Effects of Storage Temperature and Exogenous Ethylene on Postharvest Ripening of Jingbai Pear

Freshly harvested 'Jingbai' pears (Pyrus ussuriensis Maxim.) were subjected to precooling for 12 h, followed by either direct storage at 6 different temperatures or storage at (20 ± 1) ℃ after 24 h fumigation at 20 ℃ in the presence of commercial ethylene gas or that released from four bananas with medium degree of maturity. For investigating the effects of temperature and exogenous ethylene on the ripening process and quality of 'Jingbai' pears, ethylene production, respiration rate, fruit firmness, SSC (soluble solid content), pH, E and h values of fruit skin color, weight loss weight loss and percentage of diseased fruits were periodically measured during storage and sensory evaluation was also carried out. Temperature and exogenous ethylene treatment both markedly influenced the ripening process and quality of 'Jingbai' pears. Fruit firmness exhibited an extreme significant linear negative correlation with ripening time (P0.01). Higher and lower temperatures caused inconformity between fruit skin color and softening rate, and an appropriate temperature (14 ℃) delayed the start time of ethylene peak, but higher temperatures (28 ℃) restrained the synthesis of ethylene and the softening of fruit flesh and resulted in a higher respiration rate, weight loss and percentage of diseased fruits and lower ethylene production. Exogenous ethylene treatment improved fruit respiration and ethylene production, and the application of a proper concentration promoted fruit ripening and gave a uniform degree of maturity and optimum fruit quality. Considering our findings collectively, suitable temperatures for 'Jingbai' pear ripening should be between 17 ℃ and 23 ℃ (20 ℃ found optimum) and the optimum concentration of ethylene is 100 μL/L.