Use of Spontaneous Mutations in Sorghum 



J. R. QUINBY 



Texas Agricultural Experiment Station, Substation No. 12, Chillicothe, Texas 



Sorghum in the United States is separated by usage into grain 

 sorghum, dual-purpose sorghum, sweet sorghum, sudangrass, 

 and broomcorn. Statistics on world production of sorghum are 

 inadequate, but the total area devoted to the crop for grain pro- 

 duction is thought to be more than 80 million acres. Sorghum is 

 grown on all the continents below latitudes of 45 degrees and 

 on many of the islands of the East and West Indies. Sorghum is 

 the chief food grain in parts of Africa, India, and China. As a world 

 food grain, sorghum ranks third, being exceeded only by rice and 

 wheat. 



In the United States, sorghum is used for human food only as 

 sorghum sirup, dextrose, starch, and oil. As a grain crop, sorghum 

 is exceeded in production only by wheat and corn and has been 

 grown on over 20 million acres in recent years. The sorghum crop 

 is now about one fifth as large as the corn crop, whereas 10 years 

 ago it was about one tenth as large. Prior to 1942, the acreage har- 

 vested for forage exceeded that harvested for grain, but since that 

 time the reverse has been true. 



Sorghum, Sorghum vulgare Pers., is a large grass of many vari- 

 eties that probably originated in Africa and has been cultivated 

 since ancient times. An Assyrian ruin dating from 700 B. C. con- 

 tains a carving depicting sorghum. In the United States, where 

 the species was introduced, as many as 400 varieties have existed, 

 many of which are sweet sorghums or sorgos. The number of varie- 

 ties grown on farms has shrunk rapidly as horses and mules have 

 disappeared from farms. It has become a cash grain crop and hybrids 

 have appeared. In Africa and Asia, numerous other varieties exist. 



These varieties, even including sudangrass [var. sudanesis 

 (Piper) (Hitch.)], cross-pollinate readily and produce fertile off- 

 spring. Vinall, et al. (43) 1 have considered all varieties as belong- 

 ing to the same species, but Snowden (35) has classified some 3,000 



'See References, page 202. 



183 



