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- Author or Editor: Arlen D. Draper x
- Journal of the American Society for Horticultural Science x
Abstract
Open-pollinated species, interspecific hybrid seedling populations, and selected clones propagated by softwood cuttings and tissue culture were used to further evaluate the use of dry soil to screen blueberry seedlings for drought resistance. These different propagation types of Vaccinium (subgenus Cyanococcus) were screened for drought resistance in a Galestown fine sandy loam soil. The soil was permitted to dry to progressively higher soil tension levels to a maximum of 0.8 MPa. The plants were evaluated by scoring them on a 1 to 9 shoot damage rating scale and by determining the fraction of total biomass partitioned as roots. Drought resistance in blueberries is heritable and there is a high degree of genetic diversity within and among Vaccinium spp. for resistance to water deficits. Southern species (Vaccinium darrowi Camp, V. elliottii Chapman, and V. ashei Reade) were more drought-resistant than northern species (V. corymbosum L., V. vacillans Torrey, and V. myrtilloides Michaux), which demonstrated the reliability of this soil screening method. Clones with half their germplasm from southern species were usually drought-resistant. This screening method can be used to select for shoot and root vigor and drought resistance in 6- to 7-month-old blueberry seedlings.
Abstract
Five blueberry interspecific hybrids (3 tetraploids, 1 pentaploid, and 1 hexaploid) and 2 highbush (Vaccinium corymbosum L., 2n = 4x = 48) blueberry clones were crossed in all combinations. Seeds per pollination and seed germination were the criteria used to measure the success of these crosses. The tetraploid interspecific hybrids were fully cross-fertile with the highbush clones and with each other. The pentaploid and hexaploid interspecific hybrids were only partially cross-fertile with the highbush clones and with the tetraploid interspecific hybrids; nonetheless, they still produced an adequate amount of viable seed in most combinations. Significant reciprocal differences in crossability were detected for 4 of the 5 species hybrids.
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.
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.