36 



APPLICATION OF PRINCIPLES TO FARM CROPS 



Cross-Pollinated 

 Plants. The problem of 

 improving plants belong- 

 ing to this group is much 

 more difficult. There is 

 always the danger that 

 they will be mixed with 

 other seeds or individuals 

 through the distribution 

 of pollen by wind and 

 insects. Corn, cotton, 

 timothy and rye are im- 

 portant farm crops be- 

 longing to this group. 

 Little can be done by the 

 ordinary farmer in im- 

 proving such crops. The 

 careful breeder devoting 

 his entire time to the 



work may succeed in establishing improved varieties. 



Note the great effect of extreme crosses as shown in figure 27. 

 Corn Breeding. The corn plant bears the pollen in the tassel 



and the pistils are located on the young ear. The ovule is attached 



FIG. 25. Wheat breeding in Minnesota. Each 

 trial plot is easily kept pure because the plant does 

 not cross-pollinate, but the ripening seed must be 

 kept from shattering and also protected from spar- 

 rows by tying the heads as shown. Accurate tests 

 are then possible. (Minnesota Station.) 



FIG. 26. The methods involved in breeding wheat are very tedious. After the flowers 

 are artificially cross-pollinated they are protected with bags and properly labeled and records 

 are kept of both parents so the pedigree of all the seeds will be known. (U. S. D. A.) 



