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  • Author or Editor: Tim D. Davis x
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Plugs of Zinnia elegans Jacq. `California Giant' and Tagetes erecta L. `Golden Climax' and `Grange Lady' were treated with foliar sprays of uniconazole solutions at 0, 5, 25, or 50 mg·liter-1 (spray volume = 120 ml·m-2). Ten days later individual plants were transplanted to OS-liter pots for evaluation of subsequent growth and flowering. All uniconazole treatments reduced height 10 days after application; the extent of reduction depended on uniconazole spray concentration. With zinnia, only the 50-mg·liter-1 foliar spray caused undesirable stunting for at least 1 month after transplanting. None of the uniconazole treatments affected time to anthesis for zinnia. With both marigold cultivars, all uniconazole treatments reduced growth the 2 weeks following transplanting. The highest concentration reduced marigold shoot growth during this period to 25% to 30% of untreated controls. Between 2 and 4 weeks after transplanting growth of all uniconazole-treated marigolds recovered to levels similar to the control. Time to anthesis was increased by the 50 mg·liter-1 treatment for both marigold cultivars. These results suggest that foliar sprays of uniconazole at 5 to 25 mg·liter-1 can control plug height during production without adversely affecting subsequent growth and flowering. with both zinnia and marigold, a single GA3 foliar spray of 100 mg·liter-1 at transplanting partially reversed the adverse post-production effects of the 50 mg·liter-1 uniconazole foliar spray.

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Indonesia is one of the most populated countries in the world and is rich in plant biodiversity. The country’s hot humid climate is conducive to the production of many tropical horticultural crops. There are many plant species indigenous to Indonesia that have potential as horticultural crops but which have not been fully evaluated and therefore remain underused. Many of these plants have market potential and may have value for human health and nutrition. Furthermore, horticulture has been identified as one of the priority areas for collaboration between U.S. and Indonesian universities and for Indonesian agricultural development. Accordingly, we are presently working with three Indonesian universities to facilitate agricultural development related to horticulture by: 1) strengthening their curriculum related to plant biodiversity; 2) conducting research aimed at identifying bioactive compounds in underused plants that may have benefit to human health; 3) establishing university-led outreach education programs that lead to a better understanding of plant biodiversity and use; and 4) fostering enterprise based on underused Indonesian plant species. Other untapped agricultural research and development opportunities exist in the postharvest handling of tropical fruits and vegetables. Overall, the climate for collaboration between U.S. and Indonesian academic institutions is quite favorable from both a political and a scientific perspective.

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Seeds of four lupine species (L. microcarpus var. aureus, L. havardii, L. succulentis, and L. texensis) were subjected to 0, –2, –4, –6, or –8 bars osmotic potential using PEG 8000 solutions. Seeds of all species were acid scarified prior to placement in petri dishes containing the osmotic solutions. Petri dishes were placed in a seed germination chamber at 25°C with germination data collected daily for 15 days. Seeds of L. havardii, a desert species native to west Texas exhibited the greatest germination as osmotic potential declined while L. succulentis, a species adapted to moist sites, exhibited the greatest decline in germination as osmotic potential decreased. The other species exhibited intermediate germinability under the lower osmotic potentials.

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The Big Bend bluebonnet, Lupinus havardii Wats., is a showy winter annual native to a narrow geographical range in southwestern Texas with blue, fragrant 0.5–1.0-m-long racemes. The L. havardii raceme has considerable potential in the floral industry, because there is a need for high-quality, durable, raceme-type cut flowers. We began a research and breeding project in 1991 aimed at evaluating the potential for this species as a specialty cut flower. Breeding strategies included the development of selfed populations as well as random pollinations among selected individuals with the aim of improving flower color, uniformity, yield, and postharvest performance. Recurrent phenotypic selection has resulted in the development of blue, pink, and white color lines. Concurrently with the breeding efforts, research on seed germination, greenhouse culture for year-round production, postharvest handling, and shipping requirements have been conducted. Trials have indicated that L. havardii is adaptable to greenhouse culture and that individual plants can produce 15–25 marketable racemes within 4–5 months from sowing. Two years of commercial greenhouse trials have been completed. Blue and white cultivars will be released by Texas A&M Univ. within the next year.

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Abstract

Storage of Rhododendron catawbiense Michx. ‘Roseum Elegans’ cuttings in moist burlap bags at 21° or 2°C for 21 days did not consistently reduce the percentage of rooting or rootball size. During storage, leaf water potential (ψw) of the cuttings increased from −0.47 MPa initially to −0.27 MPa after 14 days, regardless of storage temperature. Carbohydrate concentrations in the bases of the cuttings changed with time and storage temperature, but apparently neither these changes nor changes in ψw were large enough to influence subsequent rooting.

Open Access

Abstract

CO2 enrichment (1200 μl CO2/liter of air) during rooting increased the number of roots per cutting from 7.4 to 12.0 in Peperomia glabella A. Dietr. ‘Variegata’. CO2 enrichment increased length and dry weight of root systems and fresh and dry weights of whole cuttings in P. glabella, Fuchsia magellanica Lam., Peperomia nivalis Miq., Hemigraphis alternata T. Anderson, and Begonia × argenteo-guttata V. Lemoine but not in Osmanthus heterophyllus P.S. Green ‘Rotundifolius’, Ficus pumila L., and Pelargonium × hortorum L.H. Bailey ‘Sprinter Scarlet’. After 4 weeks of growth at 330 μl CO2/liter, only P. nivalis retained the size differential due to CO2 enrichment.

Open Access

Seeds of moth bean (Vigna aconitifolia Jacqu. Marechal cv. Jaadia) were germinated in the presence of 0, 0.1, 1, or 2 μm 24-epibrassinolide (EBL). After 72 h, cotyledons were excised and the seedlings exposed to 22 or 48 °C for 90 min. At 48 °C EBL increased total electrolyte, K+, and sugar leakage relative to the untreated control. Following exposure to 48 °C, EBL-treated seedlings had higher malondialdehyde concentrations than controls indicating that EBL enhanced high temperature-induced lipid peroxidation. At 48 °C, EBL increased ascorbic acid oxidase activity and decreased superoxide dismutase activity relative to the control. Taken together, these data do not support the hypothesis that brassinosteroids confer thermotolerance to plants. On the contrary, EBL increased high temperature-induced damage and reduced the activity of some antioxidant systems that may protect against stress-induced cellular damage.

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Moth bean (Vigna aconitifolia Jacqu. Marecbal cv. Jaadia) seeds were germinated in 0, 0.1, 1, or 2 μm EBL. After 72 hours, seedlings were exposed to 22 or 48C for 90 minutes. At 48C, EBL increased total electrolyte, K+, and sugar leakage from the seedlings relative to the control. Following exposure to 48C, EBGtreated seedlings bad higher malondialdebyde concentrations than controls, indicating that EBL enhanced high-temperature-induced lipid peroxidation. At 48C, EBL increased ascorbic acid oxidase activity but decreased superoxide dismutase activity relative to the control. Taken collectively, these data do not support a hypothesis that brassinosteroids confer beat shock tolerance to moth bean. Chemical name used: 24-epibrassinolide (EBL).

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`German Red' is a thermotolerant cultivar of carnation (Dianthus caryophyllus) that blooms almost year-round in Texas. This study was initiated to evaluate the feasibility of inducing somatic embryos for use in gene transfer Studies and rapid mass propagation. Internodal explants, obtained from microshoots of plantlets cultured on MS medium containing 5 μM benzyladenine (BA) and 0.5 μM naphthaleneacetic acid (NAA), were used to initiate callus. Callus formation was induced on MS medium containing 3% sucrose, 0.1% casein hydrolysate and 2,4-D (1-5 μM) alone or in combination with BA (2 or 4 μM) or kinetin (2 or 4 μM). After about 5 weeks, the callus was transferred to either semisolid or liquid MS basal medium with or without kinetin and BA. Within 20-30 days, pro-embryogenic callus masses were observed. The embryos developed from white embryonic tissue and exhibited typical stages of embryogenesis. After 5 weeks, up to 70% of the cultures grown in the liquid medium with or without BA exhibited a profusion of embryo-like structures. Because only a small percentage of these developed into plantlets, more work is needed to enhance conversion frequency.

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