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Kim Hummer and Donna Gerten

In commercial growing regions the bloom period for currants and gooseberries is critical to crop development because of potentially damaging spring frosts. Breeding programs in northern latitudes include selection for frost avoidance mechanisms such as late blooming tendencies. Corvallis climate is milder than Ribes production regions, with the average winter minimum temperature about 10C and the coldest recorded April temperature of -5C in 1926. The last spring frost occurs by April 14 on average. About 30 cultivars and species selections of currants and about that same number of gooseberries were evaluated for blooming and fruiting at the National Clonal Germplasm Repository. Dates of first bloom, last bloom, first ripening, and last ripening during 1987 through 1989 were collected. The longest ripening period, 93 days, occurred in 1989 on a selection of R. burejense F. Schmidt. The shortest ripening period in 1989 was 70 days, occurring in many black currant cultivars including Black September, Crusader, Coronet, and Invigo. These same cultivars required a range from 62 to 66 days to ripen m 1987. For the years examined thus far, the earliest ripening dates occurred in 1987, starting as early as Julian date 150; the latest ripening date (192, Julian) occurred in 1988. Data from 1990 will be presented. The climate in the Pacific Northwest is favorable for the production of currants and gooseberries.

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Jaime Javier Martínez-Téllez

Almond production is restricted to areas with at least 300 chill units. Selection of plants with lower chilling requirements is a priority in our area. The progenies of two low chilling cvs. `Rané' and `Constantini' and one of medium chilling cv. `Cavaliera' were chosen for this study. The selected trees were open pollinated and 100 seeds of each variety were planted on individual pots after three week stratification. Three groups were formed according to the speed of germination and transplanted to the nursery. The date of blooming of each individual was recorded. A positive correlation was found between time of blooming of the progenitor and that of the progeny regardless of the origin. On the descendence of `Cavaliera', a positive correlation between speed of germination and bloom date was observed. However on `Constantini' and `Rané' progenies, the same correlation had no significance. `Cavaliera' produced a 45% of low chilling requirement descendants, `Rané' had 67% and `Constantini' had the higher ability to transmit the low chilling character with a 78% of the progeny with that trait.

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Allen Owings, Gordon Holcomb, Anthony Witcher, Allen Broyles, and Edward Bush

All-American daylily cultivars named from 1994–2004 were evaluated for landscape performance and daylily rust (Pucciniahemerocallidis) susceptibility during 2003 and 2004. Cultivars included `Black-Eyed Stella', `Bitsy, `Leebea Orange Crush', `Plum Perfect', `Judith', `Starstruck', `Frankly Scarlet', `Lullaby Baby', `Lady Lucille', and `Chorus Line'. Bareroot plants were planted in raised beds composed of an Olivier silt loam soil in full sun and received irrigation as needed to prevent stress. Visual quality ratings were made weekly from 19 Apr.–25 Oct. 2003 and 15 Mar.–20 Sept. 2004. Visual quality ratings included growth habit, based on compactness, foliage color, uniformity, and overall aesthetics, and flowering, based on longevity and visual appeal. Other flower observations were made in regard to time in bud and peak blooming periods over the same time frames. Flowering observations indicated that `Black Eyed Stella' and `Bitsy' were the only cultivars showing reliable repeat bloom potential. Among the other cultivars, `Judith' was the earliest to bud and bloom, but also had a blooming period of only 2–3 weeks compared to 4–5 weeks of bloom for other cultivars. Daylily rust ratings were taken in Sept. and Nov. 2003 and in Aug. and Nov. 2004. Rust was most severe on `Judith', `Leebea Orange Crush', `Starstruck', and `Lady Lucille'. `Judith' and `Leebea Orange Crush' showed rust symptoms earlier than other cultivars. `Plum Perfect', `Frankly Scarlet', `Bitsy', `Black Eyed Stella', and `Lullaby Baby' were least susceptible to daylily rust.

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Warner Orozco-Obando, Gwen N. Hirsch, and Hazel Y. Wetzstein

The general doctrine of flowering in Hydrangea macrophylla (Thunb.) Ser. is that floral induction occurs during the fall months with the flower appearing the following spring or summer. However, hydrangea cultivars differ widely in their relative abundance and duration of flower production. The objective of this study was to determine how developmental flowering patterns compared among different hydrangea genotypes. Flowering was characterized in 18 cultivars by assessing flower initiation in dormant buds of 1-year-old stems that received natural outdoor inductive conditions. Terminal and lateral buds were dissected and floral developmental stage categorized microscopically. In terminal buds, flower development was very consistent and occurred in 100% of buds for all cultivars except `Ayesha' (33%). In contrast, lateral buds showed a wide variation in flower induction among genotypes. `Ayesha', `Blushing Pink', `Freudenstein', and `Nigra' had 10% or fewer lateral buds with floral initials. `All Summer Beauty', `David Ramsey', `Masja', `Nightingale', and `Penny Mac' showed high levels of floral induction (>92%). Within a cultivar, flower development was more advanced in terminal than lateral buds. In several cultivars, a significant correlation between bud size (length) and floral stage was found. However, low r-square values indicated that flower stage was explained largely due to factors other than bud length. This study shows that floral induction patterns vary markedly among hydrangea cultivars and provides insight into why cultivars differ in the extent and reliability of seasonal blooming. Genotypes that possess floral primordia in lateral buds would be amenable to cultural practices that enhance lateral budbreak and recurrent blooming.

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R. A. Criley and S. Lekawatana

More than three dozen species of Heliconia have entered the cut flower trade since the expanded interest in bold tropical cut flowers began in the early 1980s. Most were wild-collected originally with little information on their habitats or season of bloom. A natural flowering season for some species can be found in the taxonomic literature, but it may be influenced locally by rainfall and drought periods as well as by photoperiod and therefore not reliable in indicating production periods in Hawaii. Sales records from 1984 through 1990 or several heliconia growers on Oahu reflected not only the quantities produced but also the time and duration of the blooming season. Such information is helpful in coordinating with the flower markets. Heliconia species of commercial interest with strong seasonal flowering periods are noted: angusta, bihai, caribaea, caribaea X bihai, collinsiana, farinosa, lingulata, rostrata, sampaioana, stricta, subulata, wagneriana.

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J. Phillip McKnight and G. L. Klingaman

Eighteen New Guinea impatiens cultivars were evaluated for performance as bedding plants and for suitability as hanging basket plants. The cultivars were treated with three growth retarding chemicals (B-9, Sumagic and Cutless) to determine their effect on plant growth, branching and overall flower development. Two applications of 2500 ppm B-9 produced the most commercially acceptable plants. Height and spread were reduced by approximately 30 percent with no reduction in the number of flowers produced or the number of days to bloom. Cutless and Sumagic applications reduced growth approximately 50 percent and delayed blooming as much as 2 weeks when compared to the untreated control. Growth regulator treatment had no effect on the number of branches produced except with Sumagic which resulted in an overall reduction in branching.

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Margaret R. Pooler and Ruth L. Dix

Interspecific hybridizations among members of the genus Hamamelis (the witchhazels) and Corylopsis were carried out in 1993, 1994, 1995, and 1996 at the U.S. National Arboretum. Specifically, crosses involving the native witchhazel (H. vernalis and H. virginiana) and the Asian taxa (H. mollis, H. japonica, and H. × intermedia) were attempted in order to combine the ornamental qualities of the Asian species with the adaptability and fall blooming characteristics of the native species. Additionally, C. platypetala, a hardy species with small inflorescences, was crossed with C. himalaica, which has large showy inflorescences but is less hardy. Approximately 50 seedlings resulting from these crosses have been analyzed using randomly amplified polymorphic DNA (RAPD) markers to verify interspecific hybridization. Based on these assays, we report the first incidence of controlled interspecific hybridization between the Asian and native witchhazel taxa.

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Alan R. Biggs

The proportion of spurs blooming on `McIntosh' apples (Malus domestica Borkh.) was reduced significantly in 1986 and 1988, but not in 1987, following seasonal programs of six bitertanol or flusilazole treatments applied at two and three rates, respectively. The fungicides were not associated with any visible phytotoxic effect nor was shoot length reduced by any fungicide treatment. In two of three experiments conducted in May and June 1986, transpiration was reduced by the low rate of flusilazole and the high rate of bitertanol relative to both the captan and nonsprayed trees. In all three experiments, flusilazole at 1.4 g a.i./100 liter was associated with transiently reduced transpiration rates, lasting a minimum of 48 hours, relative to the nonsprayed control. Fungicides affected the diffusive resistance of apple leaves in all three experiments; however, there were no consistent treatment effects on diffusive resistance among the three experiments.

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Lijuan Wang, Nian-Oine Shi, Murray E. Duysen, and Chiwon W. Lee

Cleistogamy in Salpiglossis sinuatu L. involves a sequence of events, including arrested corolla development, precocious pollen germination inside anther, pollen tube penetration of the pistil, and eventual self fertilization, that takes place. within a tightly closed flower bud. A single dominant gene (C) controls cleistogamy in this plant. During early blooming period, cleistogamous (CC, Cc) plants produce both chasmogamous (open) and cleistogamous (closed) flowers. Enzymes in various tissues of both cleistogamous and chasmogamous buds were detected by isozyme banding patterns in starch gel electrophoresis. The onset of cleistogamy may be signalled in the calyx and corolla tissues in the early stage of flower development. The levels of specific enzymes (PGM, PGI, G-6PD, PGD, MPI) involved in gluconeogenesis, pentose phosphate shunt and glycolysis in both calyx and corolla tissues of the cleistogamous buds were greatly reduced. These enzymes were present in the pistil and anthers of cleistogamous buds and in all floral parts of the chasmogamous buds.

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T.G. Beckman, W.R. Okie, and S.C. Meyers

Rootstock influence on bloom date and fruit maturation of `Redhaven' peach [Prunus persica (L.) Batsch] was studied over a 3-year period. Rootstock included seedlings (Lovell, Halford, Bailey, and Siberian C) and cuttings (GF677, GF655.2, Damas 1869, and `Redhaven'). Bloom dates of the various combinations differed in all 3 years, with a range of 3.6, 9.1, and 7.3 days in 1988, 1989, and 1990, respectively. Fruit development period differed each year with a range of 3.9, 5.8, and 4.4 days in 1988, 1989, and 1990, respectively. `Weighted-average harvest date also differed with a range of 3.6,2.9, and 5.6 days in 1988, 1989, and 1990, respectively. `Redhaven'/Lovell was the latest blooming and maturing combination in all 3 years of the study.