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Kimberly A. Pickens, (Max) Z.-M. Cheng and Stephen A. Kania

The mitotic inhibitors, colchicine and oryzalin, were evaluated for their effects on callus, adventitious shoot formation, and tetraploid induction of Euphorbia pulchurrima `Winter Rose'. In vitro grown leaf sections were placed on various media supplemented with either colchicine or oryzalin at various concentrations for 1 to 4 days. Colchicine was less damaging to leaf tissues than oryzalin. On various colchicine-containing media, prolific calluses were produced and adventitious shoot formation was observed. Regenerated shoots were found to be diploid as determined by flow cytometry. On media supplemented with oryzalin (28.9 μm to 144 μm), leaf tissues produced callus but failed to form adventitious shoots. Samples of calluses produced on oryzalin-containing media were subject to analysis using flow cytometry and were found to be diploid. These results suggest that the colchicine is less toxic on poinsettia tissues and shoot induction than oryzalin. Additional experiments are needed to establish a protocol for in vitro induction of poinsettia tetraploid with colchicine and oryzalin.

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Ryan N. Contreras, John M. Ruter and Brian M. Schwartz

to induce polyploidy have used colchicine. Colchicine acts by disrupting the microtubular structure of dividing cells in both plants and animals ( Bartels and Hilton, 1973 ). The mode of action of dinitroaniline herbicides such as oryzalin has also

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Bruce L. Dunn and Jon T. Lindstrom

equalizing chromosome numbers by mitotic polyploidization can be achieved by using mitotic inhibitors. The most commonly used chemical mutagens in horticulture are colchicine and oryzalin. Using colchicine, Rose et al. (2000) produced a tetraploid B

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Ryan N. Contreras, John M. Ruter and Wayne W. Hanna

(Premier Tech, Quakertown, PA). Trays were placed in a glasshouse with natural daylength and set day/night temperatures of 27/20 °C. One-day shoot tip treatment with oryzalin. Seeds were pretreated by soaking in water and surfactant, and were then

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Hamidou F. Sakhanokho, Kanniah Rajasekaran, Rowena Y. Kelley and Nurul Islam-Faridi

colchicine and oryzalin ( Dhooghe et al., 2009 ; Pickens et al., 2006 ; Rey et al., 2002 ). Colchicine binds poorly to plant tubulins but has a high affinity for animal microtubulins and thus is toxic to humans ( Morejohn et al., 1987 ). By contrast

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Glendon D. Ascough, Johannes van Staden and John E. Erwin

) of colchicine induced microtubule polymerization to form new structures in c-metaphase cells. These new structures are thought to aid reconstitution of polyploid nuclei and subsequent re-entry into the cell cycle ( Caperta et al., 2006 ). Oryzalin and

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Amit J. Jhala, Analiza H.M. Ramirez and Megh Singh

) and oryzalin (Surflan®; United Phosphorus, King of Prussia, PA) are commonly used soil-applied herbicides for control of many annual weeds and certain broadleaf weeds in citrus. Rimsulfuron (Solida™; Cheminova, Research Triangle Park, NC) is a

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Luke T. Case and Hannah M. Mathers

Herbicide-treated mulches can increase duration of efficacy; however, it is not known if the herbicide-treated mulches can reduce the amount of herbicide getting into the root zone or leachate water. The objective of this study is to examine herbicide movement and leaching potential using a bioassay between pine nuggets sprayed with oryzalin vs. a direct spray of oryzalin. Oryzalin-treated mulch and direct sprays were applied to 1-gallon pots at 2.0 lbs/acre a.i. (2.2 kg·ha-1 a.i.). The study was repeated in time, with trial 1 starting in Jan. 2004, and trial 2 starting in Nov. 2004. Both were conducted in a glass greenhouse in Columbus, Ohio. There were six dates of evaluation in each study: 0, 4, 8, 16, 32, and 64 DAT. An oat (Avenasativa) bioassay was conducted on three pot levels (0–2, 2–8, and 8–15 cm) and leachate to determine herbicide presence on each evaluation date. In trial 1, pots with direct sprays showed more herbicide presence in the top 2 cm than the oryzalin-treated mulch pots on each of the evaluation dates. In trial 2, results were much the same except for 32 DAT, where the oryzalin-treated mulch showed slightly more presence than the spray treatment at the 0-2 cm level. In both trials, there was a significant increase in herbicide presence in the oryzalin-treated pine nugget pots at the 0–2 cm level from 0 to 4 DAT, suggesting that the mulch does retain the herbicide. Also, results indicated more herbicide leaching into the 2–8 cm zone with the direct sprays compared to the pots containing oryzalin-treated pine nuggets. In trial 2, there was indication of the herbicide getting into the 8–15 cm zone from the direct spray treatment up to 8 DAT. There were no signs of herbicide presence in the leachates from any of the treatments.

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Justin A. Schulze and Ryan N. Contreras

indica ( Ye et al., 2010 ), Platanus acerifolia ( Liu et al., 2007 ), Pyrus pyrifolia ( Kadota and Niimi, 2002 ), and Ziziphus jujuba ( Gu et al., 2005 ). Oryzalin is another effective mitotic inhibitor for chromosome doubling in many woody plants

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Yayan Feng, Leifeng Xu, Panpan Yang, Hua Xu, Yuwei Cao, Yuchao Tang, Suxia Yuan and Jun Ming

undesirable mutagenic effects on plants ( Borisy and Taylor, 1967 ; Cohen and Yao, 1996 ; Liu et al., 2007 ). Oryzalin is considered a preferable alternative to colchicine because of its lower toxicity and lower required dosage ( Bouvier et al., 1994