Gas diffusion in bulky plant organs.
Cameron, Arthur Clifford.
Ph.D. dissertation, University of. California, Davis, 1982. 109 pp.
1982
บทคัดย่อ
In a quantitative approach to the study of gas diffusion in bulky organs, models were developed from Fick's general laws of diffusion and the critical assumptions specified. Steady state methods were developed for the concurrent determination of the resistance to oxygen, carbon dioxide, ethylene and water vapor. The resistance of apple and tomato skin to oxygen, carbon dioxide and ethylene were generally found to be similar but the resistance to water vapor diffusion was shown to be 20 and 1000 times lower for the skin of apple and tomato respectively. A nonsteady state method, based on kinetic analysis of the efflux of preloaded ethane gas was developed for quantitative measurement of resistance to ethylene and shown to correlate well with values of R(,C(,2)H(,4)) measured using the steady state method. The resistance network analogy was used to model paths of gas diffusion in apples and tomatoes. Using both steady state and efflux methods, it was shown that the stem scar of tomatoes accou
nts for 94%, 81% and 67% of the exchange of ethylene, carbon dioxide and water vapor respectively. The calyx end of apples was found to account for 29%, 24% and 2% of the exchange of ethylene, carbon dioxide and water vapor respectively. Evidence is presented which suggests that lenticels do not play a major role in gas exchange of apples. Resistance values (sec cm('-1)) extracted from the literature are presented. The importance of these values to the postharvest storage of fruits and vegetable is discussed.