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Bernadine C. Strik and Gil Buller

fruiting season by ≈1 week compared with untipped canes. Date of tipping during the growing season has affected yield and fruiting season of primocane-fruiting blackberry ( Drake and Clark, 2003 ) and raspberry ( Rubus idaeus ) ( Jordan and Ince, 1986

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John R. Clark and James N. Moore

Seeds of 25 blackberry (Rubus spp.), five red raspberry (R. idaeus L.), and two black raspberry (R. occidentalis L.) populations that had been stored for 22 to 26 years were planted in the greenhouse to evaluate their germination. Germination ranged from 0% to 84% among all populations. Thorny and thorny × thornless blackberry populations had the highest average germination; most populations had >40% germination. Thornless blackberry populations ranged from 1% to 16% germination. The seeds of two of the five red raspberry populations did not germinate and none of the black raspberry seeds germinated.

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Gina E. Fernandez, James R. Ballington, and Penelope Perkins-Veazie

‘Von’ is a new floricane-fruiting blackberry ( Rubus L. subgenus Rubus Watson) released by North Carolina State University. ‘Von’ is a productive plant with high yield, late harvest season, excellent postharvest attributes, and small seed size

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Kim E. Hummer and Derek N. Peacock

Recent USDA plant collecting expeditions to Ecuador; the People's Republic of China, and within North America, have obtained a number of lesser known wild Rubus species. These, and additional species, are preserved as seedlots with some plant representatives, at the USDA-ARS National Clonal Germplasm Repository-Corvallis. In this study, the seed size of 40 Rubus species was measured and contrasted. The average weight of the largest-seeded species of the study group, R. megalococcus Focke, an Ecuadorean blackberry, was 24.2 mg; European blackberry, R. procerus Muller, was 3.0 mg. The average weight of other European and North American blackberry and raspberry seed ranged from 2.7 to 1.3 mg. Asian raspberry species tended to be the smallest, ranging from R. coreanus Miq. at 1.2 mg to R. eustephanus Focke ex Diels at 0.3 mg. Several of the smaller seeded Asian species such as R. formosensis Kuntze, R. minusculus A. Leveille & Vaniot, R. hirsutus Thunb., and R. eustephanus had many drupelets, which may be a heritable trait to benefit yield through breeding for increased fruit size.

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David Mettler and Harlene Hatterman-Valenti

Blackberry (Rubus subgenus Rubus Watson) production has the potential to expand into the northern Great Plains with the development of the rotating cross-arm (RCA) trellis system that prevents winter injury by laying the plants horizontal to the ground so that they can be covered during cold periods. However, this will only occur with the evaluation of new cultivars and overwintering protection methods associated with the RCA trellis system. Ten cultivars under four rowcover treatments were evaluated for winter damage, vegetative growth, yield, and fruit quality. Thermo-couples monitored air temperature under each rowcover treatment. Results indicated that rowcovers differed in their ability to moderate winter air temperatures. However, temperature moderation differences from rowcovers did not correspond to plant growth differences. Instead, cultivar influenced plant growth differences. Plants under the thermal blanket with corn stover had greater yield and more berries, while fruit quality was unaffected by rowcover treatment. Differences were also found between cultivars for fruit quantity and quality. Although rowcovers enabled overwintering primocanes to produce fruit after winter temperatures reached −30 C, further research is recommended to improve winter protection techniques and the identification of higher-yielding floricane blackberry cultivars for production in the northern Great Plains.

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Renee H. Harkins, Bernadine C. Strik, and David R. Bryla

Commercial production of blackberries ( Rubus L. subgenus Rubus , Watson) has increased rapidly in recent years from a total of 13,960 ha worldwide in 1995 to 20,035 ha in 2005 ( Strik et al., 2007 ). Approximately 6000 ha are currently produced

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Creighton Gupton

Anthocyanin deficient dewberry (Rubus trivialis Michx.) clones with translucent ripe fruit and green canes were studied to determine their possible utilization as a source of marker genes for blackberries. Albino dewberries from two locations designated Bonnette (BON and Harriel (H) were crossed with each other and with normal dewberry (DB). F1 plants were testcrossed. DB X H produced 62 plants all of which had red canes. BON X DB produced 59 plants all of which had red canes. BON X H produced nine plants all of which had green canes. The segregation ratio of each testcross supported the hypothesis that anthocyanin deficiency in dewberry is controlled by a single recessive gene. A recessive allelet known to cause a very low concentration of anthocyanin, giving fruit with yellow color and stems with non-pigmented spines, is probably responsible for the mutant trait. Its simple inheritance provides potential for anthocyanin deficiency to be used as a marker gene.

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Justine E. Vanden Heuvel, J. Alan Sullivan, and John T.A. Proctor

Treatments of either staked (stabilized) or not staked (control, freestanding) canes were applied to Rubus idaeus L. `Boyne' and `Regency' during the 1997 and 1998 seasons to determine the effect of stabilizing fruiting canes in a windy environment. Treatments were applied in late April of each year, and canes were removed following harvest for growth analysis. Stabilizing (staking) floricanes increased yield per cane in `Boyne' by 68% and in `Regency' by 189%, primarily through increases in fruit number per cane. Leaf area of the staked canes was 41% larger for `Boyne' and 159% for `Regency' than that of the control canes, suggesting that more leaf area was retained for photosynthesis, resulting in greater yield. Primocane diameter in `Boyne' and primocane height in `Regency' were also increased by staking, but floricane structure was unaffected.

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Chad Finn, Kirsten Wennstrom, Janessa Link, and Jill Ridout

Sixteen western black raspberry (Rubus leucodermis Douglas ex Torrey & A. Gray) populations, collected from through out the Pacific Northwest, and `Munger', the most widely grown black raspberry (R. occidentalis L.) cultivar, were established in 1994 in a replicated trial in Corvallis, Ore. In 1996 and 1997 the seedlings were evaluated for date of budbreak, flowering date, ripening date, fruit size, and disease tolerance. Fruit within a replication were pooled for evaluation of pH, soluble solids, titratable acidity, and anthocyanin content. The plants were vigorous and had produced solid hedges by the time evaluation commenced. The populations were significantly different within each year for all traits except for anthocyanin content in 1996. Rubusleucodermis populations were identified that broke bud and ripened fruit earlier or later than `Munger'; however, all flowered with or sooner than `Munger'. Despite the fact that R. occidentalis is native to eastern North America and R. leucodermis to the West, `Munger' was much less affected by foliar and cane diseases than the R. leucodermis populations. Several populations were as vigorous as `Munger'. `Munger' had fruit that were 30% larger than the mean for any R. leucodermis population. Generally, R. leucodermis had higher pH and lower titratable acidity than `Munger', but many populations had similar soluble solids; lower acidity may partly explain the blandness of R. leucodermis fruit compared with `Munger'. Despite the lighter appearance of R. leucodermis, the anthocyanin levels of some populations were higher than `Munger'. Rubusleucodermis may be a source of earlier fruiting, later budbreak, and vigor when used in breeding but careful selection for fruit size (for the fresh market), acidity (for the processing market), and disease resistance must be done. Rubus leucodermis may also be an excellent source of raspberry bushy dwarf virus (RBDV) resistance in black and red raspberry breeding programs.

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John R. Clark and James N. Moore

‘Natchez’ is the twelfth release in a series of erect-growing, high-quality, productive, floricane-fruiting blackberry ( Rubus L. subgenus Rubus Watson) cultivars developed by the University of Arkansas. ‘Natchez’ ripens early, slightly before