MAIZE BREEDING 191 



conception of inbreeding and cross-breeding as applied to corn 

 improvement. Lindstrom found, for example, that plants con- 

 taining the wW combination were less vigorous than WW 

 forms. As a rule, a Ww plant produced only a single stalk which 

 was easily blown over in a strong wind. 



There are also abnormal chlorophyll types which appear in 

 the mature plant. Of these, golden, green-striped, fine-striped, 

 and japonica types are simple Mendelian recessives to normal 

 green. In the golden type, when a month or more old, the green 

 color begins to disappear. The golden type is not very vigorous 

 toward maturity. It produces abundant pollen and small ears. 

 The green-striped form appears about two months after germina- 

 tion. These stripes are uniform in distribution, green and lighter 

 areas alternating, and running parallel through the leaf. Mature 

 green striped plants are less vigorous than normal green forms and 

 the leaves wilt more severely on hot days. The japonica types are 

 striped with green, pale yellow, yellow, and white, and are well 

 known, being frequently used for ornamental planting. These 

 forms are more vigorous than the golden or green-striped types. 

 There are- also fine-striped and spotted forms. The spotted 

 forms have not as yet been studied thoroughly. 



Four of % the mature plant chlorophyll types have been found 

 to be recessive to the normal green forms. The following 

 genetic factors have been used by Lindstrom: 



g golden type 

 st green-striped 

 j japonica 

 / fine-striped 



The following summary expresses the factorial condition of 

 these forms of chlorophyll abnormality; 



CHLOROPHYLL TYPES CHLOROPHYLL FACTORS 



Green WVLGStJF or WVlGStJF 



White wVLGStJF 



Virescent-white WvLGStJF 



Yellow WvlGStJF 



Golden WVLgStJF or W VlgSUF 



Green-striped WVLGstJF 



Japonica white-striped WVLGStjF 



Japonica yellow-striped WVlGStjF 



Fine-striped WVLGStJf 



