quinby: mutations in sorghums 185 



bia in 1879. The variety was called "Millo Maize" (14). How Black- 

 hull Kafir reached the United States is unknown (43), but the varie- 

 ty was growing on farms in Kansas about 1890. A late-maturing 

 kafir was introduced from Columbia in 1880 (14) and was distributed 

 in South Carolina as "White Millo Maize". Perhaps Blackhull 

 Kafir originated as an early-maturing mutation in this late-matur- 

 ing kafir. White Kafir and Red Kafir from Natal were shown at the 

 Centennial Exposition at Philadelphia in 1876 and seed from the 

 exhibit was later distributed. Pink Kafir, Feterita, Hegari, and 

 Sundangrass were introduced in 1904, 1906, 1908, and 1909, respec- 

 tively. Broomcorn has been grown in the United States since Ben- 

 jamin Franklin began its culture with seeds plucked from an 

 imported broom. 



Transformation of Sorghum in the United States 



The mechanization of agriculture and changes in sorghum 

 that began about 30 years ago have changed sorghum from a feed 

 crop for use on the farm into a cash grain crop. The chief changes 

 in sorghum on the farm since 1930 have been a reduction of about 

 40 centimeters in height and a shortening of the duration of growth 

 by about a week. The reduction in height and dry-headedness asso- 

 ciated with early maturity have made combine harvesting possible. 

 Sorghum production has expanded into higher latitudes and higher 

 elevations as extremely early-maturing varieties have become avail- 

 able. Recently, a method of hybrid sorghum seed production using 

 cytoplasmic male-sterility has been devised and hybrids have resulted 

 in an expansion of acreage in areas outside the "sorghum belt" as 

 well as within it because of higher yields. 



These changes have come about from making use of alleles 

 discovered in the species. The transformation of sorghum in the 

 United States within the last half century is actually a further domes- 

 tication of the species to make it fit the needs of mechanized farm- 

 ing. Most improvement in sorghum has resulted from accumulating 

 desirable alleles in a single variety. 



Genes Used in Sorghum Improvement 



Many of the contrasting characters present in sorghum were 

 in one or another of the varieties introduced into the United States, 



