Supercooling and freezing in the main stem of Valencia orange trees

摘要: Freeze avoidance (supercooling) and subsequent freezing of freeze-sensitive Citrus was determined in controlled environment tests on potted 1- to 2-year-old sweet oranges trees, sinensis (L.) Osbeck cv. Valencia rough lemon (Citrus jambhiri Lush.) rootstock. Cold hardening done controlled-environment, walk-in rooms with programmed light/temperature regimes. Trees were frozen a separate room monitored multiple thermocouples attached or inserted into different tissues. Apparent rate ice propagation apparent initial ice-nucleation temperature significantly correlated cold-hardened trees. Supercooling levels also increased Leaves not critical sites for catalyzing the main stem, neither bark girdles nor partial stem severance overlapping cross-sectional cuts slowed rapid wood. largely transient location. Decreases supercooling induced short periods crystallization trees during repeated freeze cycles. These fully restored original longer thaw. The perceived nucleation site necessarily where visible kill developed, direction more characteristically from lower upper vice versa nonhardened