210 MAIZE 



CHAP, obtain pure strains from mixed ones, and to propagate pure 

 strains when one has them. 



By rigid selection we avoid the production or propagation of 

 new forms ; by cross-breeding we encourage it. 



By cross-fertilization we mean crossing plants of different 

 " varieties," breeds, or races of the same species as, for instance, 

 two kinds of maize. This will be discussed more fully a little 

 farther on. 



The strict definition of the term hybridization implies 

 breeding from two parent plants belonging to different species 

 or genera as, for instance, wheat and rye. It is of little or no 

 practical importance in the improvement of farm crops, and 

 need not be further discussed here. 



165. Selection of Parents. — The first step in breeding is to 

 secure well-bred stock. This does not always mean the im- 

 portation of fresh strains, unless the latter offer decided im- 

 provement over the old ; if the breeds already acclimatized in 

 the country are satisfactory as regards breed characteristics, it 

 is sometimes better to use them as q , basis f or improvement 

 than to rely entirely on something the adaptaTbility~aTwKifeh 

 to local conditions has not been proven. As Hartley (5) 

 tersely puts it : " Under extremely difficult conditions of 

 growth, teosinte and the buffalo will thrive better than im- 

 proved types". But local strains are often so mongrel (i.e. 

 heterozygous) in character that it would take years of patient 

 toil, and much expense, to breed them pure ; in such cases we 

 must rely on the importation of fresh stocks. Whichever course 

 we follow, we must select the parents best fitted to produce the 

 desired type of offspring. 



Sheep farmers, who start with a highly-bred stud flock of 

 acclimatized animals, do not take long to build up a large flock 

 if they are good sheep farmers. But the best of them find it 

 comparatively slow work to grade up a mixed flock. So it is 

 with maize. If we can start with pure, high-bred, acclimatized 

 seed, we gain enormously in time, for all that is then necessary 

 is to maintain the purity, and continue the improvement already 

 started. But at the present time it is impossible to meet the 

 demand for pure high-bred seed, acclimatized to each maize- 

 growing district in South Africa. 



In the selection of parents care is taken that both are as 



