Gaines and Stevenson: Rye-Wheat Hybrids 



89 



inherited from the rye as a unit char- 

 acter, as the ratio for each is as close 

 to 3:1 as could be expected with the 

 small number of plants. The data for 

 these characters are given in the fol- 

 lowing tabulation: 



11 pubescent peduncles 4 glabrous peduncles 



12 hollow culms 3 solid culms 



Figure 18 shows Turkey and Rosen 

 with two of the F2 segregates between. 

 Ntnnber 2 represents a head from a 

 smutted plant and number 3 one of the 

 partly sterile beardless types. Figure 20 

 shows a representative head from each 

 of the Fo types. 



BUNT ON RYE 



Bunt was found this past season on 

 Common rye, on an Fo plant of Rosen 

 X Hybrid 128 and on an F2 plant of 

 Turkey X Rosen. It is a common pest 

 in this country but its attacks were 

 thought to be limited to the genus 

 Triticum. The occurrence of a totally 

 bunted plant in each of the F2 genera- 

 tions seemed to indicate the genetic 

 relationship of the parents, but when 

 later in the season two totally bunted 

 heads of common rye were discovered 

 in the variety test plots this hypothesis 

 did not seem quite so conclusive. 



DISCUSSION AND SUMMARY 



Generic crosses are fairly common in 

 the literature and many show a con- 

 siderable degree of fertility. Wheat 

 and rye are considered on the border- 

 land, representing the widest cross 

 among cereals that may be made and 

 yet recover fixed segregates in later 

 generations. In fact, it is questionable 

 whether truly intermediate segregates 

 can be so obtained, for all the wheat- 

 rye hybrids reported thus far have been 

 decidedly wheat-like by the time they 

 reached the homozygous conditions of 

 their principal taxonomic characters. 

 Similarly, the rye-wheat crosses re- 

 ported herein are all rye-like in the F2, 

 and it may reasonably be supposed that 

 the variations in subsequent generations 

 will be in the direction of the maternal 

 rye progenitor. Rosen rye seems so 



much more compatible in crossing with 

 wheat than other varieties that the 

 question arises as to whether it may not 

 carry a different complement of chromo- 

 somes. We have been able to cross it 

 with Jenkin, Hybrid 128 and Jones 

 Fife wheat and to obtain Fi plants that 

 were not entirely sterile even when 

 Rosen rye was the female parent. This 

 is a feat never accomplished with any 

 other rye at this station and is the first 

 recorded instance of a rye-wheat cross 

 insofar as the writers are aware. From 

 the three crosses 7, 143 and 27, F2 

 plants respectively were produced in 

 the season of 1921. They were all rye- 

 like in appearance resembling the 

 maternal parent strongly, and a few of 

 them exhibited as high a degree of 

 fertility as Rosen rye. 



One wheat-rye cross was obtained 

 with Turkey wheat as the female 

 parent and Rosen rye as the male 

 parent. The Rosen pollen did not 

 stamp the rye characteristics on the 

 Fi, or F2 progeny to any great extent, 

 but the abnormality and barrenness of 

 the plants showed a violent upsetting 

 of normal metabolism. The four 

 wheats used in the crosses with Rosen 

 rye are all fertile inter se. The wheat- 

 rye cross gave progeny which were all 

 wheat-like. The rye-wheat crosses 

 gave progeny that were all rye-like. 

 Thus in every case only matroclinous 

 hybrids were obtained. Although re- 

 ciprocal crosses with the same wheat 

 variety were not obtained, it seems, 

 reasoning from analogy, that if such 

 had been secured they would have been 

 very different. This is very unusual 

 and may have a cytological basis, for 

 the wheats according to Sax^ have 21 

 chromosomes (haploid) and Rosen 

 probably has 7. 



Turkey is very resistant to bunt, 

 seldom producing more than five per- 

 cent of bunted heads even when the 

 seed is blackened with viable spores. 

 The occurrence of a completely bunted 

 plant in the F2 generation of Turkey X 

 Rosen, therefore, came as a surprise for 

 it would scarcely have been expected 



*Sax, Karl. 1921. Chromosome relationships in wheat. Scisnce N. S. 54: 413-415. 



