Development of Harvest Control Methods for Strawberry Using Local Cooling on Fruit to Stop Maturation

Abstract

　Methods were tested in which fruits were cooled locally to stop maturation, followed by termination of cooling to restart maturation to control fruit harvest of strawberries. Two experiments were conducted: one in which the cooling was terminated all at once to concentrate the harvest in a short period, and the other in which the cooling and termination were repeated weekly to concentrate the harvesting on a specific day of the week. Non-linear regression analysis between temperature and fruit developmental rate (DVR) revealed that maturation was almost stopped below 5.9°C. A local cooling system that cooled only fruits below 5.9°C was constructed, and fruits were inserted into the system when turning stage. The termination of the cooling process all at once led to concentrated harvesting in a short period. In addition, weekly cooling and termination resulted in a considerable fruit yield concentrated on a specific day weekly. This suggested that methods combining local fruit cooling to stop maturation and termination of cooling could control the harvest period to some extent. This information would contribute to maximizing the sales of commercial strawberries because it enables fruit production control according to market demand.