The ET increased significantly over the four temperatures in four cultivars ('Arapaho', 'Heritage', 'Nova', and 'Southland'). The ET rate at 35 °C was higher for 'Arapaho' than for all other cultivars. 'Autumn Bliss', 'Dormanred', and 'Reveille' did not change significantly as the temperature rose from 20 to 35 °C. Stomatal conductance of 'Heritage' and 'Arapaho' did not change significantly between 20 and 35 °C, whereas that of 'Autumn Bliss' and 'Reveille' declined almost 50% when temperature increased to 30 or 35 °C.

Free access