CHAPTER XII 

 PLANT BREEDING 



164. The basis of plant breeding. It is the business of the 

 professional plant breeder to discover or originate desirable 

 varieties of plants and then to perpetuate them. As soon 

 as he becomes certain that he has obtained a really valuable 

 new variety, he proceeds to multiply it until he can offer to 

 growers everywhere its seeds, bulbs, or other means of repro- 

 ducing it. 



The possibility of producing new varieties rests largely 

 upon two highly important facts : 



1. That all the higher plants vary from generation to 

 generation. 



2. That the higher plants sometimes mutate. 



Variations are familiar enough to every observing person. No 

 two corn plants, bean plants, or tomato plants are just alike, 

 even though they may have been grown from seed from the 

 same ear, the same bean pod, or the same tomato. The varia- 

 tions may be noticed in the root, stem, leaf, flower, or fruit, 

 or in several or all of these. The term mutation is less com- 

 monly used than the term variation. It is the scientific name 

 for the kind of abrupt appearances of forms, extremely unlike 

 the parent, long known to horticulturists as sports. A single 

 bud upon a peach' tree may mutate and produce a branch which 

 will bear nectarines, and a bud upon a tree which bore purple 

 plums has been observed to grow into a branch which bore 

 only yellow plums of a kind previously unknown. Some of 

 the most valuable varieties of the grains are seed sports, or 

 mutations first noticed in the seedling grown from the seed 

 of a very different variety. 



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