July IS. 1920 



Presoak Method of Seed Treatment 



373 



all of the presoak-treated seeds as compared with the controls. This 

 is brought out also in Plate 72. 



EFFECT OF 6 HOURS' PRESOAKING FOLLOWED BY FORMAILN I TO 200 TREATMENT 

 ON GERMINATION OP WHEAT SEED 



The beneficial effect of the presoak method is strikingly shown in an 

 experiment where a much stronger solution of formalin was used. Seeds 

 of three varieties were treated for 10 minutes with formalin i to 200 

 and were then kept moist (covered) for 6 hours, dried overnight, and 

 planted in the greenhouse. Another set of seeds received the same 

 treatment but were first soaked in water 10 minutes, drained, and kept 

 moist 6 hours before receiving the formalin treatment. This strength 

 of I to 200 had previously been found to cause a very considerable injury 

 to germination. Table V and figure 2 show the percentage of germina- 

 tion on the sixth day. 



Table V. — Effect 0/ 6 hours' presoaking followed by formalin i : 200 treatment on germi- 

 nation of wheat seed 



Here the 6-hour formalin i to 200 treatment reduced germination 

 32 to 40 per cent below that of the controls, while the reduction was 

 only 9 to 13 per cent where the same treatment was preceded by 6 hours' 

 water presoak (PI. 73.) 



EFFECT OF 6 hours' PRESOAKING FOLLOWED BY FORMALIN I TO 32O TREATMENT ON 

 GERMINATION OF WHEAT SEED 



Formalin i to 320, or one pound of formalin to 40 gallons of water, 

 was next used, since that is the strength now recommended for the 

 cereal smuts. Besides the presoak procedure so far followed, a test was 

 made (experiment XI) of the effect of an actual soaking in water for 5 

 hours, followed by thorough draining for a few minutes, then 10 minutes' 

 soaking in the formalin i to 320, then covering for 7 hours before drying 

 and planting. Experiment XII was conducted to test the effect of an 

 actual soaking in water for 4 hours, followed by thorough draining for 

 a few minutes, then soaking in formalin i to 320 for 10 minutes, drain- 

 ing, covering 6 hours, drying, and planting. The results obtained are 

 shown in Table VI and figure 3. 

 177286°— 20 4 



