HERITABLE CHARACTERS OF MAIZE 



VIII. WHITE SHEATHS 



J. H. Kkmptox 

 Bureau Plant Industry, U. S. Department of Agriculture 



WHITIC sheath is a variation in 

 which the leaf-sheaths and husks 

 fail to (le\'elop chlorophyll and 

 remain white. The line of demarcation 

 between the sheath and the blade 

 usually is pronounced, though in ex- 

 treme cases the white area invades the 

 base of the blade, extending a few cm. 

 on both sides of the midrib. In general, 

 however, it is a characteristic confined 

 to sheaths and husks. 



The character varies not only in the 

 degree of whiteness but also in the loca- 

 tion of the first w'hite sheath. In the 

 most pronounced cases the fourth 

 sheath is the first to exhibit the lack of 

 chlorophyll while in other individuals 

 as many as ele\'en normal green sheaths 

 are prcxluced before the appearance of 

 the white ones. Five progenies which 

 breed true for the white sheath charac- 

 ter have been isolated and in these proge- 

 nies there is a tendency to develop a 

 red pigment in the sheaths after a few 

 weeks exposure. This coloring probably 

 in no way is attributable to the lack of 

 chlorophyll, and appears equalh' in- 

 tense in both the white and normal 

 green sheaths, though naturally more 

 conspicuous on the former. 



STRIKIXC; AS ORNAMHXTAL PLANTS 



Plants which de\elop the white 

 sheath character early and to a marked 

 degree are \'ery striking and like the 

 Jap(^nica striped strains may be of 

 value as ornamentals. The most ex- 

 treme strain that has been isolated 

 shows the character to be detrimental 

 to vigorous growth, although no reduc- 

 tion in vigor is noticeable in plants of 

 moderate whiteness. 



A IIKRITABLK CHARACTKR 



The character appeared simultane- 

 ously in two sister progenies of a 

 Pawnee variety, the original ear of 

 which was obtained from M. R. (iil- 



more of Lincoln, Nebraska. These 

 progenies were the result of self-pol- 

 linating the original strain for two 

 years. In both progenies the number 

 of plants with white sheaths indicated 

 that the character was a simple Men- 

 delian recessive, the actual counts 

 being 29 green 11 white sheaths and 30 

 green, 12 white sheaths respectively. 

 The two progenies, however, differed 

 markedly in the degree of whiteness, 

 one having the color of the sheaths and 

 blades sharply contrasted while in the 

 other the sheaths were noticeably 

 greenish. Indi\idual plants in both 

 progenies \aried in the degree of 

 whiteness and subsequent progenies 

 show the differences to be heritable. 



Self-pollinated seed from white 

 sheath plants produced onl\- plants 

 with white sheaths but self-pollinated 

 sister green plants or green plants from 

 sister progenies do not gi\e uniformly 

 Mendelian ratios. This is shown in 

 Table I, where the progenies of self- 

 pollinated green plants are classified. 



Tahlk I: Classification of the progenies of self- 

 pollinated fireen plants which produced some 

 plants with white sheaths. The first four progenies 

 are descended directly from the strains in which 

 the while sheaths first appeared while the others 

 are from sister progenies. 



The deficiency, from the standpoint 

 of a simple Mendelian character, of 



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