Plant Breeding 



277 



Univ. of Wis. Agrtc. Expt. Sta. 



Fig. 175. The rows of cabbage at the right were grown from seed from resistant stock. 

 They have inherited the power of the parent plants to resist the disease. The plants on 

 the left are from ordinary seed. 



Successful disease-resistant plants have been discovered and 

 bred among cabbage, tomatoes, asparagus, potatoes, cowpeas, 

 flax, wheat, and cotton. 



The basis of breeding. Plant breeding with these purposes in 

 view is possible and profitable because (i) variations naturally 

 occur among plants ; (2) some variations are inherited and may 

 be preserved by selection and propagation ; and (3) different 

 varieties and species may be crossed, producing hybrids having 

 a still larger range of variations than the parent plants, or possess- 

 ing new combinations of desirable qualities which may be selected 

 and preserved. 



The methods used by the plant breeder depend upon the repro- 

 ductive structures and habits of the particular plants with which 

 he is working. For example, the means by which a plant is 

 naturally pollinated will determine how it must be handled at 

 the time of flowering to secure self-pollinated seed or cross- 

 pollinated seed. 



Plants like wheat self-polHnate naturally. A particular variety 

 may, therefore, be readily kept pure; and the seeds produced come 



