Ripening behavior of 'Columbia' and 'Gebhard' strains of red 'd'Anjou' pears after cold storage

'Columbia' and 'Gebhard' strains of red 'd'Anjou' pears (Pyrus communis L.) harvested at similar maturity exhibited different ripening behavior after monthly removal from 1 C storage in air. 'Columbia' fruit produced ethylene at higher rates than 'Gebhard' fruit during 15 days of ripening at 20 C after each corresponding storage interval. 'Gebhard' fruit required a longer period of chilling than 'Columbia' fruit to generate noticeable rates of ethylene during ripening. The unripened fruit of both strains contained similar amounts of ACC at each corresponding storage interval. At each corresponding ripened state, ACC content in 'Columbia' fruit increased 2 to 3-fold, while that in 'Gebhard' fruit changed very little. After sufficient chilling, 'Columbia' fruit were capable of softening to proper ripeness, and they developed buttery and juicy texture as indicated by the apparent reduction of extractable juice (EJ) content. 'Gebhard' fruit also softened but to a lesser extent than 'Columbia' fruit. Ripened 'Gebhard' fruit had only slightly lower levels of EJ than unripened fruit and did not develop a buttery and juicy texture after any storage intervals. Titratable acidity (TA) in fruit of both strains varied between for the 1988 and 1989 seasons but decreased significantly during storage in both years. Soluble solids concentrations (SSC) in both strains also varied seasonally but did not change during storage or ripening