METHODS OF BREEDING SMALL GRAINS 117 



Clausen, 1918) and is now being tried by other investigators. It 

 consists of growing a bulk plot of the cross for several generations. 

 At the end of from six to ten years, head selections may be made 

 with the knowledge that a large part of these selections will breed 

 true. The adoption of this plan will in a large measure do away 

 with the technic of studying individual plants in a heterozygous 

 population. It is desirable for those workers who would like to 

 use crossing methods but who do not have time for individual 

 plant studies. It is not so rapid as the Mendelian method. 



Technic of Harvesting, Thrashing, Etc. Slight variations in 

 methods are used by different workers. At Cornell rows of 

 like kind are taken to the thrashing shed and hung head down 

 until thrashed. At the Minnesota Station the straw is cut near 

 the base, the bundles tied with the stake, label near the bottom, 

 and the heads wrapped with a cheese-cloth covering. Bundles of 

 the same selection are then tied upright to a stake and later taken 

 to the thrashing shed when needed. The row trials at the sub- 

 stations are harvested by cutting off the heads. These are then 

 put into cloth sacks and shipped to the Central Station. 



Several machines which can be cleaned easily have been devised 

 for thrashing. The chief requisites of a machine to be used for 

 experimental purposes are that it be easily cleaned and that so far 

 as possible there be no ledges or ridges upon which seeds may 

 lodge. The alternate thrashing of different nursery crops is a 

 desirable procedure. Each of the plots of one strain of wheat may 

 be thrashed separately in rotation and then a strain of oats may 

 be thrashed in the same way. At the Minnesota Experiment 

 Station winter wheat is thrashed alternately with barley and 

 spring wheat with oats. This plan helps materially to reduce 

 the roguing of accidental mixtures from the plots. 



Various machines have been made to assist in individual head 

 and plant thrashing. A machine constructed by H. W. Teeter, 

 of the Department of Plant Breeding at Cornell (Love and 

 Craig, 1918a), is very satisfactory. As no screen or fan is used, 

 all seeds are saved. After thrashing, the seed is passed through 

 a wind blast. This machine is so arranged that mixtures may 

 be avoided. 



