Search Results
Abstract
The comparative self-compatibility, intra-, and interspecific crossability of representative clones of V. atrococcum (Gray) Heller, V. caesariense Mackenzie, V. darrowi Camp, and V. tenellum Aiton was determined. The number of germinated seeds and number of vigorous seedlings proved to be the best criteria for evaluation of crossability. The 4 species were largely self-incompatible. Generally, intraspecific and interspecific crossability levels were singificantly higher than those of the self-pollinations. Interspecific crossability was significantly lower than intraspecific crossability. Crossability levels within species and the range in crossability in individual combinations among species were extremely variable. Although F1 hybrids were produced in each of the 6 species hybridizations attempted, the rate of success was highly variable, and the direction in which the cross was made was usually critical. Specific combining ability was considerably more important than general combining ability in achieving species hybridizations. The hypothesis of complete homoploid interfertility in Vaccinium was not valid for these 4 species. The ranking of species crossability (number of vigorous seedlings per 100 pollinations) from highest to lowest was: V. atrococcum – V. caesariense, V. atrococcum – V. darrowi, V. darrowi – V. tenellum, V. caesariense – V. tenellum, V. caesariense – V. darrowi, and V. atrococcum – V. tenellum.
Abstract
Pollen morphology of 10 Vaccinium species, 10 interspecific hybrids, and 3 colchicine-induced polyploids were studied using scanning electron microscopy. Size, exine patterning, furrow and pore size and shape, and general appearance were investigated. Although differing morphological features were generally lacking, some interspecific differences and variation within hybrid populations were noted. Furrow and pore sizes, and the associating opericuli were the most valuable characters. Some species had large furrows with large rounded pores and others had small furrows with insignificant pores. Exine patterning was minimal and, when present, generally occurred in the inter-colporate regions. F1 populations of V. corymbosum × V. elliottii had the greatest exine variation and the degree of exine patterning revealed a possible dosage effect. Exine patterns suggest that the ancestors of V. myrsinites may be V. darrowi and V. elliottii rather than V. darrowi and V. tenellum as previously proposed by Camp.
Abstract
Three pentaploids produced from hybridizing hexaploid Vaccinium ashei Reade and diploid V. darrowi Camp were analyzed for fruit set, number of seeds/fruit, seedlings/pollination, pollen grains/sporad, 2n gamete production, pollen germination, leaf area and berry weight, color, scar, and firmness. The pentaploids were intermediate between the parental species in fruit size and leaf area. There was high variation in fertility and in fruit quality among the pentaploid hybrids.
Interspecific blueberry (Vaccinium spp.) progenies were examined to determine combining abilities and genetic variability for seedling root system size and shoot vigor and to establish whether a large root system is correlated with good growth when plants are grown on a mineral soil and exposed to a moderate soil water deficit. General combining ability (GCA) variance components for root system size and shoot vigor and specific combining ability variance components for shoot vigor were significant. US226, a tetraploid hybrid of V. myrtilloides Michaux × V. atrococcum Heller, had the highest GCA effect for root system size and the lowest GCA effect for shoot vigor. US75 (V. darrowi Camp × V. corymbosum L.) had the highest GCA effect for shoot vigor and was second in GCA effect for root system size. Comparison of the crosses containing G111 (V. corymbosum) with those containing G362 (V. corymbosum) indicates that selecting for the best V. corymbosum clone to start a breeding program seems as important as selecting the mineral soil-adapted parent. Root system ratings were highly correlated with total dry weight of field-grown plants (r = 0.89). The method used in this study to evaluate seedlings for root system size and shoot vigor could be used to eliminate the less vigorous plants from a population before field planting and to evaluate mineral soil adaptability.
Fertility of F1 hybrids and their open-pollinated progeny was studied for the intersectional cross Vaccinium darrowi Camp × V. arboreum Marsh as part of a project to determine the feasibility of using V. arboreum to breed vigorous, drought-tolerant southern highbush blueberry cultivars. The 16 F1 hybrids that were studied were vigorous but very low in fertility. Second generation hybrids [MIKs (mother is known) obtained by open-pollination of the F1s] and MIK derivatives were extremely variable in vigor and fertility, but averaged far higher in fertility than the F1s as evidenced by pollen stainability and amount of pollen produced. F1s produced an average of 0.4 seedlings per 100 pollinated flowers when hand-pollinated in a greenhouse with pollen from V. darrowi, 0.2 when pollinated by V. arboreum and 3.4 when pollinated by cultivated highbush. Some MIKs that were crossed with other MIKs and with cultivated southern highbush were very high in male and female fertility. Female fertility was estimated in greenhouse crosses from fruit set, berry weight, number and weight of seeds, number of plump seeds per berry, and number of seedlings obtained. Male fertility was estimated by pollen stainability with acetocarmine and amount of pollen shed. Chromosome counts showed that three F1s were diploid and that four fertile MIKs were tetraploid. One MIK appeared to be aneuploid. Aneuploidy may explain much of the low fertility found in MIK populations. These results indicate that good progress is being made in returning the hybrid plants to cultivar quality in only a few generations of backcrossing.
Abstract
Vaccinium species collected from the eastern United States were grown and fruited at Castle Hayne, N.C. Harvest season extended from 5 June to 22 Aug. Vaccinium angustifolium Ait. was earliest ripening. Vaccinium myrtilloides Michx., V. elliotti Chap., diploid V. corymbosum L., and tetraploid V. pallidum Ait. populations also contained very early- to early-ripening seedlings. Early-ripening seedlings were not observed in tetraploid V. corymbosum populations and reached peak ripeness around mid-June, about with ‘Bluecrop’. One tetraploid V. corymbosum population continued ripening into early August. Vaccinium ashei Reade populations from Georgia began ripening about 2 weeks earlier than Florida V. ashei or Arkansas V. amoenum Ait. populations. One Georgia V. ashei population was only slightly later than tetraploid V. corymbosum. The Florida V. ashei populations continued ripening into late August. The diploid species V. darrowi Camp, V. tenellum Ait., and V. stamineum L., were all basically late in ripening. The potential utility of these species in breeding for both early- and late-ripening Vaccinium genotypes is discussed.
Abstract
Bulk A horizon samples of 4 soils, with or without the addition of peatmoss, and 5 blueberry crosses were used in a study of the adaptability of blueberries to upland soil conditions under 3 fertilization regimes and trickle irrigation in outdoor pots. Blueberry progenies ranged from essentially pure highbush (Vaccinium corymbosum L.) to interspecific hybrids containing varying amounts of evergreen (V. darrowi Camp), lowbush (V. augustifolium Aiton), black highbush (V. atrococcum Heller), and rabbiteye (V. ashei Reade) blueberry germplasm. Blueberry growth, as measured by plant volume, initially was greatest on Manor clay loam, a Piedmont soil high in clay (30%), but by the 2nd growing season, growth was superior on Berryland soil. Various fertilizer sources affected small differences in growth. Generally those progenies that contained less highbush (V. corymbosum) parentage produced more vigorous growth. Depth of rooting and estimated root distribution were affected significantly by soil, but the addition of peatmoss had no consistent effect. Berryland sand and Manor loam soils, which represent extremes in clay content, both produced the deepest root systems. Fruiting and fruit characteristic data from the 2nd growing season indicated a significant effect of peatmoss on the Pope and Galestown soils, which resulted in lowered total fruit acidity. The Berryland soil produced fruit with the lowest total acidity. Blueberry plant growth over the first 2 seasons indicates that soil type can have pronounced effects on plant growth and rooting. These growth differences were due to soil characteristics other than particle size distribution, with fertilizer source having minimal effects on growth.
Abstract
A range of soils, with or without the addition of peatmoss, and seedlings of blueberry progenies were used in an outdoor pot study to examine the adaptability of blueberries to upland soil conditions with controlled fertilizer additions and trickle irrigation. Blueberry progenies ranged from essentially pure highbush (Vaccinium corymbosum L.) to interspecific hybrids containing varying amounts of evergreen (V. darrowi Camp), lowbush (V. angustifolium Aiton), black highbush (V. atrococcum Heller), and rabbiteye (V. ashei Reade) blueberry germplasm. The soils represented the 3 physiographic regions of the eastern United States with Berryland sand used as a comparative control. Leaf analysis for N, P, K, Ca, and Mg showed significant effects of soil, but no consistent effect of peatmoss addition or fertilizer source in the 2 years of the experiment. There were significant differences among progenies. Foliar Fe, B, Al, Zn, and Cu concentrations varied independent of soil material, progeny, or fertilizer source. Leaf Mn was significantly increased from solid 10N-4P-8K fertilizer and a significant soil by progeny interaction existed. Those progenies containing some V. angustifolium tended to have increased foliar Mn levels. The reduced vigor of the blueberry progenies grown on soils other than the Berryland sand was tentatively ascribed to induced nutrient imbalances, involving Ca, Fe, and Mn, possibly being governed by soil cation exchange capacity and organic matter reactivity.
Abstract
To determine if the net CO2 assimilation and water use efficiency (WUE) of highbush blueberry under high temperature can be improved genetically, gas exchange determinations were made for a selection of Vaccinium darrowi Camp (Florida 4B), a highbush cultivar (Bluecrop) (V. corymbosum L.), their F1 hybrid (US75), and two crosses of the F1 hybrid to another improved genotype (US239 and US245). All genotypes responded parabolically to increasing temperature at vapor pressure deficits <1 kPa. Maximum CO2 assimilation of US75 (15 µmol·s–1·m–2) was 30% to 40% higher than either parent. Carbon dioxide assimilation of US75 and Florida 4B was optimum at 30°C and that of ‘Bluecrop’ at 20°. The optimum for US239 was similar to ‘Bluecrop’, and that of US245 to Florida 4B. Florida 4B had higher WUEs than ‘Bluecrop’ at both 20° (5.64 µmol CO2/mmol H2O to 4.01) and 30° (3.73 to 2.53). US239 and US245 had significantly (P < 0.05) higher WUEs at 30° than did ‘Bluecrop’. Residual conductance to CO2 (gr) decreased in ‘Bluecrop’ when temperature was raised from 20° to 30°, but increased in all other genotypes. Due to the favorable gas exchange properties of US75 and US245 at 30°, we suggest that the high temperature tolerance of V. darrowi may be heritable and that US245 may be used to improve the heat tolerance of highbush blueberry.
there may have been a contaminant present. The molecular ion and fragments for Compound 7 matched those reported in the literature for 5-O-caffeoylquinic acid, an isomer of chlorogenic acid previously identified in foliage from the wild blueberry, V