ISHS Acta Horticulturae 514: XXV International Horticultural Congress, Part 4: Culture Techniques with Special Emphasis on Environmental Implications
THE ROLE OF GIBBERELLIN AND PHYTOCHROME IN DIF-MEDIATED STEM ELONGATION |
| Authors: | G. Grindal, R. Moe, O. Junttila |
| Keywords: | cucumber, DIF, far-red light, gibberellin, pea, stem elongation, thermoperiodicity |
| Abstract:
The effect of daily temperature alternations on morphology of commonly propagated ornamentals is well known. Here we attempt to summarise current knowledge on the importance of gibberellin (GA) and phytochrome for development of taller stem and internodes under a combination of a high day (DT) and low night temperature (NT) (positive difference between DT and NT, positive DIF) than under a low DT and high NT (negative DIF). Current results indicate that the content of GA1 plays a key role in thermoperiodic stem elongation in several species. Under negative DIF the GA1 level in the elongating tissue is lower than under positive DIF. Day extension with far-red light neutralises the effect of negative DIF, while red light has the same effect as no additional light at all. Lack of phytochrome B in cucumber makes the plants unable to express thermoperiodisity. The interaction between phytochrome and GA in controlling temperature regulated stem extension is not known. | |
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