True-breeding lines of Zinnia marylandica Spooner, Stimart & Boyle [allotetraploids of Z. angustifolia H.B.K. and Z. violacea Cav. (2n = 4x = 46)] were backcrossed with autotetraploid Z. angustifolia (2n = 4x = 44) and Z. violacea (2n = 4x = 48). Seed-generated, backcross (BC1) families were screened for resistance to alternaria blight (Alternaria zinniae Pape), bacterial leaf and flower spot [Xanthomonas campestris pv. zinniae (Hopkins and Dowson) Dye], and powdery mildew (Erysiphe cichoracearum DC. ex Merat). All BC1 families exhibited high levels of resistance to alternaria blight and powdery mildew. BC1 families derived from crossing Z. marylandica with autotetraploid Z. angustifolia were highly resistant to bacterial leaf and flower spot, whereas BC1 families derived from crossing Z. marylandica with autotetraploid Z. violacea were susceptible to this disease. Our results suggest that one Z. angustifolia genome in BC1 allotetraploids is sufficient to confer resistance to A. zinniae and E. cichoracearum, but at least two Z. angustifolia genomes are required in BC1 allotetraploids to provide resistance to X. campestris pv. zinniae.
Thomas H. Boyle and Robert L. Wick
Genhua Niu, Minzi Wang, Denise Rodriguez, and Donglin Zhang
or even seasonally in landscapes. Zinnia marylandica is a hybrid between Z. angustifolia and Z. violacea with bright colors and prolific bloom and is resistant to disease, heat, and drought stresses ( Spooner et al., 1991 ). Z. maritima
Lesley A. Judd, Brian E. Jackson, and William C. Fonteno
25 June 2014, 60 rhizometers were filled with a 3 peat:1 perlite:1 vermiculite (by volume) substrate, which had an initial pH value of 5.8. Zinnia ( Zinnia marylandica ‘Zahara Cherry’; 288-tray; C. Raker & Sons, Inc.) plugs were planted in 40
John E. Montoya Jr., Michael A. Arnold, Juliana Rangel, Larry R. Stein, and Marco A. Palma
), zinnias ( Zinnia ×marylandica ), and basil ( Ocimum basilicum ) ( Arnold, 2008 ). Cucumber is highly dependent on pollinators for fruit set ( University of Georgia Honey Bee Program, 2019 ). Increased visitation of pollinators has been shown to increase
Brian Dintelmann, David Trinklein, and Kevin Bradley
’ french marigold ( Tagetes patula ), ‘Prelude’ wax begonia ( Begonia × semperflorens-cultorum ), ‘Titan’ madagascar periwinkle ( Catharanthus roseus ), ‘Double Zahara’ zinnia ( Zinnia marylandica ), and ‘Wizard’ coleus ( Solenostemon scutellarioides
Thomas H. Boyle
True-breeding lines of Zinnia marylandica Spooner, Stimart and Boyle [allotetraploids of Z. angustifolia H.B.K. and Z. violacea Cav. (2n = 46)] were reciprocally backcrossed with diploid and autotetraploid forms of Z. angustifolia (2n =22 or 44) and Z. violacea (2n =24 or 48). In most cases, backcrosses were more successful with Z. angustifolia and Z. violacea as autotetraploids than as diploids. Seed-generated, backcross (BC1) families were obtained by crossing Z. marylandica (as female) with autotetraploid Z. angustifolia or autotetraploid Z. violacea. BC1 plants were phenotypically intermediate between the two parental lines for most morphological characters. Crosses between Z. marylandica and autotetraploid Z. angustifolia yielded BC1 plants with 33% stainable pollen, whereas crosses between Z. marylandica and autotetraploid Z. violacea yielded BC1 plants that produced malformed, poorly-stained pollen. No embryos were observed in capitula collected from field-grown BC1 plants. BC1 hybrids of Z. marylandica and autotetraploid Z. violacea produced larger capitula and more ray florets than Z. marylandica, and exhibited novel combinations of floral pigments not observed in Z. marylandica ray florets. BC1 hybrids of Z. marylandica and Z. violacea have commercial potential as seed-propagated, bedding plants.
Frank Balestri and William R. Graves
The genus Nyssa L. includes several woody species with traits valued by horticulturists, but only black gum (Nyssa sylvatica Marsh.) is prevalent in the nursery trade. A congener, swamp tupelo (Nyssa biflora Walt.), might be a marketable shade tree, but little is known about propagating it from seeds. Because cold, moist stratification overcomes embryo dormancies of black gum, we compared germination of cleaned seeds (surrounding pulp of fruits removed) of swamp tupelo and black gum that were stratified at 5 °C for 0, 14, 28, 42, 56, 70, 84, and 112 days. Seeds of swamp tupelo within intact drupes were also stratified. Across all durations of stratification, 79% of cleaned seeds of swamp tupelo germinated, whereas 11% of seeds within drupes germinated. Germination value of cleaned seeds of swamp tupelo increased from 1.26 to 3.23 as duration of stratification increased. Although cleaned seeds of black gum responded similarly, the benefit of stratification was more pronounced, and the mean germination percentage was lower than for swamp tupelo (66% vs. 79%). In a second experiment, irrigation with low and high concentrations of an extract of fruit pulp of swamp tupelo reduced germination of seeds of basil (Ocimum basilicum L. ‘Superbo’), spinach (Spinacea oleracea L. ‘Bloomsdale’), zinnia (Zinnia ×marylandica Spooner, Stimart, and Boyle ‘Double Zahara Cherry’), and swamp tupelo by 25% to 63% (low concentration) and 40% to 70% (high concentration). Propagators should remove the surrounding pulp from seeds of swamp tupelo and cold stratify them at least for 4 weeks.
Shasha Wu, Youping Sun, Genhua Niu, James Altland, and Raul Cabrera
of stress or injury ( Niu and Rodriguez, 2006 ). Seven cultivars of Zinnia marylandica all died when irrigated with EC at 6.0 and 8.2 dS·m −1 for 4 weeks ( Niu et al., 2012b ). Xeriscaping with native plants is promoted to conserve water
Nichole F. Edelman and Michelle L. Jones
for evaluation ( Table 1 ). Plants included wild species and cultivated varieties. Zinnia marylandica ‘Double Zahara Fire’ (not a member of the family Solanaceae) was included as a negative control, because this plant was known to have little to no
Youping Sun, Genhua Niu, and Christina Perez
’ verbena also had lower leaf Na concentrations than Zinnia marylandica and Zinnia maritime plants (zinnia) ( Niu et al., 2012b ) and C. plumbaginoides , D. cooperi , G. rigen , and T. chamaedrys ( Niu and Rodriguez, 2006a ). Leaf Na concentration