172 FIELD CROPS 



217. Crossing. Since wheat plants are close-fertilized, 

 crossing artificially is often practiced. To do this, the 

 unopened anthers are removed from the florets and the head 

 is covered for a couple of days until the stigmas are ready 

 to be fertilized. Ripe pollen is then taken from another head 

 and dusted on the stigmas of the head from which the anthers 

 are removed. The head is again covered to prevent any 

 other pollen from reaching it. Because of the fact that 

 wheat is not naturally cross-pollinated, crossing in this way 

 causes a great variation in the resulting plants. The crossing 

 of two varieties of wheat may bring forth plants similar to 

 either parent and many variations from either of the original 

 types, as for example, bearded wheats may result from a 

 cross between beardless varieties. The object of crossing 

 is sometimes to unite desirable characters in two varieties, 

 and sometimes to cause a greater variation than is common, 

 with a view to having greater opportunity for selection. It 

 takes several generations to fix the character of a wheat plant 

 produced by crossing. A few desirable varieties of wheat 

 have been produced in this way, but by far the greater num- 

 ber are the result of straight selection. 



218. Judging Wheat. For the purpose of judging seed 

 wheat, the agricultural colleges have devised score cards 

 giving varying values to the important points desired in it. 

 While these colleges do not all agree as to the rela- 

 tive importance of each point, they do agree quite uniformly 

 on the important points. Any of these cards will serve the 

 purpose of calling attention to the important points that 

 must be considered in judging. The following score card 

 used by the Minnesota College of Agriculture is submitted 

 as a fair sample. 



