212 MINNESOTA STATE HORTICULTURAL SOCIETY. 



Improvement of Vegetable Varieties by Selection. 



RICHARD WELLINGTON, ASST. HORTICULTURIST, UNIVERSITY FARM. 



In order to obviate any misunderstanding it is well to define 

 at the outset the word "variety" as it is commonly used and to 

 discuss its status in the light of modern plant breeding. Bio- 

 logically speaking, it is "an individual or group of individuals of 

 a species differing from the rest in some one or more of the char- 

 acteristics typical of the species, and capable either of perpetu- 

 ating itself for a period or of being perpetuated by artificial 

 means." According to this conception a variety is an entity in 

 itself, that is, all individuals within a variety possess identical 

 transmissible characteristics. Unfortunately this is not the case, 

 as many investigators, as well as practical growers, have proven. 

 However, this knowledge furnishes us a working basis to carry 

 on selection experiments. 



The methods of improving varieties by selection must neces- 

 sarily depend directly upon the three methods of propagation, 

 namely, asexual, cross-fertilization and self-fertilization. 



Asexual plants are those which are not propagated in a 

 sexual manner, such as the potato. Theoretically speaking, no 

 deterioration, or running out, should take place where this kind 

 of propagation is practiced, but practically it does, as plants be- 

 come diseased and decrepit by various causes and transmit their 

 weaknesses to their progeny. When degeneration in potato vari- 

 eties takes place rapidly, as it does at University Farm, prob- 

 ably due to adverse soil conditions, no amount of selection, as has 

 been conclusively proven, will bring them back to their normal 

 state. Such being the case, it is necessary to secure new seed 

 each year to obtain the maximum results. On the other hand, if 

 degeneration takes place slowly then it is advisable to eliminate 

 the weak plants and save only the strong ones, and in this way the 

 general field yield may be increased. 



Cross-fertilized plants are those whose flowers are so con- 

 structed that either insects or wind can easily distribute the 

 pollen. Examples of these are the squash, pumpkin, melon, 

 cucumber, lettuce, onion, corn, cabbage, cauliflower, radish, etc. 

 Naturally on account of this crossing many weak strains are pre- 

 served by the stronger. Corn is one of the best illustrations of 

 this phenomenon, as many experiments have proven conclusively. 

 By self-fertilizing individual plants and by breeding up strains 

 from these many are found to be poor yielders and others good 



