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The procedure of in vitro propagation of Harpagophytum procumbens using shoot tips was developed. Shoot tips were cultured on Schenk and Hildebrandt (SH) agar medium supplemented with 0.57 µM indole-3-acetic acid (IAA) in combination with various cytokinins: 6-benzylaminopurine (BAP), thidiazurone (TDZ), kinetin or zeatin at four concentrations (2, 4, 6 or 8 µM). The best shoot multiplication rate (11.2 shoots/explant for 5 weeks) was achieved in the presence of 6 µM TDZ. The shoots were small and their elongation on SH medium supplemented with gibberellic acid (GA3 ) was necessary. Shoots of H. procumbens were rooted on full-strength or half-strength Murashige and Skoog (MS) agar medium either with or without auxin. Plantlets were transferred into pots and maintained in the greenhouse. After 1 month, the overall survival of plants was 83% but it decreased to 27% after 6 months.
The experiment determined the effect of gibberellic acid applied prior to harvest on the contents of plant pigments in cut leaves of wild ginger (Asarum europaeum L.), cultivated in an unheated plastic tunnel and in the field. Foliar application of GA3 at a concentration of 100, 200, 400, 600 mg x dm-3 was repeated four times every two weeks. It has been proven that pre-harvest spraying of plants with gibberellic acid at a concentration of 100 mg x dm-3 has a positive effect on the content of photosynthetically active pigments in the leaves of A. europaeum cultivated in an unheated plastic tunnel. Application of GA3 at a concentration of 600 mg x dm-3 led to the accumulation of the greatest amount of anthocyanins in the leaves of Asarum europaeum cultivated both in the unheated plastic tunnel and in the field. The response of plants to GA3 application, expressed in the amount of flavonoids, depended on conditions related to the cultivation site. Pre-harvest treatment of A. europaeum plants with gibberellic acid at concentrations of 100-600 mg x dm-3 reduced the production of flavonoids in tunnel-grown wild ginger, but enhanced their accumulation in plants cultivated in the field. Pre-harvest application of gibberellic acid did not affect the fresh weight or dry mass content in plant material.
Cytoplasmic and salt-extracted peroxidase and IAA oxidase activities were studied in Phaseolus vulgaris hypocotyls treated with gibberellic acid (GA, 200 µM), naphthyl acetic acid (NAA, 100 µM) and distilled water control (DW). Peroxidase activity was assayed with four hydrogen donors during the initial phase of hypocotyl elongation. Though peroxidase activity showed a decreasing trend with time in all the hydrogen donors studied; considerable variation with different hydrogen donors was observed. NAA had maximum peroxidase activity as compared to DW or GA treatment. The activity showed a clear inverse correlation with hypocotyl growth. IAA oxidase activity showed a similar trend with growth as peroxidase activity. A highly significant correlation was observed between peroxidase and IAA oxidase activities and high molecular weight xyloglucan content (P<0.001). Finally, the possible role of peroxidase and IAA oxidase activities in hypocotyl elongation growth is discussed.
The research focused on the effect of GA₃ and BA on the yield of Allium karataviense ‘Ivory Queen’. The substances in concentration of 500 mg₃·dm⁻³ were applied in the form of a 60-minute bulb soaking prior to planting or plant spraying in the green bud phase. It was discovered that GA₃ applied in the both forms causes the inflorescence shoot elongation and the increased number of flowers in inflorescence, and increases the total yield expressed in the bulb weight. When applied in the form of plant spraying, it increases the number of bulbs in the total yield. Plant spraying with BA leads to the production of a greater number of flowers in inflorescence. BA application in the both forms increases the total yield expressed in the bulb weight.
In this study, favorable carbon-nitrogen ratio for high yields of gibberellic acid (GA₃) production from Pseudomonas sp. was investigated. First of all, optimum carbon (glucose, maltose, sucrose, fructose, lactose) and nitrogen (KNO₃, NH₄C1, NaNO₃, urea, glycine) sources among the others were chosen. The highest yield of GA₃ productivity was found in growth medium supplemented with fructose (168.5 mg/L). NaNO₃ was found as a suitable nitrogen source (141 mg/L). Then, in order to determine the optimum carbon-nitrogen ratio, different concentrations of carbon (from 50 mM to 150 mM) and nitrogen (from 17 mM to 47 mM) sources were added in culture media. As a result, optimum carbon-nitrogen ratio for GA₃ production from Pseudomonas sp. was found to be 100:17 mM.
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