Whyte — 29 — Research in Vernalization 



and Clydesdale oats. Drying the vernalized seeds and exposing them to 

 warm temperatures decreased or nullified the vernalization already pro- 

 duced. 



The location of the American sugar beet seed industry in areas vv^here 

 thermal induction, that is, vernalization in the field under the natural en- 

 vironment, is guaranteed, is an interesting example of the practical appli- 

 cation of this type of research. Details are given in Chapter 18 of Crop 

 Production and Environment (Whyte, 1946). 



India: — Agricultural physiologists in India have shown much in- 

 terest in the developmental physiology of the crops grown in that country, 

 and a clear appreciation of the problems at issue in the study of the relations 

 between growth and development. For example, the degree of interest 

 is indicated by the fact that a discussion on vernalization was held by the 

 Imperial Council of Agricultural Research in December, 1939, at which it 

 was emphasized by some of the attending physiologists that (a) experimental 

 data must be obtained to discover whether particular strains of a selected 

 crop will or will not respond to vernalization; (b) to obtain this information 

 experiments with different strains should be undertaken in different re- 

 gions; and (f) a study of the effect of the prevailing after-sowing environ- 

 mental factors of given regions on the life cycle of both vernalized and un- 

 treated seeds is essential in order to evaluate the practical possibilities of 

 the method for Indian agriculture. In discussing the question of practical 

 application. Sen (1940) reviews some technical aspects which will require 

 to be considered before the method can be expected to become part of the 

 routine agronomic practice of India. It is not anticipated that Indian culti- 

 vators will master vernalization on their own, and Sen suggests that a 

 central station for vernalization should be opened, as most seeds can be 

 dried, stored and distributed after vernalization without suffering damage. 



It is a well-known part of the vernalization technique that a certain 

 minimum amount of germination (growth) is essential before vernalization 

 can be effective. When vernalizing mustard, one of the Indian crops on 

 which experiments have been made, this period has to be watched very 

 carefully, as only unsplit vernalized seeds can have any practical value (Sen 

 and Chakravarti, 1942). Sprouted chilled seeds have to be sown very 

 carefully as drying is fatal for them ; unsplit seeds can be dried and stored 

 without losing their subsequent germinating capacity. Having found that 

 vernalized seeds of mustard produce plants which flower significantly earlier 

 (Sen and Chakravarti, 1938), these workers in the United Provinces 

 of India made subsequent experiments for 4 years to discover (o) the op- 

 timal conditions and period of chilling necessary to induce maximum ver- 

 nalization in unsplit chilled seeds, {b) response of different strains, (c) 

 effect on progeny, (c?) period for which unsplit chilled seeds can be dried 

 and stored without reversal of vernalization, and {e) the eflfect of the tem- 

 perature and daylength subsequent to sowing on the developmental physiol- 

 ogy of plants from vernalized and control seeds. 



The technique of vernalization used by Russian and other workers has 

 been fully described elsewhere ( I. A. B. 1933, 1935) ; it may be of interest 

 to describe the technique used under Indian conditions by Sen and Chakra- 



