Volume XII JANUARY, 1922 Part I 



-i^ UJRA R? 



NEW \<)UV 

 BUTANICAL 



A COMPARATIVE STUDY OF WINTER WHEAT 



VAIIIETIE8 WITH ESPECIAL REFERENCE TO 



WINTER-KILLINGS 



By EGBERT NEWTON, M.S., B.S.A. 



UniversiUj of Albert n, Edmontmi. 



INTRODUCTORY. 



Winter wheat, where it can be safely grown, usually outyields spring 

 varieties quite markedly, but unfortunately ib is much more restricted 

 in distribution, due to its liability to winter-kiUing. Much progress has 

 been made with this and other crops in breeding for cold resistance by 

 empirical methods. It would appear, however, that greater and more 

 certain progress would be made if the nature of cold resistance in plants 

 were well understood. This subject has long been of interest to physio- 

 logists, and in its practical applications is of widest importance. The 

 northern limit of profitable growth of our staple crops marks also the 

 limit of profitable exploitation of our agricultural lands. The southern 

 farmer has likewise to meet the problems of the frost-killing of fruit 

 buds and flowers and the more tender winter cereals. 



HISTORICAL. 



The progress of our knowledge of the nature of cold resistance and 

 frost effects has been reviewed quite fully at different times by Abbe(i), 

 Blackman(5), Chandler (O) and others. Of the earlier investigations it 

 will be sufficient to note here in their order the most significant. 



The theory put forward in 17.37 by Duhamel and Buffon(ii) that 

 death from cold was due to rupturing of the cell walls by expansion on ice 

 formation, is of historical interest. It was almost a century later that 

 Goeppert(i3) found ice formation to occur in the intercellular spaces. 

 Sachs (.■?8) showed this to be the usual occurrence, and developed the 

 view, now generally considered erroneous, that disorganisation took 



■ This study was carried on in the lalioratory of Dr R. A. Gortner, Chief of the Division 

 of Agricultural Biochemistry, University of Miimesota, to whom grateful acknowledgement 

 is made for kind help and direction. The work was aided by election to the Shevlin 

 Fellowship. 



Journ. of Agric. Sci. xn 1 



