200 MUTATION AND PLANT BREEDING 



the genetic constitution of the plant with respect to two plant 

 color genes, Q and P. Plants with black glumes (QP) have blackish 

 brown spots, those with red glumes (qP) have reddish black spots, 

 and those with sienna (qp) or mahogany glumes (Qp) have tan 

 spots. The pigment in the spots is water-soluble and tan spots are 

 the least objectionable in starch manufacture by the wet milling 

 method. The beautiful sienna glume color of Sweet sudanurass 

 is the result of the variety being recessive for both q and p. 



Two kinds of starch are found in varieties of many cereals, 

 including rice, maize, millet, coix, barley, and sorghum. Waxy 

 starch, which stains red with iodine, is amylopectin, a branched 

 glucose polymer. Common starch that stains blue with iodine is a 

 mixture of amylopectin along with an unbranched or linear poly- 

 mer, amylose. The properties of waxy starch make it of particular 

 interest to industry as it forms a clear paste which has little tendency 

 to gel on standing. Extensive studies of the chemical properties of 

 sorghum grain and of the properties of sorghum starch have been 

 made by Barham, et al. (3). 



Waxy endosperm of sorghum was first reported by Meyer 

 (22). Karper (12) found waxy to be a simple recessive to starchy 

 in segregating populations. Waxy varieties and hybrids are in com- 

 mercial production. The waxy allele is present in Black Amber, 

 the first sorghum to become established after being introduced into 

 the United States. The waxy allele bred into waxy grain sorghums 

 came from the Batad variety that came from the Philippines. Seeds 

 of a number of varieties from India and several kaoliangs are also 

 waxy. 



A sugary endosperm character in sorghum resembles sugary 

 in maize. The character occurs in a number of Indian varieties 

 and the sugary allele was found as a mutation at Chillicothe (31). 

 Ayyangar, et al. (1) found sugary to be a simple recessive. Sugary- 

 varieties in India have "dimpled" grains. An analysis of sugary 

 grains in India showed the amount of reducing sugars to be three 

 times the quantity found in nondimpled grains, the nonreducing 

 sugars being equal in both. No commercial use has been made of this 

 character in the United States. In India, sugary grain sorghum 

 is parched by placing green heads in beds of coals. The grain is 

 then knocked from the heads and eaten. 



