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Open access

Sandra B. Wilson, Carlee Steppe, Zhanao Deng, Keri Druffel, Gary W. Knox, and Edzard van Santen

Trailing lantana [Lantana montevidensis (Spreng.) Briq.] is a low-growing, woody ornamental valued for its heat and drought tolerance and repeat blooming of purple or white flowers throughout much of the year. In 2011, trailing lantana was predicted to have high invasion risk by the UF-IFAS’s assessment of non-native plants in Florida, and therefore it was no longer recommended for use. All cultivars fall under this designation unless proven otherwise. Eight trailing lantana varieties were obtained from wholesale growers or naturalized populations found in Texas and Australia. Plants were propagated vegetatively, finished in 4-inch pots, and planted in field trials located in central (Balm) and northern (Citra) Florida. Throughout the 24-week study from June to November, mean plant quality was between 4.4 and 4.7 (on a 1 to 5 scale) for U.S. varieties and 3.9 for the Australian form. Mean flowering was between 4.1 and 4.5 (on a 1 to 5 scale) for U.S. trailing lantana varieties and 3.5 for Australian trailing lantana. Australian trailing lantana differed from other U.S. varieties tested, being smaller in size, more sensitive to cold, and having a high female fertility index (producing abundant fruit with viable seed per peduncle). Our findings indicate that some U.S. varieties of trailing lantana are unlikely to present an ecological threat and merit consideration for production and use.

Open access

K. (Brainerd) Hummer, H.B. Lagerstedt, and S.K. Kim

Abstract

Stem sections of 31 filbert genotypes were collected, artificially frozen, and evaluated by visual browning of cambium and other tissues to determine cold hardiness during 5 sample dates in 1984 and 1985. Corylus heterophylla Fish. ex. Trau. was the most cold-hardy filbert tested, but it deacclimated sharply before the end of February. The tested filberts were divided into 3 temporal groups of acclimation to maximum cold hardiness—early, midwinter, and late. C. avellana L. ‘Butler’, ‘Tombul’, ‘Barcelona’, ‘Ennis’, and ‘Casina’ acclimated early; ‘Gasaway’, acclimated in midwinter season; ‘Daviana’ and ‘Hall’s Giant’ acclimated late. The genotypes tested also were separated into very hardy, hardy, and least hardy groups for cortex-cambium, pistillate bud, and staminate bud tissues. The general order of tissue hardiness from least to most was pith, xylem, cambium, and cortex. Vegetative buds in midwinter were as hardy or hardier than the cambium. Staminate flowers were hardier than pistillate in October, but most pistillate flowers were hardier than staminate by January. Several filberts had fully blooming pistillate flowers that were uninjured at −30°C in December and −40° in January. Filbert flower buds demonstrated maximum cold hardiness during nondormancy.

Open access

Eric J. Hanson and P.J. Breen

Abstract

Foliar B sprays (500 ppm) applied in the fall to ‘Italian’ prune (Prunus domestica L.) trees had no effect on fruit set in a warm spring when set was high (average, 12.2%), but increased fruit set by 32% in a cool spring when set was low (3.2%). Fall B sprays increased flower B levels and decreased pistil length, but had no effect on the rate of pollen tube growth through styles in the cool spring. Calcium sprays (0.5 m) applied in the fall prior to the cool spring did not affect fruit set, pistil length, pollen tube growth or flower Ca or B levels. Flowers on cut branches forced indoors accumulated as much B as those on intact trees, indicating that flowers are supplied B from reserves in nearby branches. Simulated rain did not leach B from flower buds readily. Flowers blooming on excised branches in high relative humidity (86%) contained 13% less B per flower than flowers in low humidity (29%). The amount of set and B concentrations in flowers in a given year may influence the response to fall applied B.

Open access

J.R. Ballington, Y.M. Isenberg, and A.D. Draper

Abstract

Hexaploid Vaccinium hybrid progenies, including F1, F1 intercross, F1 × F2, BC1, BC1 intercross, and BC1 × F2 crosses between V. ashei Reade and V. constablaei Gray, and an intercross between late-blooming V. ashei genotypes, established in the commercial blueberry production area in eastern North Carolina, were compared among themselves and with 2 highbush blueberry (V. corymbosum L.) cultivars for flowering, ripening, primary mummy berry infection, crop, and fruit characteristics. There were significant differences among progenies for all traits, with sufficient variability for selection within most progenies. Differences reflected specific parent combinations rather than type of cross with the V. ashei–V. constablaei derivative progenies. The experiment included both V. ashei and V. ashei–V. constablaei derivative progenies that produced a high percentage of seedlings flowering with or later than highbush blueberries. Two percent of the V. ashei–V. constablaei derivative seedlings bloomed and ripened with the early ripening highbush cultivar ‘Croatan’. Crop ratings were variable in all progenies, and high sds for the cultivars indicated that a high percentage of the variation was environmental. Primary mummy berry infection significantly reduced the crop in several progenies but was not responsible for the poor overall crop performance of most. Mean fruit size of the V. ashei intercross was large enough for hand harvest, while all but the 2 smallest-fruited V. ashei- V. constablaei derivative progenies were large enough for mechanical harvesting. Fruit of most progenies were commercially acceptable for color, picking scar, firmness, and flavor.

Free access

Rafel Socias i Company, Ossama Kodad, José M. Ansón, and José M. Alonso

The almond ( Prunus amygdalus Batsch) breeding program of the Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA) of Aragón aims to develop new self-compatible and late-blooming cultivars to solve the main problem detected in

Free access

Christopher L. Owens, J.F. Hancock, and A.F. Iezzoni

Sour cherry and strawberry are examples of two Rosaceous species that often suffer crop reductions due to spring freezes. Breeding for improved floral freezing tolerance has the potential to mitigate the susceptibility of these plants to spring frosts. In model plant systems, researchers have been able to identify genes that play a role in freezing tolerance by initially searching for mRNAs regulated in response to cold temperatures. To search for cold-responsive freezing-tolerance genes in strawberry and sour cherry, it is necessary to first define their cold acclimation response. To test the hypothesis that sour cherry and strawberry flowers have the ability to cold acclimate, blooming plants were exposed to 4 °C and 16 h light for 14 days. Sour cherry styles and strawberry receptacles from open, fully developed flowers were excised, and electrolyte leakage curves were generated over a range of subzero temperatures. The temperature at which 50% electrolyte leakage (EL50) occurred was used to compare treatments. The flowers of two strawberry cultivars were tested for the ability to cold acclimate. Non-acclimated `Chandler' receptacles had an EL50 of -2.9 °C, while non-acclimated `Honeoye' had an EL50 of -3.4 °C. Conversely, acclimated `Chandler' receptacles had an EL50 of -7.7 and acclimated `Honeoye' receptacles had an EL50 of -8.7 °C, both are significantly different from non-acclimated values (P ≤ 0.01). Additionally, sour cherry styles were collected from the field at full bloom from a mapping population of 86 individuals from the cross `Rheinische Schattenmorelle' × `Erdi Botermo' and acclimated as previously described. The EL50 of the 86 progeny ranged from approximately -2.0 to -6.0 °C.

Free access

Dennis Deyton, Carl E. Sams, Jim R. Ballington, and John Cummins

Trials were conducted in 2004 to compare the effects of soybean oil formulations and concentrations on flowering and fruit thinning of rabbiteye and southern highbush blueberries. Mature `Climax' bushes near Spring City, Tenn., were sprayed to runoff on 10 Feb. with water, or 9% soybean oil in the formulations TNsoy11, TNsoy12, TNsoy13, TNsoy14, or Golden Natur'l (GN). In a second trial, 3-year-old `Legacy' southern highbush plants at Spring Hill, Tenn., were sprayed on 11 Feb. with 0%, 6%, 9%, 12%, and 15% GN. A similar trial was sprayed on 5 Mar. at Fletcher, N.C., using young plants of various Southern highbush cultivars. Each formulation of soybean oil (9%) delayed bud development and flower anthesis of `Climax' bushes. Bloom opening on `Legacy' bushes was delayed by 2 to 6 days with sprays of ≥9% GN, with higher concentrations causing more delay. However, flower bud mortality of `Legacy' plants was greater when sprayed with the higher oil concentrations. `Legacy' plants sprayed with 0%, 6%, and ≥9% oil had 0%, 30% and ≥70% bud mortality, respectively, at 36 days after treatment. `Legacy' plants sprayed with 12% and 15% oil sprays had an estimated 24% and 13%, respectively, of a crop load compared to the estimated 100% crop load on control plants. Flower bud development, flower bud mortality, crop load and berry size (across cultivars) of Southern highbush cultivars at Fletcher were not affected by oil treatments. Results were variable among trials, perhaps due to factors such as cultivars, timing of application (date), maturity of plants, environmental conditions, etc. There is potential for soybean oil formulations to be used as a chemical thinner as well as to delay blooming.

Full access

Chiwon W. Lee

Velvet flower (Salpiglossis sinuata, Solanaceae) can be used as an excellent demonstration plant for horticultural crop breeding classes. Salpiglossis produces large trumpetlike flowers exhibiting an assortment of corolla colors and pigmentation patterns. The pistil is large (3 to 4 cm or 1.2 to 1.6 inches long) with a sticky stigmatal tip and flowers can be easily emasculated prior to anthesis. The large pollen grains are shed in tetrads which can be separated and placed on the stigmatal surface. It takes eight to nine weeks from seeding to blooming, with a prolific flowering cycle that comes in flushes. Numerous seeds (about 750 per capsule) are obtained in three weeks after self- or cross-pollination. The influences of three genes that control flower color and pigmentation pattern can be conveniently demonstrated with their dominant and recessive alleles. The R gene controls flower color with red (RR or Rr) being dominant over yellow (rr). The D gene controls the density of pigmentation with solid (DD or Dd) color being dominant over dilute (dd) color. Corolla color striping is controlled by the St gene with striped (stst) being recessive to nonstriped (StSt or Stst) pattern. By using diploid lines of genotypes RRDD (red, solid), RRdd (red, dilute), or rrdd (yellow, dilute) and their crosses, students can easily observe a dominant phenotypic expression in the F1 hybrid and the digenic 9:3:3:1 segregation ratio in the F2 progeny. Another gene (C) that controls flower opening can also be used to show its influence on cleistogamous (closed, selfpollinated, CC or Cc) versus normal chasmogamous (open-pollinated, cc) corolla development. In addition, the induction and use of polyploid (4x) plants in plant breeding can also be demonstrated using this species.

Free access

Heidi A. Kratsch

Alnusmaritima may have potential for use in home and commercial landscapes in northern Utah. This fast-growing, fall-blooming shrub is cold-hardy to USDA hardiness zone 3b and tolerant of nutrient-poor soils and full sun. Because this taxon is native to low-elevation wetlands, I seek to determine its response to the high desert soils and climate of northern Utah. My specific objective was to test germination and survival of plants from seed sowed in three diverse soil types typical of the Wasatch front in north-central Utah. Seeds were rinsed with distilled water and cold-stratified in darkness for 16 weeks between wet filter paper in sealed petri dishes. Stratified seeds were sowed in flats filled with soil from each of three sites at the Utah Botanical Center in Kaysville and held in a greenhouse. Seeds planted in flats filled with soilless germination mix served as controls. Flats with 60 seeds were experimental units, and each medium was replicated three times. Soils ranged from silty loam to loam, nitrate-N was 3.2 to 5.4 mg·kg-1, and there was 1.4% to 2.9% organic matter. Germination rates were highest in the soilless mix (50%). Of the three soil types, the highest germination rates (24%) occurred in a loamy soil high in organic matter (2.9%). Rates were similar (12.5% and 13%) in the other two soils. Seeds of A. maritima can germinate in soils typical of urban landscapes in northern Utah, so both the potential for invasiveness and the performance of plants in the landscape of northern Utah are being evaluated.

Free access

R.E. Moran, S.M. Southwick, K.G. Weis, and B. Lampinen

Secondary or “rat-tail” bloom, a major site for fireblight infection of `Bartlett' pear, comprised 10% of the total bloom in 1997 and 20% in 1998. We are striving to find production practices that can be economically applied to reduce the number of “rat-tails.” Of the five known types of secondary clusters in pear, four occur on `Bartlett', the most numerous being types I and V. Type I rat-tails occur on the bourse at the base of normal clusters and bloom from 10 to 30 days after normal bloom. Type V rat-tails occur mostly at pruning sites and have one to three flowers per cluster, blooming 20 to 50 days after normal bloom. GA 3 or GA4+7 + BA were applied at 100 mg•L-1 in 1997 to reduce rat-tail bloom in 1998. In 1998, neither GA3 nor GA4+7 + BA had an effect on normal bloom or type I rattails. GA3 reduced type V rat-tails when applied at either 2 June, 2 July, or 15 Aug. but had no effect on type V clusters when applied at full bloom, petal fall, 16 June, or 15 July. GA4+7 + BA reduced the number of type V rat-tails when applied at either 2 June, 16 June, 2 July, and 15 July but had no effect when applied at full bloom, petal fall, or 15 Aug. Dormant pruning horizontal shoots resulted in as many rat-tails as vertical shoots, and heading cuts a similar number as stubbing cuts. Dormant pruning 1-year wood resulted in fewer rat-tails than 2-year wood. Summer pruning 21 or 49 days after bloom resulted in fewer rat-tails than pruning 10 days after harvest, but was similar to pruning 89 days after bloom. These and other results from ongoing work will be presented toward development of an integrated fire blight reduction strategy.