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and other hybrids. The objective of this report is to summarize the interspecific crosses in the genus Penstemon at the UNL WCREC over 10 years, 1996–2005, and compare those results to other reports in the literature. The majority of species used in

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create a hardy blue water lily hybrid through the infusion of germplasms from tropical water lilies with several colors, including blue, in subgenera Anecphya , Confluentes , and Brachyceras. In most interspecific crosses, however, the existence of

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flush in chance seedlings ( Fiala and Vrugtman, 2008 ). Early advancements in breeding produced vigorous interspecific hybrids including S. × hyacinthiflora from crosses between S. oblata and S. vulgaris by the Lemoine nursery ( Lemoine, 1878

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intraspecific crossing combinations within L. chalcedonica and L. × haageana ; 2) 102 interspecific crossing combinations within Lychnis spp.; and 3) 47 intergeneric crossing combinations between Lychnis spp. and Silene spp. Five crosses including

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. Backcrossing experiments. Plants used in crosses with southern highbush blueberry cultivars (4x) included two V. darrowii × V. corymbosum hybrids from crosses made in 2004, three interspecific hybrids from crosses made in 2005, and 17 interspecific

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interspecific hybrids in the genus. However, with the exception of intentional crosses between culinary sage ( S. officinalis ) and S. lavandulifolia ( Sanchez-Gomez et al., 1995 ), S. fruticosa , and S. tomentosa ( Putievsky et al., 1990 ), all reported

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the number of inflorescences/number of fruit and this was used to determine self-incompatibility. Self-pollinations were conducted in 2006 and 2007 ( Table 1 ) and intra- and interspecific crosses were conducted in 2006 to 2008 ( Table 2 ). Because

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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.

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Cucurbita ecuadorensis is a valuable source of multiple virus resistance. It is resistant to zucchini yellow mosaic virus (ZYMV), papaya ringspot virus (PRSV), watermelon mosaic virus, tobacco ringspot virus, squash mosaic virus, and cucumber mosaic virus (CMV). Its virus resistance can be transferred to squash and pumpkin, but sterility barriers must be overcome. The cross Cucurbita maxima× C. ecuadorensis can readily be made, and there is no need for embryo culture. Pollen fertility of the hybrid is somewhat reduced, but sufficient for producing F2 seed. Segregation for sterility occurs in the F2, but selection can be made for fertile plants that are homozygous for virus resistance. Cucurbita ecuadorensis is much more distantly related to C. pepo than to C. maxima, and there are more formidable barriers in this interspecific cross. The cross is very difficult to make with some C. pepo cultivars, but other cultivars are more compatible. Viable seed were not produced, but hybrid plants were obtained by embryo culture. Although both parents were monoecious, the hybrid was gynoecious. Male flower formation was induced by treating the hybrid with Ag or GA, but they were male-sterile. F2 seed was not obtained, but backcross seed was easily produced by using the interspecific hybrid as the maternal parent in crosses with C. pepo. The most refractory barrier was achieving homozygosity for ZYMV resistance. Disturbed segregation occurred in succeeding generations and the progeny of most resistant plants segregated and were not uniform for resistance. This and other barriers to interspecific gene exchange were overcome and a summer squash variety homozygous for resistance to ZYMV, PRSV, and CMV is being released this year.

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Three classes of crosses using four genotypes of V. riparia (wild Riverbank grape) as maternal parents were evaluated for evidence of reproductive expression of genetic incongruity. The classes were: I V. riparia x V. vinifera cultivars (European domesticated grape); II V. riparia x French Hybrids (complex interspecific hybrids); III V. riparia x V. riparia. Percent fruit set and seeds per berry were recorded for two years. If incongruity is a factor in interspecific grape crosses, then the values for these traits would be expected to be lower in classes I and II than in class III. Analysis of variance indicated significant differences for some half-sib families. Fruit and seed set were lower in classes I and II than in class III, suggesting that incongruity is operative in wide grape crosses. In the process of creating French hybrids, genomes of several species came together over generations of hybridization. In concert with selection for fertility, repeated interspecific genomic exposure would be expected to have ameliorated the effects of initial incongruity between American species and V. vinifera, increasing their value as genetic bridges in breeding programs.

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