COLD ACCLIMATION INFLUENCE POST-HARVEST NEEDLE RETENTION IN ROOT DETACHED BALSAM FIR (ABIES BALSAMEA (L.) MILL.)

Abstract

This study investigated the influence of cold acclimation on post-harvest needle retention in balsam fir (Abies balsamea (L.) Mill.) and explored certain physiological roles of roots and low temperature. In a controlled environment study, 18 month old seedlings with either detached or intact roots were exposed to a range of temperatures (-20 to 20°C) for different durations and selected physiological responses were measured. Cold acclimation of seedlings with intact roots resulted in 36% less needle loss, 76% lower fresh weight losses and 45% less water consumption when compared to those exposed to cold acclimation with no roots. A temperature of 5°C registered the lowest average daily water use of 0.16 ml/g/day, lowest needle loss of 7.1 mg/g and a positive weight gain (4%) when compared to -20, -5, 0 or 20°C. An acclimation temperature of -20°C reduced leaf chlorophyll content by 9x when compared to 5°C. Xylem pressure potential did not relate to needle loss. We hypothesize that roots play a key role in cold acclimation and needle retention by increasing membrane stability, preserving stomatal functions and maintaining chlorophyll content through yet unknown signals.