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Journal of Agricultural Research voi. xvui. No. 7 



untreated control. They were all sown in a thin layer of sterile sand over 

 sterile garden soil in the greenhouse. Table III summarizes the results 

 obtained. 



Table III. — Effect of dry-heat treatment in experiment 3 on seed germination and the 

 development of Helm^inthosporiun sativum in barley 



Table III shows two things: First, that the barley was not killed by 

 the very severe treatment, in fact proved quite resistant; second, that 

 while there were heavy infections of Helminthosporium sativum in the 

 untreated seed lots, there was perfect control of the disease in those 

 treated. These conditions are illustrated in general in Plates 48 and 49. 



In Plate 48, A, the two groups represent all the 85 plants resulting from 

 the greenhouse experiment on the 100 untreated kernels of Chevalier 

 barley referred to in Table III. At the left are shown the 21 plants with 

 distinct leaf lesions from attacks of Helminthosporium sativum, while in 

 the larger group at the right are represented the remaining 64 plants 

 from the untreated seed that did not show leaf lesions. That all the 

 plants in both groups showed marked darkening of the kernels is evident, 

 also that many showed markedly discolored roots. The dark color of 

 these kernels and the root discolorations are shown more strikingly in 

 Plate 49, A, on the 5 plants at left. 



In Plate 48, B, are shown all the 71 plants resulting from parallel green- 

 house experiments on the 100 treated seeds of Chevalier barley referred 

 to in Table III. These were perfectly free from Helm.inthosporium sativum, 

 attacks. Their bases were usually clear and clean. The kernels were 

 much lighter-colored than untreated ones (PI. 48, A), and the roots also 

 were free from discoloration. This is more clearly seen in Plate 49, A, 

 where typical plants from both groups are represented. The 5 plants at 

 the right are from treated seed, while the 5 at the left are from un- 

 treated seed. 



Although the infections were less severe in the other varieties, the results 

 agree in general with those brought out in detail for the Chevalier barley. 

 That is, infections resulted from untreated seed, and perfectly clean plants 

 resulted from dry-heat-treated seed as shown in Table III. 



