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Roger J. Sauve, Suping Zhou, Yingchun Yu, and Wolfram George Schmid

A randomly amplified polymorphic DNA (RAPD) technique was used to identify and determine the phylogenetic relationships of 37 hosta accessions representing the major subgenera, sections and groups in the genus Hosta. Results of this study show that RAPD markers were able to differentiate not only the main groups, whose plants shared many genetic traits, but also cultivars within a species. Some accessions were identified by a single primer while others had high intercross linkage and required many markers for their separation. The phylogenetic clustering showed that H. plantaginea, the only night-blooming species, and H. ventricosa, the only known natural tetraploid, are unique and should be classified separately. The four species in the subgenus Bryocles, section Lamellatae H. venusta, H. minor, H. capitata, and H. nakaiana have very low genetic similarity since they do not share many amplified fragments. The other accessions were classified into four main clusters; cluster 1: H. venusta, H. tardiva, H. pycnophylla, H. tsushimensis `Ogon', H. montana, H. tibae, H. montana f. macrophylla, H. kikutii `Kikutii', H. longissima `Longifolia', H. rectifolia `Rectifolia', H. takahashii and H.`Undulata'; cluster 2: H. laevigata, H. sieboldiana, H. pycnophylla × H. longipes f. latifolia, H. longipes `Urajiro' and H. ibukiensis; cluster 3: H. capitata, H. kikutii `Polyneuron', H. nigrescens, H. kikutii `Yakusimensis', H. pachyscapa, H. kikutii `Caput-Avis', H. longipes f. latifolia, H. hypoleuca, H. okamotoi, H. densa and H. takiensis; and cluster 4: H. aequinoctiiantha, H. rupifraga, H. `Amanuma', H. minor and H. kikutii `Densa'.

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Rebecca Kincaid* and Tracy Dougher

There has been an increasing interest in drought tolerant native flower species for Montana residential landscapes and roadsides. Ratibida columnifera is a drought tolerant, perennial wildflower that can be used in home gardens as well as on roadsides. However, there is no knowledge of how R. columnifera will respond to typical nitrogen fertilization in residential landscapes. Our objective was to determine the correct nitrogen application required for R. columnifera to acquire optimal growth and development. After germinating and transplanting R. columnifera seedlings, nitrogen treatments began with five groups containing six pots in each group. Pots were fertilized with 100 ml of ammonium nitrate at 0ppm N, 25 ppm N, 50 ppm N, 75 ppm N, or 100 ppm N at weekly intervals. All pots were fertilized with 100 mL of 50 ppm potassium phosphate. Three plants from each treatment were harvested 30 days after the start of fertilization treatments and underwent biomass evaluations of their fresh and dry weights. The remaining three pots from each treatment were evaluated at blooming for time to flowering, flower number, and flower quality. R. columnifera biomass at 30 days benefited from 25-50 ppm nitrogen, but did not increase biomass above 50 ppm. Flowering was affected at different levels than biomass and was delayed by high nitrogen.

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Jiunn-Yan Hou, Wei-Li Lin, Nean Lee, and Yao-Chien Alex Chang

Phalaenopsis flowers are prone to wilting under ethylene (C2H4) stress. 1-Methylcyclopropene (1-MCP) can protect Phalaenopsis flowers against ethylene injury. In this study, we determined the residual effect of 1-MCP and how it is affected by temperature. The efficacy of multiple applications of 1-MCP was also investigated. The residual effect of 1-MCP was determined by pretreating blooming Phalaenopsis amabilis plants with 0.8 μL·L−1 1-MCP for 8 hours on Day 0 followed by 2 μL·L−1 ethylene fumigation for 12 hours on designated days. Without 1-MCP pretreatment, flowers began to wilt within 2 days after exposure to ethylene. Duration of the residual protection of 1-MCP on P. amabilis was ≈6 to 8 days during summer in Taiwan. Lower temperatures after 1-MCP application prolonged protection times. The full protection times under day/night temperatures of 25/20, 20/15, and 15/13 °C were 4 to 8, 10 to 13, and 13 to 17 days, respectively. Furthermore, multiple applications of 1-MCP extended the duration of 1-MCP protection against ethylene. Three applications increased the residual protection of P. amabilis by 1-MCP to at least 24 days.

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Gerard Krewer, D. Scott NeSmith, and Ben Mullinix

`Climax' blueberry is a major cultivar in Georgia, but because of its excessively low chilling requirement and early blooming habit, it has a poor cropping history in recent years due to spring freezes. Research was initiated to explore the potential for ethephon to delay bloom, without delaying ripening too much. In 1997-1998 a treatment of 200 ppm ethephon applied on 3 Nov. or 400 ppm applied on 17 Nov. delayed bloom 5 to 7 days compared to the control. There was no significant difference between the control and the ethephon treatment in flower bud density or fruit density in the spring. In 1998-1999 ethephon applications at 200 and 400 ppm were applied once or twice 2 weeks apart starting on 5 Oct. and ending 19 Nov. A bloom delay of about 7 days was achieved with most ethephon applications. However, an application of 400 ppm on 19 Oct. and 2 Nov. delayed bloom about 14 days compared to the control. There was a trend toward delayed fruit ripening with the most-effective bloom delay treatments, but the extent of delayed ripening was minimal. Berry weight was not effected by ethephon treatments.

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Maria Cantor

Gladiolus is one of the most popular flower crops grown in Romania. The breeding program at the University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca of this species has been especially focused on the improvement of main characteristics, such as color, number and form of florets, plant height, multiplication capacity, diseases resistance, etc. A program for genetic breeding of gladiolus varieties using different genitors (Romanian and foreign cultivars) was initiated. An intraspecific crossing between cultivars has been made followed by clonal selection and vegetative multiplication of the selections. In this paper, we show 15 new gladiolus selections, which were observed and analyzed in 2004–05. The selections obtained have a great uniformity of their morphological characteristics. These selections are more vigorous, producing greater number of florets with superior quality, have new colors of flower, and are distinguished by a long blooming time. The intraspecific variability of the above-mentioned characteristics was more than low, and rarely medium, high, or very high. These data suggest fair possibilities to choose the best selections that will be proposed for testing and homologation as new cultivars. The hybrids represent a step forward in combining high qualities in gladiolus. They will contribute to improving the assortment of gladiolus for cut flowers, landscape, or as genetic material, which can be used for new crossing in order to obtain new cultivars. Scientifically, a series of findings appeared considering the combining capacity of genitors, transmission of some useful qualities, and other aspects that contribute to improve of the new varieties.

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Bob Bors and J. Alan Sullivan

Fragaria vesca has been introgressed into F. ×ananassa in the form of decaploids and synthetic octoploids. As F. vesca is self-incompatible and crosses with most diploid Fragaria species when used as a female parent, it could serve as a bridge for introgression of additional genetic material. A primary goal of this study was to screen selections of F. vesca for interspecific crossability among diploid species. The F. vesca collection included 10 cultivars of the alpine strawberry, F. vesca var. semperflorens, as well as 30 wild runnering types gathered from around the world. The following diploid species were represented by one to three genotypes each: F. viridis, F. nubicola, F. nipponica, F. nilgerens, F. iinumae, F. daltoniana, F. gracilis, as well as two unnamed species from China. Fragaria vesca was used as the female parent and the other species provided the pollen. Crossing took place in the greenhouse, with one pollination occurring during the “popcorn” or “balloon” stage. Germination was performed in vitro using cut achenes shortly after fruit ripening. The alpine strawberry cultivars were easier to cross than wild selections of F. vesca. Their continuous blooming habit combined with higher positioning of flowers allowed for easier and perhaps less-damaging emasculation. Crossability, as measured by seed set and germination, was more variable in wild-type F. vesca and generally lower than alpine strawberry cultivars.

Free access

Preston K. Andrews and Margaret L. Collier

Variability in maturity and quality of sweet cherry (Prunus avium L. `Bing') fruit at harvest is a major limitation to the crop's storage and marketing potential. Later blooming flowers resulted in poorer fruit quality Differences in bloom date were related to differences in flower primordial development during winter. Vigorous shoots grown in the previous season produced fewer flower buds per length of shoot than did shorter, less vigorous shoots, resulting in larger flower primordia on vigorous shoots, The effects on primordial and fruit development of altered leaf areas per flower bud the previous summer were examined. A decrease in leaf area per bud during summer reduced primordium size in mid-winter. Dormant flower primordia of 6-yr-old `Bing' trees on precocious `Giessen' rootstock, Gil48/1, were larger than those with `Mazzard' as rootstock. Flower primordia on dwarfing Gil48/8 rootstock were intermediate in size. Differences in primordial development and bloom date, whether due to management practices or rootstock, may affect fruit development and contribute to variability in fruit maturity and quality.

Open access

Yaser Hassan Dewir, Abdullah Alsadon, Abdullah Ibrahim, and Mohammed El-Mahrouk

Hydroponics is a promising method for cultivation of saffron (Crocus sativus). In this study, saffron corms were sprouted using a gradual decrease in air temperature, and they were cultivated hydroponically in either perlite or volcanic rock for 24 weeks. A nutrient solution was supplied using either an ebb-and-flow system or continuous immersion. First blooming was observed 29 days after transplantation. Among flowering traits, only the stigma length was significantly influenced by the type of hydroponic system. Saffron plants displayed better growth parameters, a higher photosynthetic rate and stomatal conductance (g S), as well as daughter corm (cormlet) production under the continuous immersion system, in comparison with the ebb-and-flow system. Small corms (22–25 mm diameter) did not bloom, and the emergence of flowers increased with corm size. Plant growth and photosynthetic parameters, as well as cormlet production, significantly increased with corm size. We obtained the highest stigma yield [number of flowers (1.9), stigma length (39.4 mm), stigma fresh (42.8 mg), and dry weight (5.3 mg)] and cormlet yield [number of cormlets (5.7), average corm diameter (25 mm), and fresh weight (6.4 g)] using mother corms sized ≥32 mm diameter grown hydroponically in the volcanic rock–based continuous immersion system.

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.