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S.D. Reid, M. Ali-Ahmad, and H.G. Hughes

The use of random amplified polymorphic DNA (RAPD) markers has been shown to be a potentially useful technique for identifying buffalograss breeding lines. Analysis of RAPD markers has also revealed considerable variation within, as well as among, each of four natural buffalograss populations surveyed. Identification of genetic markers for quantitative traits, such as physiological components of tolerance to salt stress, can provide important information for plant improvement programs. The objectives of this study were to develop DNA fingerprints for buffalograss clones selected from an in vitro seedling screening program for survival at high NaCI (200–250 mM) levels, identify markers for future analysis, and assess the variability among the lines. DNA was extracted from leaves of 10 salt-selected and 15 non-selected buffalograss clones. Fifty-two 10-mer primers were screened for ability to produce bands with DNA from four clones as visualized on ethidium-stained agarose gels. Bands were most reproducible with a genomic template DNA concentration of 1 ngμl–1 reaction volume. Primers selected for ability to produce a moderate number of clear bands were used to produce RAPD profiles of the 25 clones. Abundant polymorphism to distinguish among clones was found. Four primers produced a total of 45 polymorphic markers. The primer 5′-CGGAGAGCCC-3′ produced 11 readily scored markers, allowing identification in 94.67% of pair-wise comparisons. As a group, RAPD profiles of salt-selected clones are more variable than non-selected clones from the same population; however, no unique pattern of markers generated by primers screened to date differentiates all salt-selected clones from the non-selected group.

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Susan S. Han, Abraham H. Halevy, Roy M. Sachs, and Michael S. Reid

Exposure of dormant corms of Triteleia laxa `Queen Fabiola' to 20 ppm C2H4 for 7 days promoted flowering of small corms and resulted in increased apical meristem size, early sprouting, early flowering, more flowers per Inflorescence, and increased fresh weight of daughter corms and cormels. The respiration rate of the C&treated corms increased to four to five times that of the controls during the 7-day treatment, declined markedly after termination of the C2H4 treatment, but remained higher than that of the controls. The C2H4 effects were associated with increased growth rate and consequently a greater final size of the apical meristem (determined by scanning electron microscopy). Leaves produced by C2H4-treated corms were wider, longer, and weighed more than those of the controls.

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Susan S. Han, Abraham H. Halevy, Roy M. Sachs, and Michael S. Reid

Flowering of brodiaea (Triteleia laxa syn. Brodiaea laxa `Queen Fabiola') did not have an obligate requirement for manipulation of temperature or photoperiod. Vernalization of corms reduced the greenhouse forcing phase but did not alter the number of flowers per inflorescence or scape length. Long photoperiods hastened flowering but decreased flower quality and flowering percentage. Scape length, which was not affected by photoperiod or mother corm size, was increased when plants were grown at night temperatures < 10C. Diameter of the apical meristem in the dormant corm, flowering percentage, and flower quality were not affected by a 10-fold increase in corm size above a critical weight (0.6 g). In contrast, the weight and number of daughter corms were closely correlated with mother corm size. The optimum planting depth for brodiaea corms was 10 cm below the soil surface.

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Philip E. Hammer, S.F. Yang, M.S. Reid, and J.J. Marois

The effectiveness of fungistatic atmospheres for postharvest control of Botrytis cinerea Pers. infections on cut rose flowers (Rosa hybrids L.) was investigated. Storing cut `Sonia', `Royalty', and `Gold Rush' roses at 2.5C with 10% CO2 for 5 days, followed by 2 days of cold storage in air, reduced the number of B. cinerea lesions that developed on inoculated and noninoculated flower petals by 77% and 82%, respectively, compared to cold storage for 7 days in air. Higher CO2 concentrations and longer CO2 treatment times reduced disease severity further, but resulted in unacceptable leaf discoloration on some cultivars. No deleterious effects of CO2-enriched storage atmospheres on flower quality, weight gain, or vase life were observed. Storage at 2.5C for 7 days in 2 μl SO2/liter reduced B. cinerea infections on inoculated and noninoculated flowers by 53% and 43%, respectively. No deleterious effects on flower quality, weight gain, or vase life were observed. Higher SO2 levels reduced disease severity further, but caused bleaching of the petal margins and necrosis around leaf wounds.

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T.E. Thompson, L.J. Grauke, William Reid, M.W. Smith, and S.R. Winter

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George L. Staby, Richard M. Basel, Michael S. Reid, and Linda L. Dodge

Three commercially available “anti-ethylene” treatment solutions were tested for their effectiveness in protecting carnations (Dianthus caryophyllus L. `Improved White Sim', `Atlantis', and `Nora'), Beard-Tongue (Penstemon hartwegii x P. cobaea `Firebird'), and Delphinium sp. from external ethylene levels ranging from 0.01 to 1.2 ppm. Flowers were treated according to label directions and then exposed to ethylene for 20 or 24 h at 20 to 23C after a 0-, 24-, or 48-h delay. Only the product containing silver thiosulfate (STS) provided protection against ethylene injury, whereas products containing inhibitors of ethylene synthesis identified as analogs of either aminooxyacetic acid (AOA) or aminoethoxyvinyl glycine (AVG) offered little or no protection. The safe commercial use of products containing STS is discussed.

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R.L. Bieleski, J. Ripperda, J.P. Newman, and M.S. Reid

We tested the hypothesis that premature leaf blackening in cut flower stems of Protea eximia (Salisb. ex Knight) Fourcade may be brought about by a low leaf carbohydrate status. Leaves on cut flower stems held in darkness blackened within 4 days, whereas those on stems held in a greenhouse remained healthy for 5 days. Leaf blackening was also retarded by supplying 1% sucrose in the vase solution; but other additives (hypochlorite, silver thiosulfate, bisulfite) were not effective. The hypothesis was further explored by examining postharvest carbohydrate changes in the leaf of cut flower stems held in light or darkness. At harvest, leaves contained very little hexose (< 1 mg·g-1 fresh weight), comparatively small concentrations of sucrose (≈ 5 mg·g-1 fresh weight) and starch (≈ 6 mg·g-1fresh weight), but high concentrations (≈ 30 mg·g-1fresh weight) of the polyol polygalatol. Starch and sugar contents of leaves held in darkness fell rapidly, to one-third of their initial level after only 1 day and to one-sixth after 3 days. In contrast, starch and sugar contents increased slowly in leaves of stems held in light to three times the initial level after 3 days. Polygalatol content was unaffected by any treatment. Removal of the inflorescence did not delay blackening of leaves held in darkness and did not affect their carbohydrate changes.

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Thomas M. Gradziel, Robert J. Knight Jr., William Reid, Chad E. Finn, John R. Clark, Eliezer S. Louzada, and Kim E. Hummer