Summary
The cytokinin content of root exudate of sunflowers increases during the exponential growth phase of the plants. The concentration of cytokinins drops, however, by a factor of ten when the plants have reached their final size. The reduced supply of cytokinins from the root to the shoot is regarded as one of the factors bringing about shoot senescence.
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Sitton, D., Itai, C. & Kende, H. Decreased cytokinin production in the roots as a factor in shoot senescence. Planta 73, 296–300 (1967). https://doi.org/10.1007/BF00386684
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DOI: https://doi.org/10.1007/BF00386684