382 



Journal of Agricultural Research voi. xviii. No. 7 



EXPERIMENT I 



In experiment i , small lots of infected kernels of the Kubanka durum 

 wheat and Chevalier barley were selected. These were exposed to 

 100° to 110° C. in the gas oven for 15-hour and 30-hour periods. About 

 10 series of culture experiments were made on these treated seeds to 

 compare them with the untreated. In each culture 10 kernels each of 

 barley and wheat were placed on potato agar poured plates and incu- 

 bated at room temperatures. Surface disinfection with mercuric chlorid 

 solution (1:1,000), for 30 minutes was used on the untreated kernels in 

 order to disinfect the surfaces. In practically all cases Gibberella, 

 Fusarium, Helminthosporium, and Alternaria developed rather uni- 

 formly from the unheated kernels of wheat and barley, as well as from 

 the kernels which were heated for 15 hours. From the kernels heated 

 for 30 hours, however, only one wheat kernel yielded the fungus Gibber- 

 ella, and one barley kernel yielded Helminthosporium. In both of these 

 cases the fungus growth was very weak and remained so. 



EXPERIMENT 2 



Following these promising leads various grains were treated in a 

 large electrically heated drying oven at a temperature of about 100° C, 

 in order to test the effect of 15-hour and 30-hour exposures on germina- 

 bility. Following the treatment 100 kernels were counted out from 

 each heated sample and the same number from its untreated control 

 and sown in sand in the greenhouse. Table I gives the germination 

 results for this experiment: 



Table I. ^Effect of dry-heat treatment on germination of seed 



Kind of grain. 



Barley . 

 Do 

 Do 

 Do 



Wheat . 

 Do 

 Do 

 Do 

 Do 

 Do 

 Do 

 Do 



Rye . . . 



Oats. . . 

 Do 

 Do 

 Do 



Variety. 



Hulless 



Beldi 



Manchuria ^crop of 1917) 



Manchuria (crop of 1912) 



Winter wheat 



Turkey 



Kharkov 



Kanred 



Russian 



Marquis 



Dawson Golden Chaff 



Marquis 



Winter rye 



Wisconsin Pedigree No. i 



Wisconsin Pedigree No. 5 



Sixty-day (South Dakota 165) 



Swedish select (South Dakota 112) 



Percentage of germination. 



Not 

 treated. 



94 



73 



100 



96 



93 

 96 



99 



98 



100 



100 



93 

 92 



95 

 98 

 90 



Exposed at about 

 100° C. for — 



15 hours. 30 hours. 



72 

 69 

 96 



79 

 92 

 80 



97 

 100 



99 

 93 

 73 

 94 

 88 



94 

 66 

 81 

 90 



71 



47 

 88 

 6i 



91 

 78 



97 

 94 

 92 

 72 

 82 

 90 

 62 

 67 

 85 



