Apr. 5,1924 
Effect of Modified Hot- Water Treatment on Wheat 
83 
against injury from copper sulphate. He found that machine-threshed grain, on 
this account, was far more susceptible to treatment injury than grain threshed 
by hand. Kuhn ( 6 ), Von Tubeuf (13), Volkart (14), Burmester (2), Hurd (5), 
and others have confirmed Nobbe’s work. A test was made, therefore, to 
determine whether the physical condition of the seed coat might be an important 
factor also in connection with seed injury by the modified hot-water treatment. 
Three hand-threshed wheat varieties, grown on Arlington Experiment Farm in 
1921, were used. Four lots, each containing 100 kernels, were taken from each 
variety and prepared as follows: Lot 1, seed coats left unbroken, seed untreated; 
lot 2, seed coats left unbroken, seed treated; lot 3, seed coats slit over the embryo, 
seed untreated; lot 4, seed coats slit over the embryo, seed treated. (The seed 
coat may be slit easily with a sharply pointed needle after first immersing the 
kernels in water for several minutes.) The modified hot-water treatment was 
applied simultaneously to lots 2 and 4 on January 25, 1922, after which they 
were dried six days at room temperature. The untreated and treated seed was 
sown then in soil in the greenhouse on January 31, 1922. One month later the 
seedlings were counted. The results are presented in Table IV. 
Table IV. —Percentages of germination of hand-threshed seed of three wheat varieties 
with seed coats unbroken or broken over the embryo , untreated or treated by the modified 
hot-water method 
Percentage of germination 
Variety 
C.I. 
No. 
Seed coat unbroken 
Seed coat broken over 
embryo 
Untreated 
Treated 
Untreated 
Treated 
Fulcaster. 
3115-2 
100 
100 
100 
6a 
Dawson. 
1733 
98 
100 
98 
<±€L 
Diehl-Mediterranean. 
1395 
96 
94 
97 
3 a 
9 
Average. 
98.0 
98.0 
98.3 
4.3 
« Seedlings very small and spindling. 
As indicated in Table IV, the hot-water treatment reduced germination only 
when the seed coats were broken. The physical condition of the seed coat over 
the embryo, therefore, bears a definite and important relation to the amount of 
injury caused by the modified hot-water treatment (PI. 2). 
In many samples of machine-threshed wheat, breaks in the seed coats fre¬ 
quently were found over the endosperm only. In order to determine the effects 
of hot-water treatment on grain with seed coats in this condition, four lots of 
200 kernels each from a hand-threshed sample of the variety China (C. I. 180) 
were used. The seed coats were left unbroken in the first lot. In the second 
lot, a small slit was made in the coat about one-eighth of an inch above the top 
of the embryo. In the third lot, a small part of the seed coat was scraped away 
at the brush end of the seed. In the fourth lot, a slit was made in the seed coat 
over each cheek in a location behind the embryo. One hundred kernels of each 
of the four lots were treated simultaneously on September 4, 1922, and dried 5 
days at room temperature. The untreated and treated seed was then sown in 
soil in greenhouse flats on September 9, 1922, and the seedlings were counted 
after periods of 10, 20, and 30 days. Many which developed from the treated 
seed with the coats broken over the endosperm were very small and spindling. 
For this reason, the seedlings were recorded as either normal or abnormal at each 
of the three periods when the counts were taken. The results are presented in 
Table V. 
