HERITABLE CHARACTERS OF MAIZE 



VII. SHRUNKEN ENDOSPERM- 



C. B. Hutchison 

 New York State College of Agriculture, Cornell University, Ithaca, N. Y. 



determine its relation with other known 

 genetic factors. Subsequently, thru 

 the kinchiess of Dr. Emerson, all of this 

 material came into possession of the 

 writer. 



IN 1914 Professor R. A. Emerson 

 recei\e(l from Dr. M. R. Gilmore 

 of the Nebraska Historical Society 

 several small packages of maize seeds 

 which the latter had collected the 

 previous year from gardens of the 

 Ponka Indians on the Niobrara reser- 

 vation in Nebraska. Among these 

 packages was one containing starchy 

 and sugary, white, red, and purple, and 

 self-colored and speckled kernels, all 

 of which had l)een taken from a single 

 ear. These seeds were planted at the 

 Nebraska E.xperiment Station by Dr. 

 Emerson and a number of the resulting 

 plants self-pollinated. On one such 

 self-pollinated ear in this pedigree there 

 appeared among the starchy kernels 

 certain ones with an unusual type of 

 indentation. The kernels of flour corn 

 ordinariI\- are not indented at all but 

 are smooth and rounded in shape like 

 flint corn. The starchy kernels on this 

 ear were floury in texture and most of 

 them smooth and rounded. Some, 

 however, were deeply indented at the 

 top with a smooth crease or, in the case 

 of broad and thick kernels, with a deep 

 dimple. Others were indented not at 

 the top but on the sides, as if in drying 

 the endosperm had shrunken and the 

 sides of the kernel had fallen in. Still 

 others were indented at both the top 

 and sides which gave them a shrunken 

 and pinched appearance. When these 

 unusually shaped seeds were planted 

 and the resulting plants selfed, they 

 were f(»und to breed true for this 

 character and subsequent tests have 

 shown it tf) be inherited as a simple 

 recessive to the normal or full endo- 

 sperm. It has been called "shrunken" 

 and is designated by the genetic 

 symbol sh, the dominant allelomorph 

 of which is Sh. 



In 1918 shrunken was crossed with a 

 number of other types of maize to 



DESCRIPTION OF SHRUNKEN ENDOSPERM 



An adequate conception of the 

 nature and general appearance of 

 shrunken kernels ma\' best be had from 

 examination of the accompanying illus- 

 trations. In Figure 20 two selfed ears 

 from homozygous shrunken plants are 

 shown and in Figures 21 and 22 ears 

 containing both shrunken and non- 

 shrunken kernels in approximately 

 equal numbers. The latter ears are 

 the result of pollinating plants hetero- 

 zygous for the factor for shrunken 

 with pollen from homozygous shrunken 

 plants. Figures 23 and 24 show dif- 

 ferent views of shrunken and non- 

 shrunken kernels taken from the same 

 ear. 



It will be noted from Figures 21 and 

 22 that where the rows are straight and 

 the kernels fairly uniform, especially in 

 the middle portion of the ear, shrunken 

 kernels are usually more flat, somewhat 

 broader, and frequently shallower than 

 non-shrunken ones. In such kernels 

 the top is usually folded in to form a 

 deep and smooth crease altho at times 

 the indentation is from the sides of the 

 kernel giving them a pinched appear- 

 ance and lea\ing considerable space 

 between the kernels at the top. On 

 the butt or tip of the ear where the 

 kernels normalK' are irregular in shape, 

 or wlu-re adjoining kernels fail to 

 (kNeloj), shrunken kernels are char- 

 acterized 1)\- a deep, broad and rounded 

 dimi)le. 



The shrunken indentation is some- 

 times not unlike the creased or roinided 

 dimple found in ears of a flint>' type 

 of dent corn — particularly on the butt 



Paper No. 87, Department of F'hint Hrccdinj;, tOrncIl University, Ithaca, New ^■ork. 

 Photographs by \V. I. Fisher. 



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