Harlan and Pope: Dwarf Barley 



273 



1921 the Aberdeen "dwarfs" were again 

 typical of the dwarf plants as grown 

 outdoors in summer. One of these had 

 26 culms about 60 cm. long and having 

 12-18 nodes, and on the same plant 

 were found 5 culms which seemed 

 normal. None of the latter possessed 

 more than 6 nodes above the crown, 

 the longest was 92 cm. in height, and 

 all five had nearly normal spikes. 



The crosses were made in 1920 upon 

 4 varieties, as shown in Table I. 



The crossed seed was grown in the 

 greenhouse at Arlington Farm in the 

 following winter and the Fi heads 

 shown in Figure 15 were obtained. 

 No "dwarf" characteristics were found 

 in the plants bearing these heads. The 

 Fo seeds from these heads were sown 

 at Aberdeen in 1921 and produced 

 populations which segregated for type 

 of plant as shown in Table II. 



In the Utah Winter cross, the winter 

 plants cannot be accurately classified 

 because of late maturity. Considering 

 the small numbers used, the ratios 

 obtained are in fair accordance with 

 the expectation on a basis of a 3:1 

 ratio, showing the segregation of a 

 Mendelian recessive. 



Few dwarf plants have been re- 

 ported in barley. Bungo Miyazama^ 

 reports the finding of dwarf forms 

 in the back-cross upon Golden Melon 

 by an Fi plant, the offspring of a cross 



between Golden Melon and the Japan- 

 ese variety, Sekitori. This dwarf was 

 heterozygous, breaking up into normals 

 of the parental types and a still more 

 dwarfed type in the ratio of 1:2:1. 

 Neither of these dwarfs was at all like 

 the one here discussed. Vestergaard^ 

 reports finding 3 dwarf-like variants in 

 an otherwise constant line of 2-rowed 

 barley. When crossed with Binder 

 barley, of the 95 individuals, con- 

 stituting the F2 progeny, 81 were 

 normal and 14 dwarf, giving a ratio of 

 6:1. The dwarf is not described. 



In February, 1922, Dr. K. F. Keller- 

 man, Associate Chief of the Bureau of 

 Plant Industry, called the attention of 

 the writers to a dwarf form of Hordeum 

 vulgare pallidum which he had received 

 from Mr. J. M. Mack of Fallbrook, Cal. 

 Mr. Mack stated that he had discov- 

 ered the type in a field two years 

 previously. This dwarf is apparently 

 the same type of variation as that 

 found by the writers, but in a 6-rowed 

 hulled barley, while that found at 

 Aberdeen was in a 2-rowed naked 

 barley. The double appearance of this 

 variation seems to have one plausible 

 explanation, namely, that it is a muta- 

 tion where all the modifications which 

 occur in the plant are caused by the 

 same factor. 



Hor^ describes what is undoubtedly 

 the same barley as that received 

 through Dr. Kellerman. 



Table I. Data Regarding Barley Varieties Crossed with the Dwarf Form- 



Baku, 



Manchuria, 

 Utah \^'inter, 



Nepal, 



H. dis. nudum, 

 H. V. pallidum, 

 H. V. pallidum 



pyramidatum, 

 H. V. trifurcatum, 



2-ro\ved, bearded, naked (parental type of "dwarf"), 

 lax 6-rowed, hulled, bearded. 



very dense, 6-rowed, hulled, bearded, winter habit, 

 6 rowed, naked, hooded. 



* In addition to the 39 normal and 8 dwarf plants, there were 5 winter plants which could not 

 be classified. 



^ Jour. Genetics, 11:205-208, 1922. 



2 Tidssk. PlanteavL, 26:491-510, 1919. 



' Science, Vol. LV, No. 1423, April 9, 1922, 



