access by small-landholder farmers. Cultivar MT 56 could be profitable for farmers if its seed is available. Because small-landholder farmers lack access to open-pollinated cultivars that are disease tolerant and an improved seed distribution system in
Sharon M. Tusiime, Gail R. Nonnecke, Dorothy M. Masinde, and Helen H. Jensen
Jonathan D. Mahoney, Thao M. Hau, Bryan A. Connolly, and Mark H. Brand
a randomized field planting consisting of 120 Aronia accessions (with three replicates) and representing all four species and various ploidy levels. Intra-accession progeny variability was evaluated by growing out seedlings from their open-pollinated
Phillip A. Wadl, Timothy A. Rinehart, Adam J. Dattilo, Mark Pistrang, Lisa M. Vito, Ryan Milstead, and Robert N. Trigiano
al. (2011) and maintained in vitro and in vivo. Open-pollinated seeds (achenes) were collected from plants growing at the University of Tennessee and the Hiwassee and Ocoee Rivers and dried in paper bags at ambient temperature in the laboratory for 3
Melvin R. Hall and Mark K. Ehlenfeldt
A rabbiteye blueberry selection, T-285, appears parthenocarpic when grown in the greenhouse and sparsely seeded when grown in the field. This semi-seedless character was analyzed to determine the nature and degree of its cross- and self-fertility in comparison to its parents, `Tifblue' and `Delite'. Ovule numbers from T-286 were similar to those of `Tifblue', but lower than those of `Delite'. Seed numbers of open-pollinated `Tifblue' and T-286 were similar, and lower than `Delite', but T-286 was notable in having fruit 60% larger than `Tifblue' and 10% larger than `Delite'. Both `Tifblue' and T-286 had a tendency to produce some open-pollinated fruit with few or no seed present. None of the selections produced significant amounts of fruit when self-pollinated. When cross-pollinated, all selections set more seed, but this was less pronounced with T-286 than with either of its parents.
Marietta Loehrlein and Dennis T. Ray
Triploid watermelon seed are produced by crosses between tetraploid female and diploid male plants. When open-pollinated, the resultant seed can be either tetraploid due to self-pollination or triploid from pollination by a diploid. This work was done to test if triploid and tetraploid seed can be separated on the basis of seed thickness and weight. Open-pollinated seed from a 4n × 2n cross were separated by either thickness (grouped into 0.1-mm increments) or weight (5-mg increments). Seed were germinated in a greenhouse and transplanted into the field. Plants were scored as either triploid or tetraploid by use of a genetic marker system. When separated by either thickness or weight, triploid and tetraploid seed were found in essentially each size category. There were no significant differences between populations for thickness, and the mean weights were essentially equal between triploid and tetraploid seed.
Sylvia J. Brooks and Paul M. Lyrene
The extent of self-fertility and self-fruitfulness was studied in Vaccinium arboreum Marsh, V. darrowi Camp, and in seedlings, termed MIKs, from open-pollination of V. darrowi (section Cyanococcus) × V. arboreum (section Batodendron) F1 hybrids. The open pollinations that produced the MIKs occurred in a field containing tetraploid southern highbush selections (based largely on V. corymbosum L.), and the pollen parents of the MIKs are believed to be southern highbush selections. The MIKs that were studied had been selected for high fruit set after open pollination in the field. Both V. arboreum and V. darrowi exhibited very low self-fruitfulness and self-fertility when hand-pollinated in a greenhouse; the former produced no seedlings from more than 600 selfed flowers, and the latter produced only 13. By contrast, southern highbush clones averaged 70 seedlings per 100 pollinated flowers when selfed and 230 when crossed. Self-fertility and self-fruitfulness of the MIKs were higher than those of V. arboreum and V. darrowi but lower than those of southern highbush selections. MIK × MIK crosses gave fewer seedlings per 100 pollinated flowers (84) than highbush × highbush crosses (230), probably reflecting their hybrid ancestry. Although introduction of V. arboreum genes into southern highbush blueberry gives plants of excellent vigor and adaptation to north Florida, several generations of breeding will be needed to obtain cultivars with high fertility and berry quality.
The seed producing system in viola (Viola ×cornuta) was investigated to improve seed yield and to save labor. In a flower five anthers sequentially dehisced; pollen grains were continuously supplied to the anterior petal, which played a significant role in pollination, throughout the flowering period. Evidence from pollen and ovule number suggests that the species is facultative autogamy. Each flower opened more than 10 days was independent of the success in fertilization and kept seed producing ability during the flower longevity period. Pollen grains also maintained viability during the flower longevity period. Pollinators were indispensable for pollination of viola, but pollination in viola was done by a different mechanism from the typical insect-mediated pollination that sticky pollen grains adhere to the exposed stigmas. Pollen grains, accumulated around the entrance of the stigmatic cavity, entered into the cavity by the movement of pollinators. Although the visitation of pollinators was occasional, solitary bees primarily contributed to the pollination of viola. On the other hand, germination of pollen grains on the stigmatic surface was under 50%. Seed set was much lower than the germination percentage of pollen grains. A viola flower had the ability for additional pollinations and fertilization for some days after the fertilization success in some ovules in the flower. This characteristic suggested that repeated pollination is effective to increase the number of mature seeds in a capsule.
Greg T. Browne, Joseph A. Grant, Leigh S. Schmidt, Charles A. Leslie, and Gale H. McGranahan
objective of this study was to examine diverse open-pollinated seed families of P. stenoptera for: 1) relative resistance to P. cinnamomi and P. citricola; and 2) graft compatibility with key current cultivars of Persian walnut. It was hypothesized
J.R. Schupp, S.I. Koller, and W.D. Hosmer
This study was undertaken to test the efficacy of a power duster for supplemental pollination of `McIntosh' apple trees, where lack of nearby pollinizing cultivars was thought to be a limiting factor to productivity. The pollen duster was ineffective in increasing fruit set, fruit size, or seed number in fruits on limbs that were covered with spun-bonded rowcover material prior to bloom. Applying supplemental pollen to open-pollinated `McIntosh' trees had no effect on fruit set, yield, fruit size, or seed number, regardless of pollen dose, timing, or number of applications. Dispersal of supplemental pollen with a power duster appears to be an inefficient method of pollinating apple trees.
Kenna E. MacKenzie
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.