SEEDLING BLIGHT AND STACK-BURN OF RICE. ““t9 
TaBLE 4.—Germination of Honduras rice seeds from Louisiana treated in water at 
54° C. for 15 minutes, after presoaking 16 hours and 50 minutes, as compared with 
untreated Louisiana and California seeds of the same variety. 


Louisiana seeds. California seeds. 




/ | 
Date sown and number of | Treated. Untreated. Untreated. 
experiment. 
| 
| . < ~ s ~ 
| Number. ea Number. | ace | Number., Serta 
May 3, 1920: | | Per cent. Per cent. Per cent. 
SE SE ee PS Se eee 250 52. 40 250 55. 
|S tS eee Us as 2a EB ae 250 46.00 250 70. 80 
i ae eee Ree ees Pee eee 250 68. 40 250 78. 40 
_. £3 ees ER ES is | epee a 250 64. 80 250 64. 40 
+ 2 RS eee Sees 250 65. 60 250 75.20 
fi ei Was Sati Sees ~ 250 70. 80 | 250 86. 40 
>. SS ee Bi Seg ee bce ae 250, 72.40 | 250 84. 40 
waeeeres St pedi tery th ieti: ayy fore 250 62.00 | 250 78. 80 
May 21, 1921: 
__ Ej Gh a 400 70.50 200 64.00 | 400 72.75 
Ll Se i aes | 400 75.00 200 85.50 | 400 74.00 
es ee eae ene 400 65. 50 200 65. 00 | 400 63.50 
> SS 500 53. 60 500 63.00 f.. > iucs- .5uftot sree 
_ | 2 eee 500 | 70. 60 500 65-660 122. 3.252 TC = eee 
| 0 SS aes Se ae ee Ser arr ee pee ee 1,000 66.10 
eee, fe Tet 500 SD Tid irae le Saree Spee 500 73. 80 
nr ote or ee yn tee ne ce tel ete 1,000 67.00 
_ eee 23 See Tg a ope eee Ly Ree pe 
LPL Di ee ee 4S eee 659Gb. 5s See 2 64280 so. es £ 70.61 
Nishikado and Miyake ® conducted extensive hot-water treatment 
experiments on the Minaribo variety of rice in Japan. Unfortunately, 
the results of this work were not available to the writer until after 
his work on rice was discontinued. These Japanese investigators 
found that the temperature of the hot water which could be used 
effectively on rice depended to a large extent on the length of the 
presoak. They reported no seed injury by treating unsoaked rice 
for 15 minutes at 55° C. The writer found no injury to Honduras 
rice when it was treated at 58° C. for 15 minutes without presoak 
(Table 3). 
The Japanese writers mentioned no injury to seed presoaked for 
different periods up to 16 hours and treated for 5 and 10 minutes in 
water at 54° C., but a 15-minute soak in hot water caused a slight 
decrease in germination. Where they presoaked the seed 24 and 48 
hours, respectively, a 10-minute soak in hot water at 54° C. caused 
some injury. Their results also show that seed treated with hot water 
germinated better than their untreated controls. The writer found 
that a soaking in water at 54° C. for 15 minutes after presoaking for 
16 hours killed the internal fungi and came nearest to giving as good 
germination as the untreated controls. In practically every case, 
however, the germination was slightly lower than that of the untreated 
§ Nishikado, Yoshikazu, and Miyake, Giichi. Momidane no shédoku narabini ine-gomahagareby6 
no yoboho. [Disinfection of seed rice in relation to the prevention of Helminthosporium rice blight.] 
1. Momidane no onto shinsekiho. [Hot-water treatment of seed rice.] Jn By6chd-gai Zasshi (Jour 
Plant Protection), v. 5, no. 9, p. 693-712 (1-20). 1918. 

