In vitro growth and ripening of strawberry fruit in the presence of ACC, STS or propylene

Abstract

SummaryStrawberry (Fragaria ananassa Duch.) fruit exhibit limited capacity for continued development following harvest. This problem can be circumvented by maintaining harvested strawberry fruit in solutions containing sucrose and a bactericide. In this study, we investigated the respiratory and ethylene production kinetics and ethylene responsiveness in strawberry fruit harvested immature and ripened in vitro in the presence of propylene. The effects of 1‐amino‐cyclopropane‐1‐carboxylic acid (ACC) and silver thiosulfate (STS) alone and in combination were also examined. Respiration and ethylene patterns of fruit harvested green and developed in vitro declined with maturation and ripening, as did those of field‐grown fruit harvested at different stages of ripeness. Exposure of detached green strawberry fruit to 5000 μl litre‐1 propylene failed to stimulate respiration or ethylene production, but advanced pigmentation changes and fresh‐weight gain significantly. Excised fruit provided with 1 mol‐3 ACC exhibited increased ethylene production, enhanced fresh‐weight gain, and accelerated anthocyanin accumulation, but showed no change in respiration. The developmental response of harvested strawberry fruit to propylene or ACC was dependent on fruit maturity at harvest, with white fruit exhibiting greater insensitivity compared with green fruit. Silver thiosulfate (0.5 mol‐3) applied alone or in combination with ACC failed to delay ripening in excised strawberry fruit. These experiments demonstrate that ripening in detached strawberry fruit can be modified by ethylene only in green fruit that are provided with a carbohydrate source. Ethylene, when applied exogenously as ACC or propylene to green fruit, can slightly increase fruit growth and the rate of colour development.