Vernalization and Photoperiodism — 14 — A Symposium 



glutathione were all lower in grains vernalized in ethylene chloride. The 

 oxidation-reduction processes are intensified during vernalization, but there 

 is no relation between content of sugars and mono-amino-acids and vernali- 

 zation. 



Sapoznikova (1935) analysed vernalized seed of Lupinus angustif alius. 

 The content of reducing sugars in seeds treated at 6 to 7° C. increases with 

 the progress of vernalization, a fact regarded as suggesting an increasing 

 activity of the enzymes acting on carbohydrates ; however the content of re- 

 ducing sugars gradually falls in seeds vernalized at 4 to 5° C. The amount 

 of active enzymes rises with vernalization at 6 to 7° C. to a maximum on 

 the last day of treatment ; enzymes increase less rapidly with vernalization 

 at 4 to 5° C. during the first 12 days and then fall. The control of active 

 enzymes is measured by their activity at 35 °C. The protease content in 

 seeds vernaHzed at 6 to 7°C. was found to rise to a climax on the day ot 

 sowing, while in those vernahzed at 4 to 5° C. its changes were indefinite. 

 The activity of catalases, peroxidases and respiration varied in the different 

 series. Marked activity of catalases and peroxidases is a feature of ver- 

 nalized lupine seeds that give rise to plants with a reduced vegetative period, 

 and this character is stated to be useful for distinguishing vernaHzed from 

 unvernalized seeds. 



From determinations of nitrogenous substances (total N, insoluble and 

 soluble N, amino-N, amide-N, and ammoniacal N) in seeds and plants dur- 

 ing vernalization and in those under conditions which prevent vernaliza- 

 tion, KoNOVALOV (1938) found their behaviour to vary considerably. When 

 vernalization was prevented, the disintegration of the proteins extended to 

 the end products, whereas during vernalization the proteins retained their 

 form, but became more readily soluble. This worker concludes that nitro- 

 genous substances appear to be re-synthesized during vernalization, and re- 

 gards this transformation as a distinctive feature of the vernalization pro- 

 cess. Pasevic (1940) found that vernalization induces changes in the pro- 

 tein substances of the wheat germ affecting both their colloidal state and 

 their amino-acid content. 



In some early studies on the effect of vernalization on the rate of ac- 

 cumulation of dry matter, Konovalov (1936) found that vernalized plants 

 of wheat and lentils accumulated more dry matter per unit of time than the 

 unvernalized control, and the yield of organic matter was consequently in- 

 creased. More recently, Konovalov and Popova (1941) found that the 

 synthesizing capacity of vernalized plants is higher than in the unvernalized 

 controls. By the time of earing, vernalized plants contained 26 per cent 

 more organic matter than those from soaked and germinated seeds and 52 

 per cent more than plants from seeds sown dry. 



Konovalov (1944) has continued his work at the Timirjazev Institute 

 of Plant Physiology, Moscow, on the effects which vernalization of seed 

 exerts on the growth and physiological processes in the leaf relative to the 

 yield of grain or seed ultimately produced. The chief concern in these ex- 

 periments has been productiveness of a plant as governed by the intensity 

 of photosynthesis, the extent of its leaf area, and the duration of activity 

 by the leaves. 



The intensity of photosynthesis was not materially affected by vernaliza- 



