Canadian Forest Service Publications

Effects of xylem cavitation and freezing injury on dieback of yellow birch (Betula alleghaniensis) in relation to a simulated winter thaw. 2000. Zhu, X.B.; Cox, R.M.; Arp, P.A. Tree Physiology 20: 541-547.

Year: 2000

Issued by: Atlantic Forestry Centre

Catalog ID: 6228

Language: English

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Shoot dieback, shoot growth, stem xylem cavitation, stem and root freezing injury, and root pressure were measured in 2-year-old, cold-hardened, potted yellow birch (Betula alleghaniensis Britt.) Seedlings that had been subjected to a simulated winter thaw for 0, 5, 10, 19 or 27 days followed by 10 weeks at -10 C. Stem xylem cavitation was determined as percent loss of hydraulic conductivity. Stem freezing injury was measured as electrolyte leakage (EL). Root freezing injury was determined by EL and by triphenyl tetrazolium chloride (TTC) reduction. Thaw duration was significantly correlated with dieback, new shoot growth, stem xylem cavitation, stem and root freezing damage, and root pressure (P < 0.05). In particular, shoot dieback was positively correlated with stem xylem cavitation (P < 0.001), but only weakly correlated with stem freezing damage (P < 0.05). In roots, freezing damage was negatively correlated with root pressure (P < 0.05), which, in turn, was negatively correlated with residual stem xylem cavitation after root pressure development. In stems, there was no correlation between freezing damage and xylem cavitation. We conclude that long periods of winter thaw followed by freezing resulted in freezing injury to roots concomitant with a reduction in root pressures, leading to poor recovery from freezing-induced xylem embolism.