December, 1921. 



SCIENTIFIC AGRICULTURE. 



115 



tion of the glume ha.s nothinfr to do with 

 the colour of the grain. Tliis may not ex- 

 press the facts clearly as in the Fo genera- 

 tion a wide variation in colour is to be ob- 

 served. Thus ears with black palea may 

 contain grain which has variations of 

 black, purple or violet green in the caryop- 

 sis. These sliades may be faint, but can be 

 clas.sed as dark, if tliey show any colour 

 at all. 



Narrow glumes dominant over broad. 



With most barleys, the glumes are nar- 

 row but there are varieties with ovate lan- 

 ceolate glumes. When H. Ahyssinicum and 

 H. Steudelii or H. Ahyssi)iicum and H. 

 trifurcafum were crossed, the F^ genera- 

 tion all had narrow glumes, but in the F^ 

 and F3 generations narrow and broad 

 glumes appeared and in the ratio of 3 to 

 1. Also, the broad glumes all bred true. 



Lax ears dominant over dense ears. 



As far as can be determined, lax ears 

 are dominant over dense. In the F, genera- 

 tion, as Spillman was able to demonstrate 

 in wheat, the heterozygote is intermediate 

 between lax and dense. Cases have been re- 

 corded where the Fj was laxer than the 

 parent bearing that character. The F, has 

 contained similar lax forms. Biffin expres- 

 .ses the opinion that the characters of lax- 

 ness and denseness in the ears may be de- 

 pendent on more than one set of char- 

 acters. 



Adherent palea dominant over non- 

 adherent palea. 



In cases where the parent has naked 

 grain as it is in the w^heats, the heterozy- 

 gote seems to be rather intermediate be- 

 tween the parents. The grains rub out 

 quite freely in some, while in others con- 

 siderable difficulty is experienced in se- 

 parating the palea from the grain. From 

 experiments conducted to find out which 

 character was dominant, on counting all 

 individuals in which the palea could be 

 separated from the grain, it was found 

 that 76 could be grouped in the class in 

 which the grain could be readily separated 

 from the palea and 25 in the cloaked 

 group. Sowings made from 20 plants with 

 naked grain all bred true. Similarly, a 

 like number of plants were tested in which 

 the grain was enclosed and with 10 in 

 which the grain was more or less enclosed. 

 It was found impossible to draw a sharp 



line between these groups, as both hetero- 

 zygous and homozj'gous forms were pre- 

 sent. On further trials with similar char- 

 acters, using other varieties and pressing 

 the ba.se of the rachis below each spikelet 

 in.stead of rubbing, it was found that of 72 

 individuals so tested, 21 bore perfectly free 

 grain and in the remainder the grain was 

 more or less trapped, so that it would ap- 

 ]iear tliat tliis trapped condition comes 

 very near to being dominant over tlie naked 

 condition but due to the great difficulty of 

 separating the forms in the F, generation, 

 it is being treated at present as giving in- 

 termediate with partially naked grain. 



Brittle rachis dominant over tough rachis, 



A great many varieties of barley have 

 this character of brittleness but not in any- 

 very marked degree, with the exception of 

 H. Spontaneum. With this variety, the 

 spikelets break away as soon as they be- 

 come ripe. When this variety was crossed 

 with a six-rowed, hooded variety with more 

 or less tough rachis, as the ears ripened the 

 rachis shattered and the spikelets were set 

 free as with the parent. In the F^ genera- 

 tion, numerous types were produced, as 

 the original parents differed in several 

 features, but the brittle and tough char- 

 acter was distributed in all types. The pro- 

 portions were 06 brittles to 15 with a tough 

 rachis, or roughly 3 to 1. It was found in 

 the Fj generation, that several of the hy- 

 brids were more brittle than the original 

 parent. 



Rough awns dominant over smooth awns. 



Some varieties are known in which the 

 awns are quite smooth because of the ab- 

 sence cf the small teeth which, in most bar- 

 leys, give to the awns their disagreeably 

 tenacious character. The common form, 

 with teeth, has been found to be dominant 

 over the smooth form, the latter reappear- 

 ing in twenty-five per cent, of ^he plants 

 of the second generation. 



Awnless condition dominant over hooded. 



There has not been sufficient investiga- 

 tion on this subject as yet to give definite 

 results on the inheritance of this awnless 

 character. However, there has been a 

 cross made, involving these characters in 

 H. nigrosuhenenne and hexasticofurcatum. 

 This awnless character caused considerable 

 interest when reported by Rimpau, 



