THE PRODUCTION AND PHYSIOLOGICAL EFFECTS OF ETHYLENE DURING ONTOGENY AND AFTER HARVEST OF LITCHI FRUITS
Jiang Jian-ping, Su Mei-xia and Lee Pei-man (Dept. of Hort., South China Agricultural University)
The respiration and ethylene production of litchi fruits (Litchi chinensis Sonn.) during their ontogeny and after the harvest have been studied.The respiration and ethylene production of litchi fruits declined throughout their ontogeny. The respiration of the harvested mature fruits did not increase 25 hours after treatment with Ethephon. Therefore, litchi was a nonclimacteric fruit but the sensitivity of its respiration to external ethylene was lower than typical nonclimacteric fruits.The amount of ethylene produced by the peel of mature litchi was 86 times of that produced by the same fresh weight of the aril and seed, indicating that the peel had high capacity to produce ethylene. The activities of polyphenol oxidase and peroxidase in the peel could be promoted by ethylene treatments. It is suggested that the browning of the litchi peel is related to its high capacity to produce ethylene. The respiration and ethylene production of litchi fruits could be strongly inhibited by low temperature (5℃). After the fruits were transferred to 25℃, the respiration and ethylene production of the fruits increased rapidly and the concentration of internal ethylene finally reached the peak value of 17.6 ppm. This may cause an increase in activities of polyphenol oxidase and peroxidase in the peel. To extend the shelf life of litchi fruits it is helpful to eliminate ethylene from the environment of the fruits or inhibit its production by the fruits with some effective absorbents or inhibitors during this period.