FERTILE WHEAT-RYE HYBRIDS' 



Crosses Between Wheat and Rye Are Usually Sterile — A Fertile Cross May Have 

 the Good Qualities of Wheat and the Hardiness of Rye 



H. H. Love and W. T. Craig 



{In Cooperation with the Office of Cereal Investigations, U. S. Department of 



Agriculture) 



AT VARIOUS times crosses have 

 been made between wheat and 

 rye. One of the earliest to report 

 was Wilson (1) who was followed 

 by Carman (2), Rimpau (3) and others, 

 namely, Signa (4), Schliephacke (5), 

 Miczynski (6), Nakao (7), and Tscher- 

 mak (8). The result of most of the 

 crosses was that the hybrid plant 

 was sterile. Only Miczynski, Carman 

 and Rimpau obtained fertile hybrids. 

 Later we have the work of Jesenko (9), 

 Leighty (10) and McFadden (11). The 

 latter reports the result of a wheat-rye 

 cross which was sterile. Leighty re- 

 views the work of Carman and later 

 gives some of his own work where he 

 produced wheat-rye hybrids artificially 

 and also found some natural hybrids 

 between wheat and rye. 



Jesenko reports upon what seemed a 

 fertile wheat-rye hybrid but, as a result 

 of further investigation, concluded that 

 what he supposed was a fertile hybrid 

 was really the result of a backcross 

 between the Fi and wheat. He also 

 believed that the fertile hybrids ob- 

 tained by Rimpau and Miczynski were 

 the result of backcrossing with wheat 

 and not the result of self-fertilization. 

 Jesenko backcrossed very many Fi 

 flowers with both wheat and rye. When 

 he used wheat he obtained about three 

 seed per thousand flowers pollinated, 

 and with rye he obtained only one seed 

 from 4,800 flowers pollinated. When 

 the Fi was backcrossed with wheat the 

 resulting Fo plants were very similar 

 to wheat, and the result when rye was 

 used was a plant very similar to rye. 



Jesenko suggests that it is possible 

 that in the egg cells the amount of 

 wheat and rye plasm is not equall}^ dis- 

 tributed but that sometimes more wheat 

 and, again, more rye plasm is present. 

 Then, when a pollen grain from a wheat 

 plant would fertilize an egg cell with 

 little rye plasm and nearly all wheat, a 

 plant similar to wheat would be ob- 

 tained. This plant would be fertile. 

 As the rye plasm is increased, in the 

 egg cells the plant developing will 

 be less wheat-like and less fertile. This 

 would continue until complete sterility 

 would be obtained. The reverse would 

 be true if a pollen grain from rye would 

 fertilize an egg cell containing more rye 

 plasm than wheat. The plant would 

 be fertile and more like rye. As the 

 rye plasm decreases and the wheat plasm 

 increases the resulting plant would look 

 less like rye and would be less fer- 

 tile until complete sterility would be 

 reached. 



A SUCCESSFUL CROSS 



A number of crosses between wheat 

 and rye have been made by the authors. 

 Most of these have been sterile in Fi and 

 no attempts were made to cross them 

 back with wheat or rye. So far as the 

 characters of these hybrids are con- 

 cerned , they agree with the results usu- 

 ally obtained when this cross is made, in 

 that the hybrid is intermediate in many 

 respects. Two hybrids between wheat 

 and rye have been fertile, and it is 

 planned to describe here briefly the 

 results obtained, so far, from one of 

 these crosses. 



'Paper No. 76, Department of Plant Breeding, Cornell University, Ithaca, N. Y. 



195 



