504 



Journal oj Agricultural Research 



Vol. XIII, No. 10 



Table XI. — Summary of the relative freezing points of the leaves and leaf sap of various 



winter cereals 



o Average of determinations of November 27, December 17, and January 10, only. 



The average for the three tests show practically the same depression 

 of the freezing point for rye, Kharkof wheat, and Tennessee Winter 

 barley, it being decidedly less for these grains than for Fultz Winter wheat 

 and Culberson Winter oats. As mentioned in connection with the data 

 for each test, the depression of the freezing point seems to 'depend more 

 on the conditions of the leaves with respect to turgidity than on variety 

 characteristics. 



RELATION OF TURGIDITY TO DENSITY OF SAP AND RESISTANCE TO 



LOW TEMPERATURE 



Because of the apparent relation between turgidity and sap density 

 observed in these experiments, it seemed desirable to investigate this 

 phase more thoroughly. Accordingly seedlings of hard wheat (Turkey), 

 soft wheat (Fultz) , and winter oats (Culberson) , grown in the greenhouse 

 were removed from the soil and one set was exposed to sunlight at 

 room temperature from two to three hours and another set placed in 

 the same location as the first but with the roots immersed in water. 

 The freezing point of the leaves was then determined by the direct 

 method. The results are shown in Table XII. 



Table XII. — Relation of turgor to tlie freezing point of leaves 



