Aug. 6, 1917 



Studies on Oat Breeding 



307 



toward the wild-oat parent showed a pubescence on the upper grain. 

 These atavistic regressions represent really the wild form. In similar 

 cases observed occasionally by the present writers the pubescence appears 

 not in form of tufts of hair at either side of the base, but covers the whole 

 base as in the wild oat. Finally, Fruwirth (2) observed two spikelets of 

 an oat plant in which also the upper grain had a pubescence. This char- 

 acter, however, did not prove to be heritable, as the progeny of that plant 

 did not develop it. 



In many wild oats, Avena fatua, A. sterilis, etc., a heavy pubescence is 

 developed at the base of the upper grain. In A. fatua that condition 

 appears completely correlated with other specific characters (11,6). The 

 type of pubescence in the present case, however, is different from that 

 of the upper grain in the wild oat. While in the latter case a heavy, 

 thick pubescence covers all sides of the base (6, pi. 3, fig. 6) the pubescence 

 developed at the base of the upper grain in hybrid plants of the cross in 

 question shows only two more or less thick tufts of hair at either side of 

 the base. As seen in Plate 46, C, this type of pubescence is similar to 

 that of the intermediate forms resulting from crosses between A. fatua 

 and cultivated oats. 



In order to determine the distribution of the plants with pubescence 

 on the upper grain in relation to the character of the glume, the plants 

 were grouped in three classes. The first class comprises the plants with 

 typically intermediate type of hull — that is, plants with a majority of 

 intermediately hulled lower grain and a few fully hulled. The middle 

 group represents the forms most closely approaching 'the hulled condition 

 of grain, while the third class contains only the plants with normal, firmly 

 hulled grain. Table VIII shows these three classes of plants in relation 

 to the pubescence on the upper grain. 



Table VIII. — Relation between the pubescence on upper grain and ilie hull character 



This table shows that the majority of plants with pubescence on the 

 upper grain fall into the group in which the lower grain is either naked or 

 intermediately hulled and the upper intermediately or firmly hulled. In 

 the same measure as the glume of the lower grain becomes coarser ap- 

 proaching, as in the middle group, the firmly hulled condition, the pubes- 

 cence on the upper grain tends to disappear. 



In the last group with normal, completely hulled grain none of the up- 

 per grain develops a pubescence at the base. This gradual change in 

 100302°— 17 3 



