Maturity and temperature influence ethylene‐promoted organ abscission in Camellia

Abstract

The influence of temperature (1–25°C) and maturity on organ abscission promoted by a range of ethylene concentrations (0.3–100 μl litre^‐1) was examined on stem explants of two Camellia cultivars ('Anticipation’ and ‘Donation'; C. salue‐nensis × C. japonica). Time to abscission of 50% of leaf and floral buds was measured. Leaves were most responsive during stem elongation following vegetative budbreak. In contrast, ethylene‐responsiveness of floral buds gradually increased with maturity. Low temperatures (1–5°C) reduced the rate of abscission response to ethylene at all concentrations, but with greatest effect at low concentrations (<2 μl litre^‐1). Floral buds of both Camellia cultivars were more sensitive to ethylene than leaves. Application of a high ethylene concentration correctly determined relative abscission differences for maturity effects, but inter‐organ differences required a range of ethylene concentrations. It is proposed that “responsiveness” be defined as differences in abscission response to a high ethylene concentration (e.g. 10 μl litre^‐1), whereas differences in abscission response to low ethylene concentrations (<1 μl litre^‐1) be defined as “sensitivity” differences.

Key words:

• plant growth regulators
• floriculture
• plant export
• sensitivity
• responsiveness