CHAPTER VI 

 CLASSIFICATION AND INHERITANCE IN WHEAT 



Studies of genetics have led to the adoption of a particular 

 meaning which is understood when we speak of an inherited 

 character. It is the final result of the interaction of many 

 inherited factors plus the environment. The factors are the 

 inheritance and the ultimate character is the manner of reaction 

 under the special growing conditions to which the organism is 

 subjected. What is inherited is the ability to react in a particu- 

 lar manner in a given place and not the character itself. 



Genetic Classification. Classification of cultivated varieties of 

 crops is made in much the same manner as the botanical classifica- 

 tion of wild species. With crops, there is as a rule considerable 

 experimental evidence of genetic relationship. The ultimate 

 aim of crop classification should be genetic in order that it may be 

 of greatest value. Closeness of relationship as determined by 

 the ease of crossing and the degree of sterility is frequently made 

 the basis of species groups in some crops. In other crops no 

 sterility is obtained in so-called species crosses. Only relatively 

 stable characters which are not easily modified under different 

 environmental conditions are considered of major classification 

 value. 



After placing cultivated crops in groups which are roughly 

 analogous to botanical species, the next step is more clearly 

 to separate different categories of a lower order of classification. 

 These are the varieties. Varieties are not necessarily genetic 

 entities but may be groups of similar forms which resemble each 

 other more than individuals belonging to another variety. All 

 members of a variety are similar to each other in major botanical 

 characters. 



Such a variety classification is of utmost importance. In the 

 past the variety studies made in the United States by the different 

 experiment stations or the federal Department of Agriculture 

 have not always been comparable, as the same name has been 

 used to refer to widely different varieties. More dependable results 

 can only be obtained by the adoption of uniform variety names. 



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