Gibberellin-like activity from organs of Tulipa Gesneriana

Abstract

Quantitative determinations of extractable gibberellin-like substances (GA's) were made from various organs of Tulipa Gesneriana L. cv. 'Elmus' during cooling and forcing. The barley half-seed and dwarf pea bioassays were used to determine the activity. Shoot tissue contained the greatest levels of GA activity followed by scale and then root tissue. Further division of the shoot and scale tissues showed that the developing flower and bulblets contained the majority of the GA's in these tissues. Quantitative and also qualitative changes, as assessed by chromatogram comparisons, occurred in GA's during the cooling and forcing treatments. The exact pattern of changes within each organ was dependent on the bioassay used. Shoot tissue appeared to be the most sensitive organ to changes in temperature.