Vernalization and Photoperiodism — 26 — 



A Symposium 



The scores are slightly higher than those of the control series vernalized 

 for 12 weeks continuously, thus proving reversibility of the vernalization 

 process in both directions. The efficacy of the high temperature devernaliza- 

 tion in these experiments depends upon the duration of the previous low- 

 temperature period and thus upon the "intensity" of vernalization; this 

 aspect is now being investigated. 



Field experiment at East Mailing Research Station, 1942. — - Soviet 

 research on vernalization had indicated that increases in yield could be ob- 

 tained with spring cereals, and techniques for the treatment of spring 

 cereals were included by Lysenko (see I.A.B. 1935) and Dolgusin (ibid.) 

 in their recommendations to agronomists. The requisite temperatures 

 varied with the type of cereal used: thus 0-2°C. was suggested for winter 

 wheat and barley; 2-5° for hard late wheats, spring barley, and oats; and 

 10-12°C. for soft spring wheat and hard early wheat. The duration of ver- 

 nalization recommended varied from 35-40 days for winter wheat, to 5-7 

 days for early spring wheat. 



In the field experiment under discussion (Gregory, 1945), two each of 

 the cereals wheat, barley, and oats were used. Vernahzation treatments 

 were used covering the range of temperatures recommended by the Soviet 

 agronomists, and at each temperature two durations, one long and one short, 

 were employed. 



The varieties used and the vernalization treatments given are stated 

 below : 



Wheat 

 Barley 

 Oats 



Temperature : 



37°F.(2.8''C.) 

 40°F.(4.4°C.) 

 45°F.(7.2°C.) 

 50°F.(10°C.) 



Variety : 



Little Joss, April Bearded. 

 Plumage Archer, Spratt Archer. 

 Victory, Resistance 



Duration of vernalization 

 IN weeks : 



4 and 2 

 3 and 2 

 3 and 2 

 2 and 1 



Sowing date (1) April 6-11; (2) May 4-9. 



There were thus, in all, six varieties with four vernalization temperatures 

 each with two durations of treatment and in addition two controls. The 



