Coreopsis species (tickseed) can be regenerated from leaf segments allowing the possibility to exploit somaclonal variation as a means to develop novel phenotypes. We used true leaf explants from in vitro seedlings of perennial C. grandiflora (A. Gray) Sherff `Domino' and `Sunray' grown on Murashige and Skoog (MS) basal medium. Two of ten seedlings of `Domino' regenerated freely and others were generally recalcitrant. From these two seedlings, designated E2 and H2, shoots were regenerated and acclimatized to the greenhouse. About 175 plants were established and vernalized from which somaclones were selected based on distinct differences in flower orientation and appearance. The selected somaclones were propagated by division and transplanted to the field in August 2001 in a randomized complete block design with three-plant plots and three replications to determine whether novel characteristics persisted through an additional propagation cycle. In the field, plant height, leaf dimension, flowering, and flower dimensions were scored in June and July 2003. Differences were found between somaclones and similarly propagated E2 and H2 for desirable (more petals per flower, greater flowering, shorter plants), undesirable (less flowering, smaller flowers), and neutral (narrower leaves, taller plants) traits. Open-pollinated (OP) seed was collected and germinated and the seedlings from somaclones that differed significantly from E2 and H2 were evaluated. These maternally selected seedlings were overwintered then planted in the field in May 2004. Most traits that differentiated somaclones from E2 and H2 did not persist in the OP seedling population; however variation that was likely introduced through outcrossing resulted in desirable phenotypes with potential for new cultivar development.
Brian W. Trader, Hope A. Gruszewski, Holly L. Scoggins and Richard E. Veilleux
John Erwin, Esther Gesick, Ben Dill and Charles Rohwer
The impact of photoperiod, irradiance, and/or cool temperature on flowering and/or dormancy in Mamillopsis senilis and Echinopsis and Trichocereus hybrids was studied. Two- to 3-year-old plants (180 plants of each type) were grown for 4 months under natural daylight (DL) conditions (August–November) in a greenhouse maintained at 26 ± 2 °C. Plants were then placed in either of two greenhouses: a cool temperature house (5 ± 2 °C; DL), or a lighting treatment house (22/18 ± 1 °C day/night temperature, respectively). The lighting treatment house had eight light environments: 1) short day (SD; 8 h; 0800–1600 hr); 2) SD+25–35 μmol·m-2·s-1; 3) SD+45–50 μmol·m-2·s-1; 4) SD+85–95 μmol·m-2·s-1; 5) DL plus night interruption lighting (NI; 2200–0200 hr; 2 μmol·m-2·s-1 from incandescent lamps); 6) DL+25–35 μmol·m-2·s-1 (lighted from 0800–0200 hr); 7) DL+45–50 μmol·m-2·s-1; and 8) DL+85–95 μmol·m-2·s-1. Supplemental lighting was provided using high-pressure sodium lamps. Plants were placed in the cool temperature house for 0, 4, 8 or 12 weeks before being placed under lighting treatments. All plants received lighting treatments for 6 weeks and were then placed in a finishing greenhouse (DL; 22 ± 2 °C). Data were collected on approximate day when growth resumed, the date when each flower opened (five only), total flower number per plant, and how long each flower stayed open (five only). Whether species exhibited dormancy and what conditions, if any, broke that dormancy was identified. Species were also classified into photoperiodic, irradiance, and vernalization response groups with respect to flowering.
T.J. Gianfagna, R.H. Merritt and J.D. Willmott
Aquilegia cultivars `Songbird Bluebird', `Songbird Robin', `Dove Improved', `Colorado Violet/White' and five cultivars from new experimental genetic lines (`Red and White', `Rose and White #1', `Rose and White #2', `Scarlet and Yellow' and `White') will flower without vernalization, but little is known of their response to light or plant growth regulators. Plants were started from seed on 5 Jan. 1999 and grown in either natural light or 33% shade, and treated with gibberellins (GA4/7) at the seven-leaf stage. Flowering time, number of flowers/plant, and plant height were evaluated through 31 May 1999. All five cultivars from the new genetic lines bloomed during the study. `White', grown in shade and treated with GA4/7, bloomed 2 weeks earlier (115 days) than untreated plants grown in natural light (130 days). `Songbird Robin', treated with GA4/7, bloomed in 146 days, and was the only other cultivar to bloom. Flower numbers were greater in natural light than in 33% shade. GA4/7 increased flowering for four of five cultivars, in the new genetic lines, grown in natural light. In shade, GA4/7 increased flowering for three of five cultivars. Height response to GA4/7 was significant in both natural light and 33% shade. Four of the five cultivars in the new genetic lines were taller when treated. All five of these cultivars were taller when grown in natural light verses 33% shade. `White' and both `Rose and White' cultivars were consistently taller, bloomed earlier and were more floriferous when treated with GA4/7.
Emily A. Clough, Arthur C. Cameron, Royal D. Heins and William H. Carlson
Oenothera fruticosa L.`Youngii-Lapsley' and Stokesia laevis L'Hér. `Klaus Jelitto' are two hardy herbaceous perennials with great potential as pot crops. The vernalization and photoperiod requirements were examined for each species. Plants were cooled for 0, 3, 6, 9, 12, or 15 weeks at 5 °C with a 9-h photoperiod. After cold treatment, plants were forced in greenhouses at 20 °C under a 16-h photoperiod using high-pressure sodium lamps. The photoperiod requirement was determined by forcing plants at 20 °C with and without a 15-week cold treatment at 5 °C under 10-, 12-, 13-, 14-, 16-, 24-h and 4-h night interruption using incandescent lamps. Plants of Oenothera fruticosa `Youngii-Lapsley' cooled for 0 weeks did not flower. All plants cooled for 3 weeks flowered and time to flower decreased from 53 to 43 days as duration of cold increased from 3 to 15 weeks. `Youngii-Lapsley' flowered under every photoperiod, but time to flower and number of flowers decreased from 54 to 40 days as photoperiod increased from 10 to 24 h. Percentage flowering of Stokesia laevis `Klaus Jelitto' increased from 50 to 100, and time to flower decreased from 112 to 74 days as duration of cold increased from 0 to 6 weeks. Without a cold treatment, plants of `Klaus Jelitto' flowered only under daylengths of 12, 13, and 14 h. After cold treatment, plants flowered under every photoperiod except 24 h, and time to flower decreased from 122 to 65 days as photoperiod increased from 10 to 16 h. Additional aspects of flowering and the effect of different forcing temperatures will be discussed.
Jason Walker, John S. Caldwell and Robert H. Jones
To assess the value of uncultivated vegetation for control of cucumber beetles, populations of striped (Acalymma vittatum Fabr.), spotted (Diabrotica undecimpunctata howardi Barber), and western cucumber beetles (Acalymma trivittatum Mann.) (Coleoptera: Chrysomelidae) and natural enemy Diptera flies (as an indicator of Celatoria spp. parasitoids), Pennsylvania leatherwings (Chauliognathus pennsylvanicus DeGeer) (Coleoptera: Cantharidae), lady beetles (Coleoptera: Coccinellidae), Hymenoptera wasps, and spiders were monitored with sticky traps on 50-m transects running through a field of Cucumis sativa L. `Arkansas Littleleaf' into bordering uncultivated vegetation. Plant species composition was determined in square plots around each sticky trap by estimating total plant cover and height distribution of plants from 0 to 1.0 m. In both years, numbers of cucumber beetles increased and numbers of Diptera decreased towards the crop. These trends increased monthly to peaks in Aug. 1995 (0.3 to 6.0 striped cucumber beetles; 40.0 to 15.3 Diptera) and July in 1996 (0.1 to 7.1 striped cucumber beetles; 46.7 to 15.5 Diptera). Abundance of individual plant species contributed more to maximum R 2 regression of insect populations than did measures of plant diversity in sampling squares. Diptera were negatively correlated with sweet-vernal grass (r = –0.65 at 0 m) and wild rose (r = –0.62 at 0.5 m) in 1995, and goldenrod (r = –0.31, –0.59, and –0.53 at 0.5, 0.75, and 1.0 m, respectively) in 1996, but positively correlated with wild violets (Viola spp.) (r = +0.38 at 0 m) in 1996. Cucumber beetles were negatively correlated with wild violets (r = –0.30 at 0 m) and white clover (Trifolium repens) (r = –0.37 at 0 m) in 1996. These results suggest that increasing or decreasing specific plants in uncultivated vegetation might be useful for influencing pest and beneficial insect populations in cucurbit production.
Much of the medicinal activity induced by vegetable Alliums is derived from a suite of organosulfur compounds formed following hydrolysis of the S-alk(en)yl-l-cysteine sulfoxides (ACSOs). One of these medicinal activities is the inhibition of blood platelet aggregation; a factor that may influence cardiovascular health. Concentrations of ACSOs in the onion bulb ebb-and-fl ow during the vegetative phase, suggesting they act as storage forms of sulfur. To examine whether medicinal efficacy paralleled these changes, I tracked bulb, leaf, and inflorescence-induced antiplatelet activity during reproductive growth of four onion genotypes. Levels of bulb-induced antiplatelet activity dropped sharply for the first 8 weeks following the end of vernalization. Leaf-induced antiplatelet activity also dropped rapidly for the first 4 weeks, but rose precipitously by week 6. The rapid loss in leaf-induced antiplatelet efficacy between week 6 and week 8 suggests a recycling of these organosulfur compounds from the leaves to the developing flower stalk and inflorescence, which would be needed for protection against insect pests. Overall, I found a dramatic decrease in bulb-induced antiplatelet activity concomitant with an initially similar decrease and subsequent increase in leaf-induced antiplatelet activity. These were complemented by the presence of high levels of antiplatelet activity induced by the inflorescence. These data indicate development mediates the medicinal activity induced by onion plants. Furthermore, the flux of antiplatelet activity induced by various plant organs suggests that this medicinal trait is serendipitously associated with the storage and cycling of sulfur in onion plants; perhaps in response to insect predation.
J. Ryan Stewart, William R. Graves and Reid D. Landes
Can Carolina buckthorn (Rhamnuscaroliniana) persist north of its native habitat without becoming invasive? Its distribution (USDA zones 5b to 9b) suggests that genotypes vary in cold hardiness, and invasiveness of other Rhamnus sp. has been linked to unusually early budbreak each spring. Therefore, we investigated depth of cold hardiness and vernal budbreak of Carolina buckthorns from multiple provenances and made comparisons to the invasive common buckthorn (Rhamnus cathartica). Budbreak was recorded in Ames, Iowa, from 9 Apr. to 10 May 2002. Buds of common buckthorn broke earlier than those of Carolina buckthorn, and mulching plants of Carolina buckthorn hastened budbreak. Stem samples were collected in October, January, and April from a plot in Ames, Iowa (USDA zone 5a), of Carolina buckthorns from three provenances (Missouri, Ohio, and Texas) and of naturalized common buckthorns. A similar schedule was followed during the next winter, when two plot locations [Ames, Iowa, and New Franklin, Mo. (USDA zone 5b)], were compared, but Carolina buckthorns from only Missouri and Texas were sampled. Carolina buckthorn and common buckthorn survived midwinter temperatures as low as –21 °C and –24 °C, respectively. Provenance differences were minimal; Carolina buckthorns from Missouri were more hardy than those from Ohio and Texas only in April of the first winter. We conclude that its cold hardiness will permit use of Carolina buckthorn beyond where it is distributed in the southeastern United States. Delayed budbreak of Carolina buckthorn relative to that of common buckthorn may underscore the potential for Carolina buckthorn in regions with harsh winters and may lessen its potential to be as invasive as common buckthorn.
Chen-Yu Lin, Kan-Shu Chen, Hsuan-Ping Chen, Hsiang-I Lee and Ching-Hsiang Hsieh
and an inflorescence meristem that continuously generates replicas ( Smyth, 1995 ). Many Brassica species have chilling requirements and flowering induced by vernalization. After vernalization, cauliflower will exhibit normal curd development under
Rebecca Grube Sideman, Amanda Brown, Ruth Hazzard and Heather Bryant
by vernalization or prolonged exposure to cool temperatures once the onion plant has reached a critical size ( Pike, 1986 ; Streck, 2012 ). This critical plant size varies with cultivar, ranging from 7 to 10 or more true leaves ( Brewster 2008
Kaoru Nakamura, Hirotoshi Hino, Sadao Gunji, Norio Hattanda, Toshio Murata, Hiroshi Tominaga, Koichi Fukumoto and Ryo Akashi
, and summer ( Inoue, 2002 ). In Japan, most growers grow cultivars of the winter and spring flowering types because cultivars of both types require cold storage of germinated seed for vernalization to induce flowering from November. Cultivars of the