Carbon Dioxide Effects on Fruit Respiration . II. Response of Avocados, Bananas, & Lemons.

,Most studies concerning the effects of the gas composition of the atmosphere surrounding fruit have been directed toward the response of the combined changes of oxygen an(d carbon dioxide. This was a result of the economic need for methods of prolonging the storage life by the use of modified atmospheres at temperatures above those which cause chilling injury. Several studies have been concerned with the effects of decreased oxygen alone. Parija (15) obtained minimum carbon dioxide prodluction by apples at 5 % oxygen. Kidd and WVest (12) found an acceleration of the onset of the climacteric in apples by oxygen tensions higher than in air. Singh et al. (19) reported for mangos a critical oxygen level of 9.2 % below and above which carbon dioxide evolution increased. The studies of Claypool and Allen (6, 7) with apricots, plums, peaches, and pears indicated a decreased rate of CO., output at oxygen tensions below air. For a more comprehensive treatment of this subject the recent review by Biale (3) is suggested. For the avocado, a fruit which exhibits a climacteric pattern of respiration, it was shown by Biale (2) that low oxygen reduced the respiratory activity during the preclimacteric period andl the (luration of the preclimacteric period was prolonged. Within the range of 2.5 to 21 % oxygen the time required to reach the climacteric peak was extended in proportion to the decrease in oxygen tension and the intensity of respiration at the peak was reduced. No significant stimulation of respiration wvas observed by concentrations of oxygen above 35 %. However, the cumulative carbon dioxide production from the time of picking until the climacteric peak was not changed by the treatment at any level of oxygen. In the case of the banana, another fruit with a climacteric pattern, it was found by Kidd and West ( 11 ) that storage in 2.5 and 5.0 % oxygen did not materially decrease the rate of ripening. On the other hand, Leonard (13) observed a reduction in CO, liberation by fruit stored in oxygen concentrations lower than air and