ETHYLENE-INDUCED RISE OF ABSCISIC-ACID LEVELS AND ACC OXIDASE ACTIVITY IN IMMATURE MELONS

Immature cantaloupe charentais melons (Cucumis melo L. cv. Alpha) were harvested ten days before their optimum picking date, treated for 2 d with 100 ppm ethylene and kept at 21 degrees C 85% r.h. for 10 d for further ripening. The treated immature fruits were compared with untre ated immature or mature melons. CO2, ethylene, ACC oxidase activity an d abscisic acid levels were measured. Ethylene treatment induced ACC o xidase activity in immature fruits, whereas ACC and MACC levels remain ed low, which may indicate a lack of ACC synthase activity. Ethylene t reatment also induced an increase in ABA levels in both skin and pulp. Relationships between ethylene and ABA content is discussed.