CONSIDERATION OF PLANT GROWTH 187 



ing it at a temperature of about 60° F. for twenty-four hours 

 to start germination. Next the temperature is lowered to 

 about freezing for about two weeks. This prepares the grain 

 to begin normal growth in the spring, after which it can be 

 dried and kept until the soil is in condition for seeding. It 

 would appear that the same growth reactions take place with 

 this treatment that take place in fall-sown wheat. The Rus- 

 sians claim extensive use of this method of growing wheat. 

 They believe vernalization can be applied to many other 

 plants in many other ways. 



To illustrate in another way, plants requiring short days 

 and warm soil may be given just enough moisture to allow 

 some — it is not clear which — physiological activities to go on 

 for a week or longer, but only enough to make little or no 

 growth, while at the warm temperature of the summer and 

 in the dark. This, the Russian investigator, Lysenko, says 

 gives the plant its needed amount of warmth and darkness 

 for development, and it will be able to grow to maturity with 

 lower temperature and longer days than it requires when 

 planted untreated. Time will be necessary to test these 

 methods under many conditions and to simplify the pro- 

 cedure. 



The rapid growth of many plants in the far north with 

 continuous daylight indicates that at least some plants can 

 make food and grow efficiently under what in industry we 

 would call twenty-four-hour shifts. The great question re- 

 mains, can we learn to control the many enzymes, hormones, 

 and growth regulators in an artificial manner to speed up the 

 growth of plants in an environment where they do not natu- 

 rally grow? 



REFERENCES 



Bell, G. D. H., "Experiments on Vernalization," Journal of Agricultural Science, vol. 26, 



pp. 155-171, 1936. 

 Burkholder, P. R., "The Role of Light in the Life of Plants," The Botanical Review, vol. 



2, pp. 1-52, 97-128, 1936. 

 Hill, J. B., L. O. Overholts, and H. W. Popp, Botany, McGraw-Hill Book Co., 1936. 

 Meyer, B. S., and D. B. Anderson, Plant Physiology, D. Van Nostrand Co., 1939. 



