Z CIRCULAR 377, U. S. DEPARTMENT OF AGRICULTURE 



completed in total darkness. Other investigators 2 , however, have 

 shown that this is not necessary or at least not for some seeds. 



In the case of plants requiring high temperatures, such as com, 

 foxtail millet, soybeans, Sudan grass, and sorghum, the vernalizing 

 process, according to Lysenko, is very much the same as with low- 

 temperature plants. In his experiments, where high temperatures 

 were used, sufficient moisture was added to the seed to induce swell- 

 ing or germination, and the swollen or germinated seed was then kept 

 for from 5 to 10 days at a temperature of from 20° to 30° C, depend- 

 ing upon variety. 



The requirements for several different lands of seed as given by 

 Lysenko are shown in table 1 . 



Table 1. — Requirements to induce vernalization j or different kinds of seeds, accord- 

 ing to Lysenko ! 



Crop 



Ratio of 



water to 



weight of 



seed 



Tempera- 

 ture dur- 

 ing ver- 

 nalization 



Time of 

 exposure 



Crop 



Ratio of 



water to 



weight of 



seed 



Tempera- 

 ture dur- 

 ing ver- 

 nalization 



Time of 

 exposure 





Percent 

 30 

 26 

 26 



° C. 

 20-30 

 25-30 

 25-30 



Days 

 10-15 



5 

 8-10 





Percent 

 26 

 75 



C. 



25-30 

 20-25 



Days 

 8-10 



Millet 





10-15 



Sudan grass 







Since the publication of Lysenko 's results, workers in the United 

 States have attempted to duplicate his experiments. Many data 

 have been published regarding the effect of low-temperature treat- 

 ments 3 but few regarding high-temperature treatments, and in the 

 latter case Lysenko's findings have not been substantiated. 4 



MATERIALS AND METHODS 



The factors entering into the vernalization treatment were moisture, 

 temperature, light, and time. Ordinary commercial seed of the 

 various crops was used which in most cases had a high percentage of 

 germinable seed. In the case of crotalaria and hairy vetch, however, 

 hard seeds were present in varying amounts, which increased the 

 percentage of moisture absorbed, as the entire amount of moisture 

 applied was taken up by fewer seeds than would have been the case 

 had no hard seeds been present. 



The amount of water added to the various lots and varieties varied 

 with the amount necessary to induce germination and further in ac- 

 cordance with the object of the experiment. Stoppered bottles were 

 at first used to maintain the moisture content of the seed at a definite 

 percentage, but these later were replaced by Petri dishes. With the 

 lapse of time there usually was a gradual loss of moisture from the 



2 Spraoue, F. S. experiments ox iarovizing corn. Jour. Agr. Research 48: 1113-1120, illus. 1934. 



s Martin, J. H. iarovization in field practice. U. S. Dept. Agr., Bur. Plant Indus., 13 pp. 1934. 

 [Mimeographed.] 



McKinney, H. H., and Sando, W. J. earliness and seasonal growth habit in wheat. Jour. 

 Heredity 24: 169-179, illus. 1933. 



Sando, W. J., Swanson, A. F., Hubbard, V. C. Smith. G. S., Suneson, C A., and 



Sutherland, J. L. field experiments with vernalized wheat. U. S. Dept. Agr. Circ. 325, 8 pp. 1934. 



* Sprague, F. S. See footnote 2. 



Kirk, L. E. division of forage plants, report of the dominion agrostologist. Canada Expt, 

 Farms Rept. 1934, 



