Localization of Endogenous Growth Substances in Freesia hybrida ‘Moya’ Corms Before and After a Heat Treatment1

Abstract

Freesia hybrida Bailey ‘Moya’ corms were analyzed for extractable indole-3-acetic acid (IAA), abscisic acid (ABA) and conjugated ABA (conj.-ABA) before and after 13 weeks of storage at 30°C. After 13 weeks of 30° storage, which is required for emergence, IAA levels did not change in the apical node + bud; however, there was a decrease in ABA and no statistically significant change in the conj.-ABA levels. IAA level increased (0.5 to 14 ng/g fresh weight) in the lateral buds after 13 weeks of heat while the ABA and conj.-ABA did not statistically change. Over the same period, IAA increased slightly (3 to 7 ng/g fresh weight) in the remaining corm tissue while ABA and conj.-ABA levels remained statistically constant.

Corm and Shoot Development of Freesia hybrida ‘Super Emerald Mixture’ as Related to Endogenous Abscisic Acid and Indoleacetic Acid Levels in the Developing Corm1

“…1) which makes interpretation of changes in ABA, conj-ABA and IAA contents within the corm difficult. Small changes in levels of growth substances within a localized portion of the corm may not have been detected because of the dilution effect when analyzing the whole corms as discussed in a companion article (11).…”

“…In Europe a 3 to 5 week 13°C cold storage treatment of corms after the completion of the 13 weeks of 30° ± 2° storage just prior to planting is used to hasten flowering (1, 2, 3, 5, 9,11). This procedure, however, was not successful under Israeli (5) or Minnesota growing conditions (Gilbertson-Ferriss, unpublished data) possibly because of warmer fall temperatures than in northern Europe.…”

“…Flower initiation in Freesia hybrida is a temperature-dependent process (7,10,11). If plants have seven visible leaves, floral initiation process will be completed after 6 weeks at 13°C (7).…”

“…If plants have seven visible leaves, floral initiation process will be completed after 6 weeks at 13°C (7). Initiation is irreversible after 3 weeks at 5° (11) and after 4 weeks at…”