RESULTS 



In order to relate cold acclimation to weather at Moscow, the temperature 

 associated with injury to 50 percent of the twigs was estimated for each sampling 

 date. That cold acclimation is closely related to the minimum temperature (Levitt 

 1972) is well illustrated in figure 2. Low levels of hardiness developed after the 

 first frost on October 3. Hardiness increased little during a relatively warm 

 period in late October, but increased greatly after the first cold wave in mid- 

 November. 



O 



o 



ZD 

 V— 



10 

 5 

 

 -5 

 -10 

 -15 

 -20 

 -25 

 -30 

 -35 

 -40 



* 



I 



1 



15 



AUG. 



1 



SEPT. 



15 

 SEPT. 



1 15 

 OCT. OCT. 



DATE 



1 



NOV. 



15 



NOV. 



1 



DEC. 



Figure 2 . --Development of hardiness in relation to daily minimum temperatures. Stars 

 denote the temperature associated with injury to 50 percent of the twigs at each 

 sampling date. 



5 



