PLANT BREEDING 643 



crook, acclimatization will come to his aid and help him to 

 preserve it. 



Of one fact we may be well assured, namely, that every plant 

 is at its best under optimum conditions. That is the time when 

 favorable variations may be most confidently expected ; in other 

 words, that is the time when it will respond most favorably to 

 selection. The writer believes this to be the general principle 

 from which to work out the conditions under which the particular 

 strain or strains yield best results, but the plant breeder must 

 not deceive himself into thinking that he will get valuable devi- 

 ations from type while the plant is enduring hard conditions, the 

 effect of which is to bring everything to the dead level of medi- 

 ocrity, where little improvement is possible by breeding without 

 first improving the conditions of growth. 



SECTION III SYSTEMS OF PLANTING 



In general, three systems of planting are in use among plant 

 breeders : 



1. The nursery system, in which the plants are treated as 

 individuals, each being given abundance of room, and each made 

 the basis of selection at the close of the season. 



2. The field system, in which individual plants are not given 

 special opportunities. Seed is saved from the best plants, but 

 no attempt is made to identify and isolate particular parentage. 

 This is " improvement " rather than breeding, and is in common 

 use among general farmers. 



3. What Webber calls the Burbank method of crowding 

 thousands of seedlings close together on good soil and then 

 selecting the few that are able to endure the battle and survive. 



Each system has its advantages, especially the first and third, 

 but the third merges into the first the moment that really close 

 work begins. 



All things considered, it is altogether likely that the greater 

 part of our results will be obtained by the so-called nursery 

 method. In any event this is the method that lends itself to 

 the best grade of work and to the most complete records. It is 

 the one therefore that will receive further consideration here. 



