On March 13-15, 1993 Alabama and much of the eastern United States experienced an unusually severe winter storm. This afforded the evaluation of plum cultivar production under cold stress. The highest yielding variety that bloomed before the storm was Bruce 12-4 with 28 kg/tree. Bruce 12-4 is noted for blooming over an extended period of time and producing very heavy yields. The average yield of the top five performers that bloomed after the storm was 51 kg/tree. The lowest temperature recorded at the test site, Shorter, AL was -5C.
Current lilac breeding programs at the University of New Hampshire focus on the later (June) blooming species of Syringa with goals of extending the season of bloom selecting slower growing forms and developing lines with double flowers. Progress toward these goals and others, e.g., true dwarfs, will be discussed and illustrated.
Every university in the northeast includes woody ornamentals in its program to some degree. The University of New Hampshire is an official test site for ornamental from NE-9 and NC-7 germplasm programs and the National Arboretum's new introduction program. The value of these programs and their future direction will be discussed.
Abstract
Differences in pistil abortion did not account for variation in fruiting among ‘Manzanillo’ (biennal bearing), ‘Rubra’ (regular cropping), and ‘Swan Hill’ (strong blooming but unfruitful) olives (Olea europaea L.). Competition among normal fruits in an inflorescence seems to be a main factor in regulating final crops. Parthenocarpic fruit of ’Manzanillo’ and ‘Swan Hill’ did not exhibit fruit competition. A high percentage of ovules in ‘Swan Hill’ contained poorly developed embryo sacs at anthesis and were not fertilized. Most of the few parthenocarpic fruit formed eventually shriveled and abscised.
Abstract
Removal of bud scales hastened bud burst of several early and late blooming apple cultivars. Descaling was most effective during the onset and end of rest. During deep rest, bud scale removal was effective only when applied 2 weeks before forcing conditions. Extracts of bud scales inhibited apple bud break in vitro. Abscisic acid (ABA) may have been responsible for part or all of this bioactivity, since ABA occurred in bud scale diffusates and could replace or reinforce the bud scales in vitro. Wound-produced ethylene was not involved in the bud scale removal response.
This paper describes the climatic and cropping conditions in the major peach [Prunus persica (L.) Batsch] producing areas in the southeastern United States in 1996. The peach and nectarine crop was the smallest since 1955 due to a series of unusually cold temperatures in February, March, and April. Crop set was not strictly a function of late blooming. No variety produced a full crop across the region. Many reputedly hardy peaches cropped poorly. The only peach or nectarine varieties that produced substantial crops in multiple locations were `La Premiere', `Ruston Red', and `Contender'. Cropping ability of some breeding selections shows that peach frost tolerance may be improved further.
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.
Abstract
Hybrid lisianthus [Eustoma grandiflora (Raf.) Shinn.] was evaluated as cut flower and flowering pot plants. Lisianthus is a day neutral summer blooming plant blooming earlier at high growing temperatures (18°/26°C night/day) than at low temperatures. It is a slow growing plant, requiring about 5 to 6 months from sowing to flowering. Forcing period is about 2 months. Three color variants are available: blue, pink, and white. Only the blue and white are suitable as cut flowers. About 3 cut flower stems are produced per plant in the 1st harvesting cycle, and retaining the plant for a 2nd crop is considered uneconomical. Keeping quality of the cut flowers can be improved by pulsing for 24 hr with a solution containing 5% to 10% sugar, and desirable blue and pink pot plants were obtained by spraying with butanedioic mono-2.2-dimethylhydrazide (daminozide, B-Nine). The white cultivar did not respond to daminozide but did respond to soil application of a-cyclopropyl-a-(p-methyoxyphenyl)-5-pyrimedine methyl (ancymidol). Flowering pot plants should be grown in the greenhouse until about half of the flower buds on the plants open, since buds do not develop properly under home conditions.
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.
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.
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.