Original Articles

Exogenously applied ethylene reduces the cold requirement for ripening of pears (Pyrus communis L.) cv. Forelle

Published in: South African Journal of Plant and Soil
Volume 18, issue 4, 2001, pages: 147–153
DOI: 10.1080/02571862.2001.10634421
Author(s): P.G. du ToitDepartment of Horticultural Science, South Africa, G. JacobsDepartment of Horticultural Science, South Africa, M. HuysamerDepartment of Horticultural Science, South Africa, D.M. HolcroftDepartment of Horticultural Science, South Africa

Abstract

‘Forelle’ pears harvested at commercial maturity were treated with ethylene at 0, 10 or 100 μl 1−1 for 24 hours at 20°G before being stored at-0.5°Cfor 12 weeks. Periodic sampling of the fruit showed that both ethylene treatments significantly hastened ripening compared to untreated fruit, as judged by changes in peel colour from green to yellow and fruit softening. Differences observed between fruit treated with the different ethylene concentrations were negligible and both treatments reduced the recommended 12 weeks of cold storage. The following year, Forelle pears were harvested at three stages of maturity, namely pre-optimum, optimum and postoptimum and treated separately with 50 μl 1−1 ethylene at 20°C for 12, 24 and 36 hours. Thereafter, the pears were stored at-0.5°C for 12 weeks and periodically sampled to evaluate ripening. Harvested fruit of all harvest maturities required a minimum of 24 hours of ethylene exposure to attain a physiological response in ground colour and firmness, but softening preceded colour changes. Four weeks at-0.5°C resulted in sufficient yellowing for marketing of optimally and post-optimally harvested fruit, while pre-optimally harvested fruit required eight weeks at −0.5°C. Yellowing and softening differed significantly between harvest maturity. The quality of Forelle pears held at −0.5°C was not adversely affected by ethylene, regardless of the harvest date. Ethylene applications hastened the ripening of Forelle pears and reduced the cold requirement, but cannot totally replace the cold storage requirement.

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