1968 Volume 37 Issue 1 Pages 20-29
In this investigation, the second crop on 8-year-old Masui Dauphine fig tree were employed to clear up the effects of acetaldehyde or ethylene on hastening the maturity of the fruits. That is, after the treatment with acetaldehyde (500ppm) or ethylene (500ppm) to the fruit at the best time of oleification the respiratory drift, contents of carbohydrates, concentrations of volatile substances such as acetaldehyde, ethyl alcohol and ethylene, and activities of plant growth substances in the fruits were determined unitl the maturity.
1. The maturity of the treated fruits with acetaldehyde or ethylene was markedly promoted in comparison to the untreated fruits. Between these volatile substances tested, acetaldehyde (matured 5 days after treatment) was more effective than ethylene (matured 8 days after treatment).
The mature fruits with these chemicals were the same in size, color, and reducing sugar and malic acid contents to those allowed to mature naturally.
2. The respiration rate of the treated fruit with acetaldehyde increased rapidly from the next day of the treatment, reached a climacteric maximum in respiration 2 days after treatment.
Thereafter the rate sharply declined, and again rose at maturity. While, those of the treated fruit with ethylene reached a climacteric maximum in respiration 4 days after treatment, thereafter the rate declined. The respiration rate of the treated fruit with acetaldehyde was significantly larger as compared with those of the fruit with ethylene throughout the season. However, respiratory quotients in both treated fruits with acetaldehyde and ethylene at the climacteric maximum were higher than 2.1.
3. The content of reducing sugar in the treated fruit with acetaldehyde increased rapidly on and after the climacteric maximum, and attained a maximum at the maturity. On the other hand, the content of malic acid in the treated fruit with acetaldehyde increased immediately, attained a maximum just before or on the climacteric maximum in respiration, and then decreased abruptly until the maturity. While, seasonal changes in contents of reducing sugar and malic acid in the treated fruit with ethylene were similar to those shown for the fruit with acetaldehyde.
4. As expressed in mg per 100g fresh matter, acetaldehyde and ethyl alcohol contents in the treated fruit with acetaldehyde increased immediately, reached a peak at the pre-climacteric periods in respiration (1 day after treatment), followed by the sharply depression and again rising at maturity. In the treated fruit with ethylene, the contents of acetaldehyde and ethyl alcohol reached a maximum at the climacteric peak in respiration (4 days after treatment). Thereafter the contents decteased abruptly and again rose at maturity.
5. Ethylene concentration in the treated fruit with acetaldehyde also increased rapidly, reached a maximum at the post-climacteric periods in respiration (at the beginning of fruit softening), afterwards the concentration decreased. While, ethylene concentration in the treated fruit with ethylene attained a maximum just after the treatment, followed by the sharp depression and again rising at the beginning of fruit softening.
6. In the treated fruits with acetaldehyde or ethylene, several endogenous growth substances such as IAA, IBA, IAN and GA3 like substances were identified by paper chromatographic method. Moreover, two different unknown growth substances were also detected. The activities of these endogenous growth substances were high at the stage of noticeable coloring in the skin, and were low at maturity.
7. From these data mentioned above, it was concluded that the effect of oleification on hastening the maturity of the fig fruit may be due to high enzymatic activity in the cells of the fruit tissue induced by the volatile substances such as acetaldehyde or ethylene shown in both process of oxidation of fatty acid and of decomposition of sugar.