8 BULLETIN 1116, U. S. DEPARTMENT OF AGEICULTUEE. 



degree of infection, represent the rate at which the seedUngs were 

 killed or injured by these fungi after the seed germinated, Hon- 

 duras and Wataribune seed from California, as shown, germinated 

 much better than Louisiana seed of these varieties and were com- 

 paratively free from fungi, especially of the types which cause injury. 

 Honduras rice was selected for the hot-water treatments, as it is 

 a good commercial rice and one of the most susceptible to attack by 

 these internal fungi. Table 3 shows the results of treatments on 

 January 24 and February 2, 1920. The seed was sown in sterile 

 agar plates, 20 seeds per plate. 



Table 3. — Effect of hot-ivater treatment on the germination of Honduras rice seeds and 

 on fungi carried within the seeds. 



Date and 

 niunber of 

 experiment. 



Pre- 

 soaked 



Soaked in 



Germi- 



Infec- 



Date and 

 number of 

 experiment 



Pre- 

 soaked 



Soaked in 



(ip.rmi- 



Infec- 



in tepid 

 water. 



hot water. 



nation. 



tion. 



in tepid 

 water. 



hot water. 



nation. 



tion. 



Jan. 24, 1920: i 



Hours. 



"C. 



Min. 



P.ct. 



P.ct. 



Jan. 24, 1920: i 



Hours. 



°C. 



Min. 



P.ct. 



P.ct. 



No.l 



16i 



55 



10 



83 



3 



No. 18 



%\ 



57 



15 



96 



52 



No. 2 



16J 



55 



15 



78 



1 



No. 19 



58 



15 



98 



40 



No. 3 



, 16i 



54 



15 



87 



1 



No. 20 



(}) 



(3) 



(3) 



96 



62 



No. 4 



l^ 



56 



10 



59 



13 



No. 21 



16* 



(3) 



(5) 



92 



45 



No.5 



l^ 



56 



15 



47 



3 



No. 22 



4 



(«) 



(^) 



94 



61 



No. 6 



m 



57 



10 



43 



5 



No. 23 



2 



(3) 



(») 



94 



67 



No. 7 



16} 



58 



10 



2 



1 



Feb. 2, 1920: « 













No. 8 



4 



55 



15 



93 



17 



No. 24 



16f 



53 



20 



90 



2 



No.9 



4 



56 



10 



91 



24 



No. 25 



16| 



53 



15 



91 



4 



No. 10 



4 



56 



IS 



86 



19 



No. 26 



161 



53 



10 



86 



13 



No. 11 



4 



57 



10 



66 



5 



No. 27 



16| 



54 



' 20 



76 



3 



No. 12 



4 



57 



15 



75 



4 



No. 28 



16f 



54 



15 



93 



1 



No. 13 



4 



58 



10 



72 



3 



No. 29 



16| 



54 



10 



81 



3 



No. 14 



4 



58 



15 



74 







No. 30 



16| 



55 



15 



71 



3 



No. 15 



2 



56 



15 



89 



20 



No. 31 



16| 



55 



10 



91 



2 



No. 16 



2 



57 



15 



78 



14 



No. 32 



161 



(■') 



(n 



97 



52 



No. 17 



2 



58 



15 



81 



15 



No. 33 



(?) 



(») 



(3) 



96 



47 



1 Soaked at 37° C; germination in 10 days; imection in 13 days. 2 Not presoaked. ^Nottreated. 



■< Soaking started at 35° C, and the water was then allowed to come to room temperature; germination 

 and infection in 8 days. 



Table 3 shows that the long presoaking period is more desirable. 

 In each case the 15-minute treatments at 54° C. gave the best results, 

 in both seed germination and fungus control. 



Further tests were made by soaking seed of Honduras rice from 

 Louisiana at 54° C. for 15 minutes, after presoaking 16 hours and 50 

 minutes in tepid water, and then sowing it along with untreated seed 

 and seed of the same variety which was grown in California. Soil 

 from a field where rice had never been grown was placed in large cans 

 (16 by 16 inches and 15 inches deep), and the 50 and 100 seeds were 

 sown in each can. The soil was in excellent condition, so the seed 

 germinated readily, and none of the seedlings showed signs of blight. 

 Table 4 gives the results of the germination of this seed. 



