Abstract
Sugar concentration in nectar from ‘Jersey’ variety blueberry blossoms was significantly higher than that from ‘Rubel’. Nectar volume was not significantly different for the 2 varieties. For both varieties sugar concentration increased as the day progressed and volume of nectar decreased. As the blossoms aged, nectar concentration and volume increased for both varieties. Paper chromatographic analysis of nectar from both varieties indicated no differences in component sugars.
Experiments were conducted with V. darrowi and two cultivars of southern highbush blueberry, `Sharpblue' and `Misty,' to test whether V. darrowi and cultivars derived from it are photoperiodic with respect to flower bud initiation. Plants of each cultivar were grown under three different photoperiod treatments [long days (LD) = 16-hour photoperiod; short days (SD) = 8-hour photoperiod; and short days + night interrupt (SD-NI) = 8-hour photoperiod with 1-hour night interrupt] at constant 21 °C for 8 weeks. Vegetative growth was greatest in the LD plants of both cultivars. Flower bud initiation occurred only in the SD treatments, and the lack of flower bud initiation in the SD-NI treatment indicates that flower bud initiation is a phytochrome mediated response in Vaccinium. Previously initiated flower buds on the V. darrowi plants developed and bloomed during the LD treatment, but bloom did not occur in the SD and SD-NI treatment plants until after those plants were moved to LD. These data indicate that flower bud initiation in both V. darrowi and southern highbush blueberry is photoperiodically sensitive, and is promoted by short days, while flower bud development is enhanced under long days.
Blueberry cultivars were treated with either soil drenches or foliar applications of paclobutrazol. Soil drenches of 25 mg·L-1 inhibited shoot elongation and stimulated earlier and greater flower bud production on `Bluetta', `Bluecrop', and `Jersey'. The treatments increased bud numbers 359% to 797%, and stimulated compound bud formation, while reducing formation of vegetative buds. This resulted in overcropping and reduced fruit size. Foliar applications at concentrations of 5, 10, 50, and 100 mg·L-1 increased bud set. Treatments did not significantly alter time to 50% flowering in `Bluecrop' or `Duke', but hastened flowering up to 5 days in `Blueray' at 200 ppm. Fruit ripening was significantly delayed at 100 and 200 ppm in `Bluecrop' due to overcropping, but no delays were observed in `Blueray' or `Duke'. Plant size and vigor appeared to be a determining factor in plant response. Chemical name used: PP333 or (2RS,3RS)-l(4-chlorophenyl)-4,4-dimethyl-2-(l,2,4-triazol-1-yl)pentan-3-ol (paclobutrazol).
Calcium sprays were applied to `Bluecrop' highbush blueberry bushes between petal fall and fruit harvest. In 1992, bushes received five sprays between 18 June and 16 July that totaled 0, 1.0, 1.9 or 3.8 kg Ca/ha. Calcium was applied as CaCl2 at spray concentrations of 0.08% to 0.2% Ca. Treatments in 1993 consisted of a control; 12.1 and 24.2 kg Ca/ha as CaCl2; and 12.1 kg Ca/ha as the commercial product Nutrical. Calcium was applied in seven sprays between 4 June and 16 July using spray concentrations of 0.1% to 0.4% Ca. Berry samples were hand-picked, stored for 3 to 20 days, and evaluated. Treatments had no effect on the percentage of soft or rotten berries, berry firmness, or berry Ca concentrations during either year. Calcium applications increased leaf Ca concentrations. Chemical names used: calcium trihydroxyglutarate (Nutrical).
This study was conducted in the greenhouse by running two experiments at different temperature regimes (22°C day and 13°C night and 33°C day and 22°C night). One-year-old tissue culture propagated plants were irrigated at three different soil moisture tension levels (5, 15, and 30 cnbars) and either exposed to moving or still air. The moving air treatment was created by two 51-cm-diameter fans running at either low (5.6 mph) or medium (8.2 mph) speed. Each experiment included, forty-eight plants arranged in a randomized complete block design. Each block consisted of a greenhouse bench containing two fans, a plastic dividing wall and two plant replications for each treatment. Canopy volume measurements were taken at the beginning, middle and end of each experiment to estimate growth rate. At the end of each experiment, total leaf area and leaf, stem and root dry weight data were collected. In the moderate temperature experiment, the still air treated plants had the highest canopy volume and leaf weight ratio while the moving air treated plants had the highest stem weight ratio. The only difference for the moisture treatments was the 5-cnbar treatment had the highest canopy volume. In the high temperature experiment, the still air treated plants had the highest canopy volume, total leaf area, leaf dry weight, shoot/root ratio, leaf weight ratio and leaf area duration while the moving air treated plants had the highest root weight ratio. The 5-cnbar treatment had the highest canopy volume and biomass accumulations. The 30-cnbar treatment had the highest root weight ratio.
Abstract
The 3-monoarabinosides and 3-monogalactosides of delphinidin (Dp), petunidin (Pt), malvidin (Mv), and peonidin (Pn) as well as small amounts of the 3-monoglucosides of Dp, Pt, Mv, Pn, and cyanidin (Cy) were isolated from ripe blueberry fruit, variety ‘Croatan’. Small amounts of the 3-monogalactoside of Cy were present also. None of these 14 anthocyanins (Acy) were acylated. The major Acy were (in descending order): Mv-3-galactose, Dp-3-galactose, Dp-3-arabinose, Pt-3-galactose, Pt-3-arabinose and Mv-3-arabinose.
Abstract
Experiments utilizing both natural and artificial chilling conditions were conducted to evaluate chilling models for estimating rest completion of highbush blueberries. Temperatures of 1° and 12°C were effective in satisfying the rest requirement of blueberries, but were less effective than 6°. Thus, neither the Utah chill unit model nor the accumulated hours below 7.2° model are accurate, since the Utah model does not consider temperatures below 1.4°C as effective in chilling and the accumulated hours below 7.2° model does not consider temperatures above 7.2° as effective. A modification of the Utah model allowing each hour at 1° to contribute 0.5 chill units gave predictable results for highbush blueberries. Natural field chilling was more effective in satisfying rest requirements than artificial chilling in cold chambers.
Abstract
V. corymbosum L./V. ashei Reade pentaploid blueberry hybrids backcrossed to tetraploid V. corymbosum yield tetraploids and aneuploids. Six BC1 derivatives, a tetraploid (2n = 4x = 48) and five multiple aneuploids (2n = 4x + 3, 4, 5, 8, and 9 = 51, 52, 53, 56, and 57) were selfed, intercrossed, and backcrossed to the V. corymbosum cv. Bluecrop. The fertility parameters measured were percent fruit set (FS), total seeds/berry (TS), developed seeds/berry (DS), percent developed seeds/berry (PDS), percent seed germination (PG), and number of seedlings (NS). Values of all parameters decreased as aneuploidy level of the cross (sum of extra chromosomes, number of chromosomes over 2n = 48, in the seed and pollen parent) increased; the relationship was principally linear. A significant quadratic relationship was noted for PDS. Diallel analysis revealed that reciprocal effects were significant for all parameters except PG and were the second most important factor contributing to variability among crosses for NS. All parameters indicated a high level of self sterility. Although the aneuploids in this study had reduced crossability, they can produce sizable progenies with practical efficiency. Contrary to previous reports, these results suggest that pentaploid hybrids and their BC1 derivatives can be used to facilitate gene transfer from V. ashei into V. corymbosum.
Abstract
Pollination of about 7000 flowers of tetraploid highbush blueberry clones with pollen from a wild diploid species, V. elliottii (Chapm.) Small, gave 25 phenotypically obvious hybrids. Examination of 18 of these hybrids showed that they included triploids, tetraploids, pentaploids, and aneuploids. Some hybrids appeared to be mosaics, as evidenced by chromosome-number variability in premeiotic flower buds. Most hybrids were highly vigorous. The triploids were completely female sterile and the pentaploids ranged from partially to completely female sterile when open-pollinated. Three of the tetraploids examined were highly fertile and extremely vigorous. The occurrence of 3x-4x mosaicism suggests that the 3x hybrids may have arisen from chromosome loss in 4x plants rather than from 3x zygotes. Morphological similarities between certain of the 5x hybrids and the west Florida race of the native allohexaploid species V. ashei Reade suggest V. corymbosum L.–V. elliottii allohexaploidy as one possible mode of origin for V. ashei.
Abstract
Anthocyanins (Acy) in ripening blueberry fruit of the cv. Wolcott were identified and their amounts estimated spectrophotometrically. Fifteen Acy, all combinations of Mv, Pt, Pn, Dp, and Cy with glu, gal, or arab4 in the 3-position were found in unripe, red fruit. Ripe and overripe fruit contained all these Acy except Pn-gal. Cy-glu and Cy-gal comprised about 40% of the total Acy in unripe fruit, while Mv-glu and Mv-gal constituted about 60% in the overripe fruit. The relative proportions of 3-glucosides, 3-galactosides, and 3-arabinosides remained fairly constant throughout fruit ripening.