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Electric lamps have been used to grow plants for nearly 150 years with some of the earliest references being the work of Mangon (1861) and Prilleux (1869) (cited in Pfeiffer, 1926 ). As might be imagined, plant lighting technologies closely

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With the cooperation of six commercial greenhouses (five in Colorado, one out of state), rooted poinsettia cuttings and bedding plant plugs were collected and analyzed for Pythium and Rhizoctonia, two common root rotting pathogens in Colorado greenhouses. Samples of plant, soil, and water debris were taken from four greenhouses, as well as samples of growing media ready for use. These were also analyzed for Pythium and Rhizoctonia. Fungi recovered from the plant, debris, or growing media samples were identified, grown in pure culture, and introduced into susceptible plants (Vinca minor) in pathogenicity studies. Neither pathogen was isolated from the rooted poinsettia cuttings tested. Pythium was not found in any of the plug material or in growing media. Rhizoctonia solani was found in 16% of the plug samples and 7% of the growing media samples tested. Debris from greenhouse floors yielded four species of Pythium as well as Rhizoctonia solani. Isolates of each fungus were able to colonize, but not adversely affect, inoculated plants in pathogenicity studies. It appears that disease causing organisms that have potential to decrease plant quality and growth are already present in the greenhouse. Control of root rotting pathogens can best be carried out by relying heavily on sanitation measures.

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Money plant may be a valuable plant to cultivate as an ornamental plant in China. Money plants are grown for the translucent, silvery, rotund, pseudo-septa that stay on flower stalks and are all that remain of ripened seed pods after the two outer coverings drop with the seeds. Money plant was first introduced from Canada into China in 1993. Seed germination and seedling development were successful. There were 18 to 34 leaves per plant and average plant height was 30 cm by the end of Nov. 1993. Plants exposed to environmental conditions (ENV) became dormant at low temperature. Plants grown under greenhouse conditions (GH) continued to grow until May. ENV plants escaped dormancy between April and May, grew normally, blossomed, and bore pods with seeds. GH plants blossomed; however, most of the blossoms dropped off and seed pods failed to develop. Flower stalks with many lateral inflorescences grew from ENV plant shoot apexes. In some cases, secondary and tertiary branches developed into the secondary and tertiary lateral inflorescences. There were ≈30 flowers per inflorescence and 30% of flowers were developed successfully into pods that usually contained five to six seeds with a maximum of nine seeds per pod. These results indicate that money plant may be successfully cultivated in Shandong, China.

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We developed an Agrobacterium-mediated leaf disk transformation method for chrysanthemum. We introduced a chimeric chalcone synthase (CHS) gene isolated from chrysanthemum into cv. Moneymaker (pink type) to produce white-flowered plants. The CHS coding sequence was in antisense or sense orientation relative to the CaMV 35S promoter. 3.6% (3/83) antisense-transformed plants and 1.5% (2/133) sense-transformed plants produced completely white flowers. Pigment analysis revealed that this was due to a block at CHS. To study stability of color change of the white Moneymaker plants. Moneymaker, a Moneymaker regenerant, an antisense white (2706),and a sense white (31435) were compared. There was no difference between Moneymaker and the regenerant. Both 2706 and 31435 were vegetatively propagated with good stability; all plants produced white or very pale pink flowers. 2706 flowered 7 days late and 31435 10-12 days late. Flower number was similar for all four lines tested.

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tolerance to thrips feeding, rather than host plant resistance to insect infestation, can be a very important resistance mechanism involved in reducing damage to onion crops. A wide range in tolerance to thrips feeding injury was demonstrated independent of

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203 COLLOQUIUM 4 (Abstr.450–455) Intellectual Property Rights: Protection of Plant Materials

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vary with chlorosis of leaves being common followed by asymmetrical wilting for the plant. When infection takes place in seedlings, noticeable stunting of the plant occurs followed by chlorosis and death. Necrosis of the stem, in the form of brown

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