. ‘Twilight’ is expected to be adapted to areas where other semi-erect blackberries (e.g., ‘Chester Thornless’, ‘Triple Crown’) can be grown successfully. A U.S. Plant Patent has been granted (USPP 30,879) ( Finn, 2019 ). Origin ‘Twilight’, tested as ORUS 4370
Chad E. Finn, Bernadine C. Strik, Brian M. Yorgey, Mary E. Peterson, Patrick A. Jones, Jungmin Lee, Nahla V. Bassil, and Robert R. Martin
Chad E. Finn, Bernadine C. Strik, Brian M. Yorgey, Mary E. Peterson, Patrick A. Jones, Gil Buller, Sedat Serçe, Jungmin Lee, Nahla V. Bassil, and Robert R. Martin
‘Triple Crown’ and better than ‘Chester Thornless’ ( Table 2 ). In general, the semierect and erect blackberries show more symptoms of heat damage than do the trailing types. Although we cannot rule out a genetic component to this, we suspect it is largely
Jose Lopez-Medina and James N. Moore
An experiment was carried out to investigate whether detached segments of floricanes during winter pruning of erect blackberries could be used as a source of propagating material. Portions of lateral branches from `Arapaho', `Navaho', `Choctaw', and `Shawnee' field-grown plants, subdivided according to their position on the cane (tip, middle, and base), and treated with or without 0.3% IBA in talc were stuck in peat—perlite mix under intermittent mist in greenhouse conditions. Differences in percentage of cuttings rooted occurred only for cultivars; `Arapaho' rooting the highest (99%) and `Shawnee' the lowest (83%). IBA improved volume of roots formed. Cultivar by position interaction effect was evident for volume of roots, percentage survival of cuttings after potting, percentage shoot formation, and dry weight of shoots and roots, with highest values for stem cuttings taken from the middle of canes of `Arapaho' and lowest for basal cuttings of `Shawnee'. `Choctaw' stem cuttings produced the largest shoots regardless of their position or treatment with IBA. These findings suggest that propagation of erect blackberries by floricane stem cuttings is feasible. This work might be useful to plant breeding, either for early collection of pollen or in controlled pollinations.
John R. Clark and James N. Moore
Yield and average berry weight were measured for first year fruiting (on semi-erect canes) and second year fruiting (erect canes) to compare harvest age effect for erect blackberries established from root cuttings. cultivars were `Cheyenne', `Choctaw', `Navaho' and `Shawnee' and 4 plantings were included in the comparison. One of the four plantings had an average yield of 27% more in the first year as compared to the second year. The other plantings had higher yields in the second year as compared to the first ranging up to a 100% increase. Yield was 23% higher for the second year when all plantings were averaged. Average yield increase by cultivar in the second year compared to the first was: 'Choctaw' 37%, 'Cheyenne' 27%, 'Navaho' 22% and 'Shawnee' 20%. Berry weight was not affected by harvest age except in one planting, where average weight was higher for first year fruiting.
Jose Lopez-Medina and James N. Moore
In an early study we reported the feasibility of propagating erect blackberries by floricane cuttings obtained during winter pruning. But how soon during the dormant season can the stem cuttings be collected? And, is a mist system really needed to promote rooting? Experiments were conducted to address these questions. Stem cuttings of `Arapaho', `Choctaw', and `Shawnee' blackberries were collected on two dates, 15 Nov. and 15 Dec. 1996, stuck in peat-perlite mix, and placed in two rooting environments, with and without intermittent mist. Data was recorded on 15 Jan. 1997. Percentage of cuttings rooted was affected by the cultivar-by-date and cultivar-by-environment interactions. Values of 98%, 88%, and 75% were observed for cuttings taken on 15 Dec. of `Choctaw', `Arapaho', and `Shawnee', respectively, while only 19%, 17%, and 45%, respectively, for cuttings of 15 Nov. Intermittent mist promoted higher rooting (85% vs. 31% without mist) and lower death of cuttings (4% vs. 45% without mist) only of `Shawnee'. Greater number of cuttings died when taken on 15 Nov. (21%) than on 15 Dec.(6%). These findings suggest that accumulation of chilling units is an important factor to take into consideration when propagating blackberries by floricane cuttings.
P. Perkins-Veazie, J.K. Collins, and J.R. Clark
Fruit at three stages of ripeness were harvested from four erect blackberry (Rubus spp.) cultivars, `Navaho', `Choctaw', `Cheyenne', and `Shawnee', for 2 years to evaluate fresh-market shelf life during 7 days of storage at 2C, 95% relative humidity. Ethylene production was highest from dull black fruit and varied widely among cultivars, ranging from 7.3 to 51.1 pmol·kg–1·s–1 for `Navaho' and `Choctaw' fruit, respectively. Weight loss ranged from 0.8% (`Shawnee') to 3.3% (`Navaho') after storage. Mottled (50% black) fruit of all cultivars were higher in fruit firmness and titratable acidity and had lower soluble solids and anthocyanin concentrations than fruit at other stages of maturity. Cultivars did not differ in total anthocyanin concentration, but dull black fruit had a higher anthocyanin concentration than shiny black fruit. Dull black `Choctaw', `Shawnee', and `Cheyenne' fruit were softer and had more leakage and decay than shiny black fruit. Both shiny and dull black `Navaho' fruit had less leakage than fruit of other cultivars. All cultivars at the shiny black stage were considered marketable after 7 days at 2C because fruit were firm with little decay or leakage. However, red discoloration appeared more frequently on shiny black than on dull black fruit. Mottled fruit of erect cultivars should not be harvested, while shiny black fruit of `Cheyenne', `Shawnee', and `Choctaw' might be suited for regional markets. Either shiny black or dull black `Navaho' fruit could be shipped to distant markets.
P. Perkins-Veazie, J.K. Collins, and J.R. Clark
P. Perkins-Veazie, J.K. Collins, E. Baldwin, and Fumi Takeda
Erect-fruited blackberries are often described as having a wild blackberry flavor. Flavor can be greatly affected by sugar and volatile composition, neither of which is known for erect-fruited blackberries. This study was done to characterize changes in sugar and volatile composition in ripening blackberries. Blackberries of `Navaho', `Arapaho', `Shawnee', and `Choctaw' were harvested at red, mottled, shiny, and dull black ripeness stages. Sucrose was found in small amounts (4% to 15%) in all stages of ripeness in all cultivars. Total sugars increased from ≈20–30 to 60–80 mg/g dry weight as fruit ripened from red to dull black. Fructose and glucose maintained a constant 1:1 ratio with ripeness stage and cultivar. Three of the four cultivars had a linear increase in total sugars with ripening; total sugars increased 4% to 40% as fruit ripened from shiny to dull black. Twenty to 25 volatile peaks were found by headspace gas chromatography in ripening blackberries. Six volatiles, tentatively identified as α-pinene, eugenol, limonene, p-cymene, α-terpinol, and gernaylacetone, appeared in all cultivars, but only in ripe (shiny and dull black) fruit. Few volatile peaks were observed in red (unripe) fruit. Data indicate that blackberries continue to increase in sugars in the latter stages of ripeness and that volatiles unique to ripe blackberries are produced during this period.
Michele R. Warmund and Joan Krumme
The time of rest completion of `Apache', `Arapaho', `Chickasaw', `Darrow', `Kiowa', `Navaho', and `Shawnee' blackberry (Rubus subgenus Rubus Watson) buds was compared and various models for estimating chilling were evaluated. `Kiowa' and `Arapaho' buds had the shortest rest periods, while those for `Shawnee', `Navaho', and `Chickasaw' buds were intermediate. `Apache' and `Darrow' buds had the longest rest periods. The model that accounted for the variation in percent budbreak among cultivars and temperatures during two dormant periods had the following two components: 1) a chilling inception temperature of –2.2 °C and 2) weighted chilling hours that accumulated after the chilling inception temperature. The chilling hours in this model were weighted as follows: 0 to 9.1 °C = 1; 9.2 to 12.4 °C = 0.5; 12.5 to 15.9 °C = 0; 16 to 18 °C = –0.5; >18 °C = –1. This study also elucidated that a blackberry model with a chilling inception temperature of –2.2 °C estimated chilling more accurately than one with chilling inception just after the maximum negative accumulation of chill units as used in the Utah chilling model. Also, temperatures between 0 and 2.4 °C must be weighted more heavily in a blackberry model than in the Utah peach model to accurately estimate chilling and rest completion.
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.