inheritance of this trait and an evaluation of its potential for development. Materials and Methods A parthenocarpic variant, G-176, was discovered in highbush blueberry ( Vaccinium corymbosum L.) (2n = 4x = 48) in a family of the pedigree G-105 × E-204
Abstract
Percent fruit set, fruit size, total seeds/berry, developed seeds/berry, percent developed seeds/berry, and percent pollen stainability were examined in 4x × 5x and 5x × 4x progenies derived from Vaccinium ashei Reade/V. corymbosum L. pentaploid hybrids backcrossed to V. corymbosum. All fertility parameters indicated that the BC1 progenies were more fertile than the pentaploid hybrids. Pollen stainability indicated that the BC1 derivatives were less fertile than the parental species. All fertility parameters were significantly and negatively correlated with chromosome number, which ranged from the tetraploid (2n = 4x = 48) to pentaploid (2n = 5x = 60) levels within these progenies.
Blueberries ( Vaccinium corymbosum L.) are becoming important commercial crops because of their healthy and flavorful properties, and they can be propagated by seeds, grafting, tissue culture, and hardwood/green cuttings ( Fischer et al., 2012
A tetraploid blueberry population resulting from a cross of US 75 {a tetraploid hybrid of Fla 4B [a selection of Vaccinium darrowi Camp (2n = 2x = 24) × `Bluecrop' [(V. corymbosum L. (2n = 4x = 48)]} × `Bluetta' (4x) was used to generate a genetic linkage map of US 75 by randomly amplified polymorphic DNA (RAPD) analysis. One hundred and forty markers unique for Fla 4B that segregated 1:1 in the population were mapped into 29 linkage groups that cover a total genetic distance of 1288.2 cM, with a range of 1.6 to 33.9 cM between adjacent markers. The map is essentially of V. darrowi because US 75 was produced via a 2n gamete from Fla 4B and only unique markers for Fla 4B were used. Therefore, all the chromosomes of V. darrowi could be represented in the map.
. corymbosum ) and pollinator visitation levels reveal some unpollinated Vaccinium can initially set green fruit, but they ultimately abort berries before ripening. Cultivated rabbiteye blueberries and southern highbush blueberries produced the most
citric acid and titratable acidity. In blueberries, malic acid is the predominant organic acid in rabbiteye ( Vaccinium virgatum ) cultivars, whereas citric acid is the predominant in V. corymbosum , and Vaccinium myrtillus . Quinic and Shikimic acids
Abstract
Five-year-old ‘Collins’ highbush blueberries were treated in August with glyphosate (N-phosphonomethyl glycine) at 0.36, 3.6 and 7.2 g/liter acid equivalent as a spot treatment alone or with pruning or applying paraquat (1, 1-dimethyl-4,4′-bipyridinium ion) at 1.2 g/liter to remove green tissue prior to glyphosate application. Initial response was terminal dieback of young canes. Symptoms the following spring included additional terminal dieback, leaf and cane morphological aberrations, and elongation of the flower corolla. One year after treatment, regrowth was normal. There was no effect on blueberry yield the season following treatment.
The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.
Abstract
Seed counts from self- and cross-pollinated highbush blueberry cultivars suggested that fertility in both mating systems is under similar genetic control. Viable seed set following selfing and outcrossing was inversely correlated with zygotic levels of inbreeding, and percentage of seed abortion in both crosses showed a positive association with zygotic F values. Among six genotypes, cross- and self-fertility were highly correlated. Fluorescent microscopy revealed no differences in the frequency of self and foreign pollen tube growth into ovules. Variation in self- and cross-fertility among these cultivars was attributed to differences in zygotic levels of homozygosity and cumulative expression of recessive mutations that promote seed abortion.
Abstract
Field applications of N greater than 34 kg/ha to highbush blueberry plants on an Atsion sand did not result in increased fruit production. Application of more than 64 kg N/ha may be detrimental to blueberry production. The optimum N content in the median leaves sampled one month after harvest of lateral shoots averaged 1.65% N over a 5 year period. A biennial bearing pattern occurred consistently at each of N fertilizer levels. Leaf N levels tended to be lower during years of high production than during years of low fruit production. Ca levels in leaf tissue were found to be below the sufficiency level during low production years when leaf N was high and above the sufficiency level in high production years when leaf N was lower.