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- Author or Editor: P.M. Lyrene x
- HortScience x
Abstract
Seventeen rabbiteye blueberry clones observed for 4 years at Gainesville, Fla., showed much year-to-year and clone-to-clone variation in flowering and ripening dates. If, however, year effects were removed by expressing flowering and ripening dates as deviations from year means, the sequence in which the 17 clones flowered and ripened was highly repeatable, with little clone × year interaction.
Abstract
Fifty-four seedlings of Vactinium ashei Reade, selected for large fruit and high fruit quality from 3000 seedlings of 8 crosses, were scored for dates of 50% anthesis and 50% fruit-ripening in 1981 and 1982. The earliest-ripening selection was 7 days earlier than the earliest cultivar in 1981 and 15 days earlier in 1982. Repeatability (seedling correlation between years, r = .84) was high for ripening date but somewhat lower for flowering date (r = .61) and flowering-to-ripening interval (r = .62). Most of the variation in ripening dates and in the flowering-to-ripening interval was genetic, but variation in flowering dates was due more to year effects than to genetic effects.
Abstract
Eighteen cultivars of the Chinese jujube (Zizyphus jujuba Mill.) grown in Florida comprised 2 flowering types based on the time of day when the flowers open. Flowers on 10 cultivars open each day between 0700 and 1000 hr and on the other 8 between 1400 and 1700 hr. Despite ample opportunity for cross-pollination and intense activity by pollinating insects, some cultivars set little or no fruit. Cultivars that fruit heavily and reliably are parthenocarpic. Supplemental light in the fall prolongs flowering and fruiting and could substantially increase yields.
Abstract
Multiple shoot formation from shoot tips taken from juvenile rabbiteye blueberry (Vaccinium ashei Reade) seedlings was induced on Knops medium with agar, casein hydrolysate, and N6-(∆2-isopenteny1)-adenine (2iP) at 15 mg/liter. These shoots could be easily subcultured and rooted readily when cut off and inserted into a peat-perlite mixture under mist in the greenhouse. Nonjuvenile shoot tips from rabbiteye cultivars were difficult to establish in cultures. Successful establishment of some clones occurred by formation of fine, filamentous shoots which were as amenable to subculture as juvenile shoots. A 50-fold multiplication rate every 4 months was obtained with some clones.
Abstract
Ten colonies of Vaccinium darrowi Camp were sampled at each of 9 sites in the Florida panhandle and 6 sites in and around the Ocala National Forest in the central Florida peninsula. The colonies averaged 53 cm tall in the panhandle, with leaves 9.8 mm long and 4.1 mm wide. By contrast, colonies in the peninsula averaged 136 cm tall—well outside the range described for the species—with leaves 12.7 mm long and 5.7 mm wide. The species was diploid and entirely evergreen in both regions. In the central Florida peninsula, natural hybrids between V. darrowi and a 3-m tall, deciduous, diploid race of highbush blueberry (V. corymbosum L.) are common where streams and lakes border the dry scrub habitat of V. darrowi. The robust form of V. darrowi in the Florida peninsula may have evolved from the petite form in the panhandle as a result of introgression from the highbush coupled with selection for characteristics that enhance survival on the deep, xeric sands of the peninsula. V. darrowi from the central peninsula has characteristics that make it valuable in breeding blueberry cultivars.
Abstract
Removing the terminal 10 cm from shoots of rabbiteye blueberry (Vaccinium ashei Reade) plants on 27 Oct. induced flower buds below the cut, even though no new vegetative growth occurred. The average number of new flower buds formed per twig ranged from 1.3 for ‘Delite’ to 6.1 for ‘Climax’ with an average of 3.0 for the clones tested. Unpruned twigs of the same clones averaged only 0.5 new flower buds on comparable twig sections. Tying unpruned twigs to a horizontal position during the period of flower bud formation had no effect on number or location of flower buds on the twigs.
Abstract
Blueberry is clonally propagated by hardwood and softwood cuttings, and by micropropagation. Zimmerman and Broome (7) reported 22.8 µm 1H-indole-3-acetic acid (IAA) plus 73.8 µm N-(3-methyl-2-butenyl)-1H-purin-6-amine (2ip) to be optimal for axillary shoot proliferation. Lyrene (4) found that 28.5 µm IAA added to medium containing 73.8 µm 2ip had no effect on shoot multiplication. Although lowbush blueberries produced increasingly more shoots as 2ip concentrations increased from 0 to 147.6 µm (2), three highbush clones produced fewer shoots at the 147.6 µm than at lower concentrations (1).
Fruit set, fruit size, and seed production after hand pollination in a greenhouse were compared for southern highbush blueberry managed in two ways: a) 69 clones were allowed to go dormant and lose their leaves in the field before being dug and subjected to 1000 hours at 5 °C and b) 26 clones were kept growing in a greenhouse through fall and winter without leaf loss and without chilling, to induce flowering on plants that had mature leaves. On each plant in both management systems, some flowers were self-pollinated, some were cross-pollinated, and others had the styles removed before anthesis to prevent pollination. For >1000 flowers per pollination treatment on the deciduous plants, fruit set averaged 1% for no pollination, 46% for self-pollination, and 76% for cross-pollination. The corresponding values for the evergreen plants were 23%, 59%, and 81%. Parthenocarpic berries averaged 0.37 g/berry for deciduous plants and 1.01 g for evergreen plants. Both crossed and selfed berry weights averaged slightly higher for the evergreen plants than for the deciduous plants, but seed number per berry was much lower for the evergreen plants (12 seeds in crossed berries and four seeds in selfed berries) compared to deciduous plants (37 and 8). Southern highbush blueberry plants that flower without going dormant appear to have much higher parthenocarpic capabilities than those that flower after a dormant period.
A yellow-leaf seedling marker, r, was used to determine if there was preferential chromosome pairing in a group of tetraploid southern highbush blueberry hybrids. Plants with four copies of r (no copies of R) fail to develop anthocyanins, and cotyledons, hypocotyls, leaves, stems, and other vegetative tissues have a bright yellow-green color. In the hybrids that were studied, two genomes were from the diploid wild species, V. elliottii Chapman, and both carried the recessive marker r. The other two genomes were from southern highbush cultivars and both carried the dominant wildtype allele, R. When RRrr hybrids were intercrossed or crossed to rrrr yellow-leaf plants, the number of yellowleaf rrrr seedlings obtained usually equalled or exceeded the number predicted from nonpreferential chromosome pairing. Since rr gametes can only be produced by RRrr plants when R and r chromosomes pair at Meiosis I, there was no evidence that the chromosomes derived from V. elliottii were pairing at a higher-than-random rate.
Abstract
Eleven cultivars of Vaccinium ashei Reade in a 10-year-old planting were compared for number of flowers per inflorescence and for percentage of the flowers that set fruit on bagged and open-pollinated branches. Mean flower number per cluster ranged from 7.6 for ‘Bluegem’ to 5.3 for Florida-M. Mean percentage of fruit set on open-pollinated branches ranged from 75% for ‘Southland’ to 36% for ‘Tifblue’. On branches bagged to exclude bees, the range was from 21% for ‘Beckyblue’ to 3% for Tifblue.