Improving Plants by Selection or Breeding. 551 



tunity to clearly distinguish each individual plant and determine its 

 characteristics, total yield, and the like. In recent years this method of 

 growing the individual plants at a standard distance from each other in 

 order to test their yielding capacities, and the like, has been used by 

 Professor Hays in his experiments at the Minnesota Station. Here, 

 however, a standard distance of four inches apart was used instead 

 of one foot. 



The Field method was used by Rimpau about 1867, and probably by 

 many others before that time. By this method, the selections are made 

 from plants grown under normal field conditions. The claims for this 

 method is that we can only judge what a plant will do in the field under 

 ordinary conditions of field culture, by growing and selecting it under 

 these conditions. In the large majority of cases the first selections are 

 probably made from plants grown in the field in the regular course of 

 crop production, which thus were not specially grown for the purpose. 



If one is to use the Nursery method, the plants must be especially 

 planted. While the nursery method certainly allows the breeder to dis- 

 tinguish the individual plants more clearly, in crops like wheat, oats, 

 and so on, which are sown broadcast or drilled, it entails very much extra 

 work and is probably to be recommended only for the use of experi- 

 menters who are giving their entire time to the work. 



In selecting the best plants in any crop the breeder must aim to 

 examine a very large number of plants and carefully compare their 

 important characters. To know what the important characters are, it is 

 necessary to be familiar with the crop and have a thorough knowledge 

 of those qualities which go to make up a plant of the greatest intrinsic 

 value. 



In making the first selections it- is usually the best policy to make a 

 preliminary selection of a much larger number of plants than are actually 

 desired. The breeder can then examine these selections with greater care 

 and discard the poorest from among them retaining only the superior 

 individuals. 



Careful breeders have found it very desirable to have a clearly defined 

 ideal type which they are striving to produce. In selections within the 

 race the breeder should have all of the characters of the race which he 

 is breeding clearly in mind in order to adhere strictly to the type of the 

 variety in the selections. In making selections of new variations, muta- 

 tions, etc., in attempting to secure new races, naturally no one type can 

 be adhered to. In testing these different individuals, however, the 

 characters of a certain type should be borne in mind and deviations 

 from this type in the progeny should be weeded out. 



