Aug. 26,1918 
Variation and Correlation in Wheat 
363 
Williams and Welton (1913) compared the yields for a period of 5 
years from large and small seed oats separated by a fanning mill and 
sown at both a uniform rate in pounds per acre and at a varied rate, the 
aim of which was to secure the same number of plants per acre. The 
large seed exceeded the small in yield at both rates of seeding by approxi¬ 
mately 4 bushels per acre. The experiment was continued by using 
large and small seed compared with seed as it came from the threshing 
machine. The 4-year results show no advantage in favor of the he’avy 
over the ungraded seed at either rate of seeding. At the uniform rate 
of seeding the small seed was as efficient as either of the two other grades, 
but at the varied rate it produced 2 bushels less per acre. A comparison 
was also made of hand-selected primary and secondary kernels of oats 
definitely spaced. In 3 out of the 5 years the primary seeds proved 
more efficient. 
In a more recent experiment Williams (. 1916 ) made a comparison in 
field trials for 8 years of large, small, and unscreened seed of winter 
wheat with no advantage of large over either of the two other grades. 
A 6-year trial of hand-selected, large and small seeds from pure lines of 
wheat showed an advantage in yield of 48 per cent in favor of the former. 
Georgeson, Burtis, and Otis {1897) in an 8-year trial of three grades 
of seed oats, heavy, light, and unscreened, found the heavy seed more 
efficient than unscreened seed by 1 bushel and more efficient than the 
light seed by 3 bushels per acre. 
In an earlier bulletin Georgeson, Burtis, and Otis ( 1896 ) report the 
results of a 6-year trial of heavy, light, and unscreened wheat. The 
heavy and unscreened seed gave practically the same yields, which were 
superior to the yields from the light seed by C/s and 1 1 / 2 bushels, respec¬ 
tively. 
Zavitz (1915) reports the results of six trials with hand-selected, large 
and small seeds of four varieties of oats grown at seven distances apart. 
In 90 per cent of the trials the large seeds proved superior. In another 
trial, covering a period of from 3 to 9 years, hand-selected, large, plump 
seed yielded in oats 15.4 bushels, in barley 10.6 bushels, in spring wheat 
5 bushels, and in winter wheat 6.5 bushels per acre more than small, 
plump seed of the same variety. Large, plump seed in oats proved 
more efficient by 7.9 bushels per acre than medium-sized plump seeds. 
METHODS OF EXPERIMENTATION 
The soil on which our plants were grown is classified by the United 
States Soil Survey as Hempstead silt loam. The rotation followed on 
the field where the plants were grown in 1914 and 1915 was as follows: 
Spring rye, clover, grain, com with 14 tons 6f manure per acre, field 
peas, roots, and spring wheat. The soil is in a moderately high state of 
fertility. In 1916 and 1917 the plants were grown in a grain-dover-corn 
rotation, with 6 tons of manure applied preceding the com. The soil is 
