Vernalization and Photoperiodism — 8 — A Symposium 



than the Soviet Union as vernalization (Imperial Agricultural Bureaux, 

 1933). The technique had as its theoretical basis the principle of phasic 

 development. Although it is not possible to discuss this controversial hypo- 

 thesis here, it is necessary to give the principles postulated by Lysenko in 

 order to appreciate the Russian interpretation of the results obtained in this 

 work. 



In the 4 or 5 years up to and including 1934, Lysenko formulated his 

 theoretical conceptions as follows : 



(a) growth and development are not identical phenomena; 



(&) the entire process of the development of an annual seed plant consists of in- 

 dividual elapes or stages ; 



(c) the stages or phases always occur in a strict sequence, and a subsequent stage 



cannot commence until the preceding stage has been completed; 



(d) diflferent stages of development of the same plant or crop require different en- 



vironmental conditions for their completion. 



These postulates are related to the technique of vernalization in the fol- 

 lowing way. If growth and development are not identical phenomena, it 

 should be possible to reduce the rate of progress of growth to a minimum 

 while allowing for rapid development. Lysenko expressly confines his dis- 

 tinction in terms of the rate of growth and development, the former meaning 

 the rate of accumulation of dry matter or increase in size of a plant, the latter 

 meaning the rate of progress through the stages of development as postulated 

 by him. The technique of vernalization is based on a very reduced rate of 

 growth, in order to prevent formation of seedlings, combined with a rapid 

 rate of development under the influence of the optimal environment, that is, 

 low temperature. 



Discussion of postulates (b) (f) and (d) is outside the scope of this 

 review, but it should be noted that Lysenko assumed that the low tempera- 

 ture used in the vernalization technique is an obligatory requirement for a 

 certain phase of development ; once that requirement has been met, the seed, 

 seedling or plant can proceed to the next phase. This strict sequence of 

 phases is strongly criticized by physiologists in other countries ; a number 

 have expressed the view that low temperature is not obligatory for ultimate 

 reproduction, and that vernalization by short day is possible. If it is sup- 

 posed to be the hght period of a short day which has the vernalizing effect, 

 obviously this could not operate on soaked grain kept in complete darkness. 



According to the Russian literature, vernalization rapidly became a reg- 

 ular agronomic practice throughout Russia. It was used to ensure reliable 

 crops in regions in which the growing period was short owing to frost or 

 drought, or to ensure the production of two crops per season on the same 

 land (for example, a grain crop followed by a catch crop for green manure 

 or forage). Courses for farmers were held at the Institute at Odessa and 

 elsewhere. In most parts of Russia the low winter temperatures made it 

 possible for farmers to vernalize their grains and seeds in the barns, once 

 the elements of the technique had been acquired. 



From data collected by M. A. Oljhovikov, the following acreages in 

 the U.S.S.R. were sown with vernalized seeds in the years 1932-7 inclu- 

 sive: 



1932 43,000 



1933 200,000 



