F. KiDD AND C. West 9 



Table VI. 



Effect of a loiv temperature at different stages in the develop- 

 ment of " Uruguay " oats. 



Treatment Result of treatment 



Seeds kept at 6°- Followed by a temperature of 25° C. Plants flowered during the 

 9° C. for 5 days until germination was completed same season 



Seeds kept at 25° C. Followed by a temperature of (i°- Plants did not flower during 

 for 1-2 days i)° C. for 5-7 days (i.e. until ger- the same season 



mination was completed) 



If the exposure to the low temperature occurs 2-3 days after sowing 

 at normal temperatures {e.g. 24° C.) it is necessary that the period of 

 exposure to the low temperature be many times as long iii order to 

 obtain the same result as when the exposure is made during the first 

 few hours after sowing (see Table VII). 



Table VII. 



Influence of low temperature on the time of culm -formation in 

 " Petku^er" winter rye sown in the sjning. 



Treatment 



Germination period Followed by a period 



at 24° C. at 0° to - 5° C* Result of the treatment 



3 days 25 days Formed flowering-stems the same year after 68 



days 

 3 „ 3 „ . 



3 „ 1 5, \- Did not form flowering-stems the same year 



3 „ „ J 



* The plants were subsequently grown under natural conditions. 



In parallel experiments carried out with so-called summer-annuals 

 of the same varieties it was found that exposure to low temperatures 

 during germination did not appreciably influence the time at which 

 culm-formation took place^ (see Fig. 3). 



(c) Electrical Discharge. 



Results of empirical experiments dealing with the effects of electrical 

 discharge upon seeds during germination are on record. The interesting 

 aspect of these experiments from our point of view lies in the fact that 

 it is stated that brief exposure of seeds prior to and during germination 



^ Gassner and Grimme (11) have shown that plants which require a period of low 

 temperature to bring about complete development, can withstand extreme cold, whereas 

 plants which do not need a low temperature, are unable to withstand cold. 



