
TY  - JOUR
A1  - Johnston, RD 
T1  - Control of water movement by stem chilling
JF  - Australian Journal of Botany
JO  - Aust. J. Bot.
Y1  - 1959
VL  - 7
IS  - 2
SP  - 97
EP  - 108
KW  - 
UR  - https://doi.org/10.1071/BT9590097 
N2  - Apparatus is described whereby a portion of the stem of a young tree of Pinus radiata D. Don could be maintained at a temperature close to freezing point, while the transpiration of the upper part of the plant was measured. The freezing point of the stem was shown to be about -2&deg;C, and while the stem temperature was kept above this point transpiration continued normaiiy; freezing the stem resulted in a decrease in transpiration, after a short lag period, and within 3 hr transpiration was almost undetectable. When the stem temperature was maintained at just below the freezing point for 7 days, the leaf water deficit of the shoot rose from 10 to 47 per cent., but returned to normal values within 4 days after freezing was stopped; the plant showed no signs of damage due to freezing. Field trials, using solid carbon dioxide as a refrigerant, showed that growth was reduced considerably on a branch chilled to -4&deg;C for 7 days, but needles remained alive and appeared healthy. Lower temperatures caused damage to needles and twigs. 
ER  -

