Jan. 3. 19J0 Treatment of Cereal Seeds by Dry Hedt 



383 



The results from this experiment show convincingly that good dry 

 seed of barley, wheat, oats, and rye is able to withstand surprisingly 

 well the high temperature used, up to 30 hours. Previous tests had 

 shown this time and temperature to be fatal to even the persistent 

 parasites. The Beldi barley used in the foregoing experiment was 

 moderately infected with Helminthosporium sativum. Good data on 

 the eflfect of the treatment on this parasite were obtained in the ger- 

 mination boxes as follows: Nine of the 73 plants from the untreated 

 control seed and 9 of the 69 plants from the seed treated for 15 hours 

 developed typical primary lesions of //. sativum and showed marked 

 basal browning, while none of the 47 plants from the seed treated 30 

 hours showed either primary lesions of any kind or any basal browning. 

 All plants from the treated seed were a trifle slow in starting, but in the 

 second-leaf stage they had overtaken or surpassed the others and con- 

 tinued to develop normally until taken out. Table II summarizes the 

 results from this barley infected with H. sativum. 



Table II. — Effect of dry-heat treatment in experiment 2 on germination and the develop' 

 m£nt of Helminthosporium sativum in Beldi barley * 



Treatment. 



Number 



of kernels 



sown. 



Number 



of kernels 



germinated . 



Number 

 of plants 

 with pri- 

 mary leaf 

 lesions. 



Basal 



browning. 



None , 



15 hours at 100° 

 30 hours at 100° 



100 



ICXJ 



100 



73 

 69 

 47 



+ 

 + 



1 Seed sown in sand Mar. 28. Observations made Apr. 9. 



While this was a weak sample of barley, as shown by percentage of ger- 

 mination in untreated seed, the results as to the effect of the treatment on 

 the disease are striking — the 30-hour treatment completely eliminated 

 the disease. 



EXPERIMENT 3 



Two other series of treatments were then undertaken, and the seed 

 treated was used for further germination and infection experiments and in 

 field sowings. In these experiments only seeds that were known to be in- 

 fected with various diseases were used. The third experiment was started 

 April 22 and completed April 23. The gas oven was used, as in experi- 

 ment I, and was watched very carefully through the 30 hours. Observa- 

 tions of the temperature were made at least every half hour and during 

 most of the time at shorter intervals. The temperature range was from 

 95° to 105° C, averaging about 100° throughout. Samples of about i 

 pint each of four different seed lots were used for germination tests and 

 field sowings. For the germination tests, 100 kernels were counted 

 from each treated sample and a like number from each corresponding 

 153425°— 19 4 



