( Lyrene, 2011 ). In our previous study, we have succeeded to obtain several tetraploid shashanbo plants by colchicine treatment (H. Tsuda, unpublished data). The objectives of the present study were as follows: 1) to produce intersectional hybrids from the
Hirotoshi Tsuda, Hisato Kunitake, Mai Yamasaki, Haruki Komatsu, and Katsunori Yoshioka
Hirotoshi Tsuda, Hisato Kunitake, Yo Aoki, Akiko Oyama, Takuya Tetsumura, Haruki Komatsu, and Katsunori Yoshioka
to the section Cyanococcus ( Karizumi, 1979 ; Kunitake et al., 2006 ; Luby et al., 1991 ). Therefore, we produced intersectional hybrids between colchicine-induced tetraploid shashanbo and the tetraploid highbush blueberry ‘Spartan’ ( V
Mark K. Ehlenfeldt, James J. Polashock, Lisa J. Rowland, Elizabeth Ogden, and James L. Luteyn
macrocarpon (Ehlenfeldt et al., in preparation). Several salient points can be made regarding the crosses reported here: Despite being intersectional crosses, it was possible to generate hybrids with 4 x V. meridionale with relative ease, and hybrids
Mark K. Ehlenfeldt and James L. Luteyn
three salient points to be made about these hybrids: 1) Despite being intersectional crosses, it was possible to generate hybrids of V. corymbosum with V. meridionale , using V. corymbosum as females. These hybrids were relatively easy to make and
Paul M. Lyrene
). Most hybrids between diploid and tetraploid Vaccinium species are tetraploid, due to the production of functioning 2 n gametes by the diploid ( Galletta, 1975 ). With so many species and sections, the number of potential intersectional cross
Mark K. Ehlenfeldt and James J. Polashock
Darrow and Camp (1945) who reported the cross V. australe (= V. corymbosum ) × V. arctostaphylos . They did not however subsequently report that any hybrids or advanced selections resulted. Ballington (2000) reported several intersectional crosses
Jon T. Lindstrom, Gregory T. Bujarski, and Brent M. Burkett
Buddleja indica Lam. is encountered frequently as a houseplant or a conservatory specimen and is attractive ornamentally for its oak-shaped foliage. Buddleja indica, a tetraploid African species, 2n = 76, was crossed to the Asiatic tetraploid species B. davidii Franch. The F1 generation was intermediate in foliage character between the two parents. Flowers of the F1 were either white or light lavender in color and the number of flowers per inflorescence was intermediate between the parents. The F1 plants were fertile. These hybrids might be suitable for greenhouse or container culture due to their attractive foliage and floral display.
Barbara Gilmore, Nahla Bassil, April Nyberg, Brian Knaus, Don Smith, Danny L. Barney, and Kim Hummer
types. Intersectional hybrids are crosses between the two groups. Intersectionals (Itohs) have a similar growth pattern to herbaceous peonies, so they are able to withstand temperatures that would kill tree peonies, but their foliage and the flowers have
Diploid plants in Vaccinium section Cyanococcus, including plants of V. darrowi Camp, V. atrococcum. Heller (diploid V. corymbosum L.), a V. atrococcum × V. darrowi F1 hybrid, and a V. atrococcum × V. elliottii Chapmn. F1 hybrid, were hand pollinated in a greenhouse with pollen from diploid V. arboreum Marsh. (Section Batodendron). The resulting seeds were germinated and the seedlings were transplanted to a high-density field nursery. Forty of these F1 intersectional hybrids were selected after 2 1/2 years and transplanted to a 1.5 × 4-m spacing. Most of these plants were vigorous and flowered heavily in subsequent years, but only a small percentage of the flowers produced fruit. In 1990, however, >4000 berries were harvested from the 35 surviving plants. Open-pollinated seed from a much smaller number of berries was planted in Dec. 1987; these seeds produced ≈200 seedlings, some of which had moderate to high fruit set in a field nursery in 1989. Six of these seedlings, which were selected for high vigor, high fruit set, and characteristics intermediate between section Cyanococcus and section Batodendron, had fruit set ranging from 19.4% to 92.7% when pollinated with pollen from tetraploid V. corymbosum cultivars. One of the six seedlings was highly self-fruitful, and some intercrosses among the six seedlings produced much viable seed. Large-scale introgression of V. arboreum genes into tetraploid highbush cultivars likely will be possible by the methods used in this study.
Sylvia J. Brooks and Paul M. Lyrene
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.