Ripening physiology and biochemistry of ‘Rocha’ pear as affected by ethylene inhibition

Abstract

Pear (Pyrus communis L.) is a climacteric fruit whose ripening behavior is highly cultivar-dependent. This study investigates the postharvest ripening physiology and biochemistry of ‘Rocha’ pear treated with 1-methylcyclopropene (1-MCP). Fruit from a single orchard harvested at the mature-green stage were treated with 0 (control), 150, and 300nLL−1 1-MCP, and allowed to ripen in air at 20°C. ‘Rocha’ pear without exposure to chilling ripened with a typical pattern of ethylene production and respiration rates. Inhibition of ethylene action by 1-MCP delayed the ethylene production peak and reduced its intensity by 60%. ATP concentration in control fruit was maximum after 7d and declined toward the end of the ripening period. 1-MCP induced a transient reduction of ATP concentrations and adenylate energy charge (AEC) during ripening. AEC of control fruit increased slightly during the first week and decreased to a stable value of 0.7 toward the end of ripening. Skin color and firmness of control fruit changed faster during the first week of ripening. 1-MCP induced a delaying in softening, in yellowing and in electrolyte efflux changes, but not impaired the ripening progress. In conclusion, ‘Rocha’ pear ripened immediately after harvest without chilling treatment or exogenous ethylene application and adjusted the AEC during ripening even with lower respiration rates induced by 1-MCP.