Effects of exogenous application of jasmonates and 1-methylcyclopropene (1-MCP) for pre- and postharvest control of peach and apple fruit ripening

In freestone peaches, the ripening process is typically divided into two stages: an early phase during which softening proceeds slowly, and a melting stage with a rapid loss of firmness associated with a dramatic increase of ethylene emission. On the contrary, in apple, three distinct phases of ripening could be identified: a first one during which fruit soften slowly, a second one characterized by a more rapid decrease in firmness, and a final phase of slow softening. A low basal rate of ethylene production is sufficient to promote the early phases of apple softening, while the faster firmness decline is related to an increase in the Internal Ethylene Concentration (IEC). With the intent of improving fruit appearance and quality and for a better understanding of the relationship between ethylene production and fruit softening, two chemicals, n-propyldihydrojasmonate (PDJ) and 1-methylcyclopropene (1-MCP), were applied on nectarines ('Stark Red Gold' or 'Laura') and apples ('Fuji' or 'Mondial Gala') in the open field and postharvest conditions. Both chemicals induced distinct effects on the two species. In fact, PDJ inhibited ethylene production in peach while it tended to increase it in apple; on the contrary, 1-MCP reduced ethylene production in apple and stimulated it in peach. These opposite trends induced by the two chemicals were also characterized by different effects on flesh firmness (FF) and the main fruit quality traits.