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Ali O. Sari, Mario R. Morales, and James E. Simon

Low and erratic seed germination presents a major production problem in the medicinal plants that collectively are called echinacea or purple coneflower (Echinacea angustifolia and E. pallida). In this study, nine seed lots of each E. pallida and E. angustifolia from a wide variety of commercial sources and germplasm collections were collected and treated with a solution of 1.0 mm [144.5 mg·L-1 (ppm)] ethephon (2-chloroethylphosphoric acid) to determine whether ethephon would sufficiently improve seed germination to be used by industry to improve the quality of echinacea seed. Applicationof ethephon increased seed germination in both E. pallida and E. angustifolia seed lots regardless of seed sources. The increase in germination by ethephon in eight seed lots of E. pallida and four seed lots in E. angustifolia were statistically significant compared to the nontreated control seeds. The increases in germination were also significant across seed lots for both species. Average germination increases across all seed lots were 1271 and 29% for E. pallida and E. angustifolia, respectively. Average germination of ethephon treated-untreated control seed lots was 76% to 27% and 79% to 62% for E. pallida and E. angustifolia, respectively.

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Ann Fagan Hruska, Michael A. Dirr, and F. A. Pokorny

Abstract

Fruit pulp extracts of Liriope muscari (Decne.) Bailey were analyzed chromatographically and spectrophotometrically to determine which compounds were responsible for their blue-black color. A trihydroxy series of mon-oglycosylated anthocyanidins (delphinidin, petunidin, malvidin) were isolated. The malvidin glycoside appeared to be involved in a co-pigment complex with at least a flavone, explaining the neutral pH-stable blue color. Previous work indicated that a water-soluble seed germination inhibitor was present in the pulp. Nine bands were collected as fractions from Sephadex column chromatography. Each fraction was monitored by paper chromatography before use in a bioassay that tested for germination inhibitors. Several fractions significantly inhibited seed germination of Cucumis sativus L. ‘Poinsett’. Four classes of phenolic compounds were identified from the chromatograms: anthocyanins, anthoxanthins, phenolic acids, and a tannin-like polyphenol. Phenolic acids and the tannin-like substance were most prevalent in the 3 most toxic fractions. A mixture of these 3 fractions caused seed germination inhibition exceeding that attained by the individual fractions. Caffeic acid was tentatively identified as one of the phenolic acids present. Results indicated that germination inhibition is due to the combined action of several phenolic compounds.

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Fredy R. Romero, Kathleen Delate, and David J. Hannapel

With the increase in popularity of echinacea as a botanical supplement, organic production of this herb continues to grow. Echinacea seeds typically show a high percentage of dormancy that can be broken by ethephon or gibberellic acid, but these methods are not accepted in organic production. We examined in three experiments the effects of varying seed source and germination conditions on echinacea growth. To determine the efficacy of nonchemical treatments, we evaluated the effect of light with and without cold-moist stratification on seed germination of the three most important medicinal species of echinacea, E. angustifolia, E. purpurea, and E. pallida. We used cold-moist stratification under 24 h light, 24 h dark, and 16/8 h (light/dark) to break seed dormancy. We found that germination was enhanced in seeds from a commercial organic seed source, compared to a public germoplasm source. When seeds were not cold-moist stratified, light increased germination in E. angustifolia only, suggesting differential dormancy among the three species. We found that when seeds were cold-moist stratified under 16–24 h of light for 4 weeks, the percentage and rate of germination increased 10% over the control, suggesting this method as an alternative to chemical seed treatments.

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Linda L. Knowlton and K. C. Sink Jr.

Abstract

Three sets of Petunia hybrida Vilm. lines were used with each set comprised of the 3 genotypes, multiflora (gg), grandiflora (GG), and heterozygote (Gg). Seed germination was consistently high for the hybrid Gg (92%), intermediate for gg (77%) and low for GG (45%). The fresh and dry wt of 28-day-old seedlings was inconsistent but the Gg hybrid was the most vigorous at 49 days followed by the gg and GG genotypes. No differences were observed in N, P, K, Na, Mn, Fe, Cu, Zn, or Al in vegetative leaves of the 3 genotypes. Differences in Ca, Mg, and B occurred, but they were not uniform with respect to genotype or to genotypes within a set. Calcium and Mg were generally highest in gg and lowest in GG. Boron in 1 of 2 experiments showed the same pattern. The physiological roles of the observed differences in elemental composition with respect to chlorophyll composition, sugar metabolism, and vigor as indicated by an increase in fresh and dry wt, in the 3 genotypes are discussed.

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Hae-Jeen Bang, Soo-Jung Hwang, Hyun-Sook Ham, and Jung-Myung Lee

Dry heat treatment has been commonly used to inactivate some seed-borne pathogens in vegetable seeds. Virtually all the gourd seeds for watermelon rootstock are being treated with dry heat to inactivate cucumber green mottle mosaic virus (CGMMV, a strain of tobamovirus) and Fusarium. Seeds of five gourd and one squash cultivars were treated with dry heat (35 °C for 24 h + 50 °C for 24 h + 75 °C for 72 h) and, immediately after the dry heat treatment, the seeds (moisture content of 1% or lower) were allowed to absorb atmospheric moisture in a moisture saturated chamber until the seed moisture contents reached 2% to 8%. After the equilibrium obtained, the seeds were sealed in air-tight bags and stored for 1 day or 30 days at 20 °C. The seeds were then sown in cell trays and the emergence and seedling characteristics were evaluated. Dry heat treatment caused significant delay in emergence in all tested cultivars, but had little or no influence on the final emergence rate. Moderate to severe injury was observed in seedlings grown from dry heat-treated seeds in three out of six cultivars tested. However, little or no dry heat phytotoxicity was observed in other cultivars, thus suggesting the marked differences in cultivar susceptibility to dry heat treatment. Rapid humidification before sealing also appeared to reduce the early emergence rate in some cultivars, but had no effect on the final emergence rate in most cultivars. Storage of dry heat-treated seeds in sealed bags for 30 days before sowing was highly effective in minimizing the phytotoxicity symptoms in seedlings as compared to the seedlings grown from the seeds sown immediately after the dry heat treatment. This suggests that the reestablishment of metabolic process required for normal seed germination requires a long period after the dry heat treatment. Other characteristics associated with DH treatment will also be presented.

Open access

Kai Jia, Cunyao Yan, Huizhuan Yan, and Jie Gao

local seed retailers. ‘Qiamagu’ was found to be a salt-tolerant turnip cultivar by Shi et al. (2011) . Plant growth and treatments Expt. 1: Salt stress on seed germination. Seeds of turnips were sterilized using sodium hypochlorite (5%) for 15 min and

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Meiling Yang, Fang Li, Hong Long, Weiwei Yu, Xiuna Yan, Bin Liu, Yunxiu Zhang, Guorong Yan, and Wenqin Song

., 2008 ). The exact pollen germination percentage in different populations of M. sieversii remains unclear. Seed germination is another major aspect for plant reproduction. Relieving seed dormancy successfully is critical for fruit breeding. Evidence

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Jacob S. Bravo, Thomas Okada Green, James R. Crum, John N. Rogers III, Sasha Kravchenko, and Charles A. Silcox

previous research with dazomet was conducted based on the product’s initial label, which was focused more on production agriculture fields. The goal of current research is to optimize weed seed germination control when dazomet is used as per the current

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Jonas Christensen, Uffe Bjerre Lauridsen, Christian Andreasen, and Henrik Lütken

potential to introduce the species as a crop in agriculture by an organic approach and on other soil types than it normally thrives. We focused on seed germination ability, growth rate, and biomass production at low fertilizer levels. Most vegetable crops

Open access

Melike Cirak and James R. Myers

of seed germination without fungicide treatment for green ( p pc ), white ( p Pc ) and colored-seeded ( P Pc ) snap bean genotypes grown at the Oregon State University Vegetable Research Farm, Corvallis, OR, in 2018. p , plant parts not pigmented