THE SORGHUMS 377 



apparent than that produced by other forms of vegetable 

 matter. 



The evil effects of sorghum on the land are usually only 

 temporary, being most marked on the first crop following 

 and conipletely disappearing in two or three years. 



466. Fertilization and crossing. — The sorghums are 

 capable' of both self-pollination and cross-pollination. 

 They are normally self-pollinated and are not injured by 

 this process as is corn. 



As the hght pollen of sorghums is easily carried by the 

 wind, different varieties or types, when planted close to- 

 gether are subject to more or less crossing. Ball ^ found 

 that when different varieties were planted in adjacent rows 

 and flowered at the same time as high as 50 per cent of the 

 seed, produced on the leeward row was cross-fertilized. It 

 has been conclusively demonstrated that all of the different 

 types of sorghum, such as saccharine and non-saccharine 

 sorghums, and the broom-corng will intercross readily if 

 grown in close proximity t6 each other. 



467. Breeding (Figs. 63, 64). — Sorghum lends itself 

 easily to improvement by selection. The selection should 

 be made before the plants flower, and the selected plants 

 should be prevented from becoming contaminated by 

 bagging the heads before the stigmas are exposed. The 

 bags should be removed as soon as the seeds have set to 

 prevent the heads from molding. 



The producing power of the selected plants is deter- 

 mined by the head-to-row method. This method is carried 

 out in the same manner as the ear-to-row test of corn, 

 page 196, except that in the sorghum breeding-plot no pre- 

 cautions are taken to prevent inbreeding. On the^ other 

 hand, the best heads in the most productive rows are 

 '■ Ball, Carleton R., Am. Breeders' Assoc, Vol. VI, p. 193. 



