Effect of CCC on the gibberellin content of excised sunflower organs.

CCC was shown to be effective in retarding stem growth of sunflower; this effect was overcome by gibberellic-acid application. Using an agar-diffusion technique, the gibberellin (GA) content of sunflower apices treated with CCC was found to be significantly reduced as compared to controls. Similarly, the GA content of agar diffusates obtained from 2-day-old sunflower root tips treated with CCC was also significantly reduced as compared to controls.Root exudate or bleeding sap obtained from mature CCC treated sunflower plants contained no measurable GA-like substance, although it could not be argued that this was due to suppression of GA synthesis in the root systems.