Studies on the Mechanism of Ethylene Action for Fruit Ripening

II. Respiration Response of Banana Peel and Pulp to Ethylene Treatment

Abstract

Respiration response of peels and pulps of banana fruits to ethylene was investigated.
Effect of cutting of peels and pulps on respiration was observed with three sizes of slices (4×4cm, 2×2cm, 1×1cm). Green banana peel sections of all sizes showed an initial burst of respiration immediately after cutting and minimized within 8 hours. But pulp sections did not show such burst of respiration after cutting. Both peel and pulp sections exhibited broad peak of respiration 13 and 20 hours after cutting. Respiration rates of smaller size sections were higher than those of larger size sections.
Peel and pulp sections were treated with 0.1, 1, 10, 100, and 1000ppm of ethylene. Low concentration of ethylene (0.1ppm) hardly stimulated respiration and 1ppm of the gas stimulated it. Saturated concentration of ethylene for stimulative effect of respiration was more than 10ppm on both sections of banana fruits.
Peels and pulps were treated with 100ppm of ethylene for different periods. When ethylene was applied, respiration of the peels was stimulated, and it was decreased rapidly when ethylene was removed. Respiration of pulps was decreased after treatment for 6 hours, but it increased constantly after treatment for more than 12 hours.
Changes of respiration rate of peel and pulp sections at each stage of ripening of banana fruits stimulated previously with 100ppm of ethylene were observed. Pulps showed a climacteric pattern of respiration and produced ethylene as a ripening hormone. On the other hand, peels did not show climacteric rise and ethylene production of peels was not observed except senescent stage.
Respiratory quotient was measured during ripening. Little or no change of RQ occurred in peels and its value remained approximately 1, but RQ of pulps increased 0.7 to 1.5 gradually as ripening progressed.