Caracterizações ultraestruturais e fisiológicas de pedúnculos e frutos de café com diferentes forças de desprendimento

Abstract

This study aimed to investigate the physiological events involved in coffee detachment during the various stages of ripening, linking them with the different forces of detachment used for its harvesting, as well as the existence of an abscission zone in coffee fruits. Peduncle and fruit of Coffea arabica cv Icatu Amarelo were collected in the stages of ripening “verde”, “verde-cana” and “cereja” in forces intervals of 10 - 13 N and 8 - 9,9 N, 6 – 6,9 N and 5 - 5,9 N, 4 - 4.9 and 2 - 3,9 N, respectively. Ultrastructural and anatomical evaluations were performed on the connection region between peduncle and fruits, and biochemical analyzes were performed in peduncle and fruits separately. It was not observed a clear abscission zone between the peduncle and fruit of coffee plants, but can be observed a disruption of the cells over the maturation period. This disruption can be related to the increase in activity of cell wall degrading enzymes, polygalacturonase and cellulose, in the final stage of maturation, as well as the increase of lipid peroxidation. Polyamine levels were higher in the initial stage of ripening, indicating an antagonistic regulation with ethylene synthesis. In general there is a clear physiological difference between the maturation stages which explain the different forces of detachment used in each. In this way, it can be concluded that Coffea arabica cv Icatu Amarelo does not have an clear abscission zone between peduncle and fruit. Moreover the decrease of fruit-detachment force is clearly related to morphological and biochemical changes during the maturation process.