Induction Period and Threshold Temperatures for Premature Ripening in ‘Bartlett’ Pears1,2

Continuous exposure of pears to 7.2°C (night) - 21.1°C (day) for 2 days or 10°C - 21.1°C for 9 days or 7.2°C - 26.7°C for 21 days induced the physiological disorder, premature ripening, during the month immediately preceding normal harvest. During the same period, premature ripening did not develop with temp exposures of 12.8°C - 21.1°C or with 7.2°C - 32.2°C. Cool temp 6 to 9 weeks prior to harvest may also cause premature ripening to occur but the fruit will recover to normal behavior if subsequent temp are above the threshold level.