HERITABLE CHARACTERS OF MAIZE 



XVI— Dead Leaf Margins 



J. H. Kempton 

 U. S. Department of Ayrieidture, IWish'nujtou, D. C. 



DEAD leaf-margins is a charac- between the Stowell's Evergreen va- 

 ter which becomes noticeable riety of sweet corn and a dent variety 

 about the time the tassel ap- from Southern Texas known as 

 pears, but before the flowers are Brownsville. The hybrid was made 

 mature. It affects the upper six to at Victoria. Texas, in 1912 by J. H. 

 eig-ht blades usually embracing a leaf Kinsler to develop a worm-resistent 

 or two below the ear node. The dead sweet corn.' Numerous lines of this 

 band varies in width from two to original hybrid have been grown and 

 twelve mm., often wider at or near the present is one of a number in- 

 the base of the leaf, depending upon eluded for the study of various ab- 

 the intensity of expression. It is very normal forms. Crosses have been 

 conspicuous at flowering time when made between plants showing the 

 the leaves are fresh and green, but dead margin character and ten or fif- 

 notwithstanding- this fact was not teen other well-known aberrant forms, 

 noted until through chance a homo- From the behavior of these crosses it 

 zygous progeny was grown. seems that in addition to the character 

 The leaves of most normal corn dead margins the progeny is aft'ected 

 plants if allowed to dry usually wither with some lethal factor as many of 

 first at the tips, the whole process the hybrid seeds fail to grow. Four 

 being gradual, though it follows from hybrids, however, were grown suc- 

 the shape and structure of the leaf cessfully and all had normal leaves in 

 that the tissue dries more rapidly the first generation while in the see- 

 along the margins than along the ond generation dead leaf margins re- 

 midrib. However, with some plants appeared in approximately twenty-five 

 the leaf margins are the first to wither per cent of the plants, though with a 

 and the blade gradually dries toward wide range in variability which re- 

 the midrib. The leaves of the varia- duces the reliability of classification, 

 tion dead margins would be confused The classes for all four hvbrids were 

 readily with this latter form of dry- 440 normal. 138 dead margins, the 

 ing, especially if seen late in the sea- percentage of dead margins being 

 son, but the dead margmal tissue of 23.9 1 1.2. From the nature of the 

 the variation is api)arent when the character the plants must be classified 

 plant IS at its maximum vigor and ^^ ^^ ^^^^^^^ flowering time so that 



there should be no uncertainty if the 

 plants are examined at the time of 

 flowering. 



The strain now designated dead leaf 

 margins was noted as a homozygous 

 progeny in 1920. Its ancestry for five 

 generations is known, but only the 



the character dead margins will not 

 be confused with the natural death of 

 the leaves. 



From an analysis of small progenies 

 dead margins seems to be unrelated 

 genetically to brachytic culms, ramose 



two generations preceding 1920 were inflorescence, sweet endosperm, sun red 



the result of self-pollination, the plant color, two factors for lineate 



others being crosses between sibs. leaves, and a chlorophyll disorder, vel- 



The strain is descended from a hybrid low leaf spot. 



^Breeding Sweet Corn Resistant to the Corn-Ear Worm. Collins, G. N. and J. H. 

 Kempton. Jour. Agri. Research. Vol. XI, No. 11, pp. 549-572. December 10, 1917. 



349 



