Session 02 Hormone metabolism and action

Abstract

Blueberries are an increasingly important h~ticultural crop in New Zealand and other coun~es. Fruit ripen over an extended period, with considerable differences in storage and other qualities. Tissue concentrations of abscisic acid (ABA), 1-aminocyciopmpane-l-carboxylic acid (ACC), malonyl-ACC and also ACC oxidase activity and ethylene evolution were determined at 5 stages of colour development on 2 harvest dates. These were related to &y matter, sucrose and reducing sugar content. ACC concentrations, and the proportion conjugated varied between harvest dates, while ethylene evolution and ABA concentrations were similar. ABA concentrations were high relative to other fruit, exceeding 10 nmole/g fw prior to full ripeness. ABA was present in higher concentration in mesocarp than in seeds or pericarp/cuticle. It is proposed that ABA is implicated in dry matter acquisition, but is not a primary determinant of colour development or ethylene regulation.