THE THEORETICAL PRINCIPLES OF VERNALIZATION
T. D. Lysenko

INTRODUCTION

THE THEORY of phasic development is a general biological theory. For that very reason it holds for all branches of agrobiological science and is widely applied in socialist agriculture. A far from complete list of deductions from the theory of phasic development which are already being applied in socialist agriculture includes the following: a) reduction of the vegetative period of cereal plants under field conditions as a method of combating hot dry wind; b) vernalization of potatoes and the planting of eyes of vernalized tubers as a means of economizing planting material, and at the same time obtaining larger yields; c) the discovery of different degrees of winter hardiness at different stages of development and, following from this, measures for preventing winter crops from perishing in the winter; d) the method of producing varieties of winter crops by selection from populations by means of planting undervernalized seed; e) discovery of the causes of the degeneration of potatoes in the South and the planting of this crop in the summer as a means of preventing the degeneration of seed potatoes in the dry steppe regions; f) the theoretical principles of the deliberate choice of parental pairs for crossing in breeding varieties of different crops; g) discovery and formulation of the laws of segregation in conformity with the length of the vegetative periods as the theoretical basis of new methods of culling in the breeding process and an entirely new presentation of the problems of seed growing.

1At a meeting at the Seed-Growing Farms Union, January 16, 1934.

The breeding in two and a half years, on the basis of the theory of development by phases, of a previously planned variety of spring wheat for districts of the Odessa Region is, in our opinion, one of the most striking victories of the theory of phasic development. Not so long ago, the soundness of the principles on which this work was conducted was challenged by many scientists.1 The theory of phasic development, as a general biological theory, and the deductions that followed from it were put to the severest test, the test of practice, and everywhere emerged victorious. [10] All this was achieved at an ever-increasing tempo of work which, in the shape of new methods of growing plants, propagating seeds, etc., is an inseparable aspect of work based on the theory of phasic development.

The progress which the general theory of biology has made in the mainstream of our practical life once again shatters the bourgeois falsehood that there are two truths—theoretical and practical.

1Marx-Engels, Gesamtausgabe, Erste Abteilung. Band 3. Berlin 1932, S. 121, 122.

". . . the solution of theoretical contradictions is possible only by practical means, only as a result of the practical energy of man, and is, therefore, under no circumstances the task of cognition alone, but an actual task of life .... The assumption that there is one basis for life and another for science is a priori false," wrote Marx.1 The theory of phasic development conquers in practice and by practice. This theory holds that everything in a plant, every one of its properties, characters, etc., is the result of the development of the hereditary foundation under concrete environmental conditions. The hereditary foundation, in its turn, is the result of the whole of preceding phylogenetic history. This biological history, which proceeded by the selection of adaptations to definite conditions of existence, resulted in the demands which the plant organism, throughout the whole period of its individual history, beginning from the zygote, makes upon the definite conditions of its development. These demands are the reverse sidle of the adaptations worked out in the historical process.

The phylogenetic history of the organic world did not, however, proceed in a straight line. For that reason, the biology of the individual plant organism is by no means uniform in its adaptations, and hence, in its demands. It has turning points, phases of definite duration. These phases constitute the most general biological stages in the individual development of the plant. Concentrated at the growing points of the plant's stem, the phasic processes, being specifically the development of the hereditary foundation, are the innermost processes in the life of plants. To discover the biophysics and biochemistry of the phasic processes means discovering the biophysics and biochemistry of the most intimate processes of the life of the plant cell. This most difficult problem will, in time, be solved, but the course of investigaton that leads to this solution is an intricate one. What a vulgarly simplified conception of this problem is held by those investigators who, finding, or, more often, making attempts to find, changes in the chemical reactions of plants at one or other stage of development, think that they have discovered the innermost "nature" of vernalization, of the photo phase, etc.! The chemical indicators of phases are only a few of the many indicators, and although they are undoubtedly extremely important, they are still a long way from the "ultimate substance of life."

The offhand way in which some "discoverers" of the biochemical nature of the phasic processes approach this problem is due to the fact that they [11] regard "vernalization" as "stimulation," as a method which "thrusts" into the normal process of development something that is alien, supplementary, that can easily be chemically isolated and extracted.

Actually, however, vernalization, and the other phases of development, are necessary, normal processes of development of the same type and nalure both under artificially created conditions (the presowing vernalization of seeds which have begun to germinate) and under field conditions. After all, it is possible to induce in any variety of winter crop a process of development of the whole cycle (from seed to seed), a process of plant development, similar to that of a spring plant, both by vernalizing the sowing material and by choosing the suitable field conditions (choice of district and time of sowing).

1The work of M. A. Bassarskaya, a specialist at the Odessa Institute of Selection and Genetics.

We are in favour of studying the chemical, physical, morphological and all other indicators of phasic development. In this respect, the Institute of Selection and Genetics already has some achievements to its credit (different chemical reactions to staining in sectional preparations of vernalized and unvernalized cuttings at the growing points;1 differentiation in the growing points as a morphological indicator of vernalization, etc.). But we are opposed to the view that these indicators constitute the sum and substance of phasic development.

Above all, we are in favour of studying the biology of development, of studying what in development constitutes the specific character of biological relationships. Just as it would be absurd to say that since the physico-chemistry of the hermit crab and actinia is still obscure, therefore the essential nature of their interrelationships is still obscure, so it would be absurd not to regard the study of the biology of the phasic processes as being the study of their essential nature. We do not agree with the theoreticians of the "mechanics of development" who have deserted Darwinism, who operate on the principle: "I shall exert an influence with some agent and see what comes of it," who disregard the role of adaptedness in development (the mechanists), or those who play on this adaptedness and convert it into some sort of immaterial principle (the vitalists). We stand by the principles of Darwinism and study the biological stages of development, which are characterized primarily by turning points in the adaptive requirements of definite conditions of existence.

2 К. А. Тимирязев, Исморический мемод в биолозии, 1921 г., стр. 36-37.
3K. A. Timiryazev, editorial comment on p. 57 of G. Klebs's Willkurliche Entwicklungsanderungen bei Pflanzen. Translation, preface and comments by K. A. Timiryazev, 1905.

We well remember K. A. Timiryazev's statement that "we must have a historical conception of present-day organisms,"2 because "an organ, i.e., the adaptive form, is the result of a historical factor—selection."3 [12]

Following I. V. Michurin, we are developing this Darwinist idea further, not confining ourselves to the morphological formulation of the connection between phylogenesis and ontogenesis, but establishing their biological connection. The course of the phylogenetic process, the creation of organic forms by the selection of adaptations, cannot but affect primarily the very biology of the individual development of the hereditary foundation by determining the latter's demands upon the environmental conditions of its development. The concrete phasic development of the hereditary foundation and the development of organs and characters on the basis of the phases involved proceed only through a given pattern arranging the satisfaction of these demands throughout the entire course of individual development. Various factors not necessarily required for development are also operative here.

The biology of individual development must be studied as the individualization and concretization of the development of the historically formed hereditary foundation, which is the varietal, specific, etc., basis of the development of a plant individual. That is why we are opposed both to the preformism that exists in contemporary genetics and looks for the direct predetermination of characters in the hereditary foundation, skipping the biological stages of development, as well as to the mechanistic epigenesis characteristic of the "mechanics of development," which fails to see that the hereditary foundation is the generic basis of the individual. The hereditary foundation determines the general background, the general character of the plant's cycle of individual development.

The organism has no concretely given characters, nor does it undergo arbitrary changes of form. Winter habit, spring habit, winter hardiness, considerable or inconsiderable tillering, awnedness, colour, etc., are not given in the hereditary foundation, but are the result of the development of the hereditary foundation under the different environmental conditions that take part in the very formation of the organism's concrete characters. At the same time, however, external conditions are not free to turn development in any direction, are not free to turn it back, are not free to cancel the demands made by the given hereditary foundation upon the given conditions of development at any stage. The individual development of a plant organism proceeds on the basis of the biological requirements of a given stage of development of the hereditary foundation itself.

It is precisely because phases of development constitute general biological stages in the individual development of the hereditary foundation itself that these phases constitute the basis of development of each of the plant's characters. Spring habit, winter habit, frost resistance, drought hardiness, pest resistance, length of vegetative period, tillering, etc., cannot be studied apart from the general phases of development, because the formation of all these characters will vary if the course of this or that phase varies (owing to differences in external conditions) and they will differ in the different phases. [13]

Of course, phases constitute only the general basis for the development of characters; for the latter develop under their own external environmental conditions and are subject to their own influencing factors,

The biology of development is the theoretical basis of all branches of agronomic science. The scourge of these departments, to this day, is their peculiar abiologization and divorcement from each other.

The biology of development must connect the disconnected and provide the general background for the study of all the various laws that govern plant organisms. This imposes upon all branches of agrobiological science, upon plant breeding, genetics, physiology, agrotechnique, etc., the task of critically examining their scientific stock-in-trade from the point of view of the theory of development.

Our socialist agriculture needs concrete knowledge. Planned economy demands, and gives rise to, the planning of the development of science. But the planned development of agrobiology can be ensured solely by employing the one and only scientific methodology, that of dialectical materialism, which is the theory that treats of the general laws of development.

The theoretical value of work on vernalization lies in the fact that this method marks the beginning of the conscious control of the development of field crops. However, until recently agricultural science lacked methods of controlling the rapidity of development of field crops. The various species and varieties of field crops whose development did not fit in with the climatic and geographical conditions of a given district were simply cast aside.

The starting point, the theoretical premise of our work on the vernalization of agricultural plants, is the law of the phasic development of plants that we have discovered. The principles of this law of phasic development of plants and some examples of its practical application are expounded in this book.

THE HISTORY OF THE PROBLEM OF VERNALIZATION

In practical farming varieties of annual crops which, although sown in the spring at the same time as other varieties of the same crop, proceed to fruit and ripen earlier than the latter, are called early ripeners. Varieties with a comparatively lengthy period from sowing to ripening are called late ripeners. Lastly, there are crops which, planted in the spring, do not proceed to fruit (to form reproductive organs) even in the autumn. These plants are called winter crops.

Many investigators, here and abroad, sought for that which distinguishes the winter group from the spring group in order to ascertain why winter crops fail to fruit when sown in the spring. Different investigators explained this problem in different ways. Some arrived at the conclusion that winter crops fail to fruit when sown in the spring because these plants need a definite dormancy period, i.e., a halt in their development for a definite [14] time. When sown in the autumn, these winter plants obtain this dormancy period in the winter; if planted in the spring, however, winter plants continue to grow and therefore, in the opinion of these investigators, cannot bear fruit.

The fallacy of this assertion can be proved fairly easily. For this purpose it is sufficient to sow the seeds of several varieties of winter wheat under conditions where for a period of one and a half to two months the temperature ranges from 5°-l0° C.; the plants will then grow all the time and, skipping the dormancy period, will proceed to ear, and later, under a higher temperature, begin to ripen (Fig. 1).

Other investigators, judging by the method of cultivating winter crops in districts with a frosty winter, assumed that in order to be able to fruit, winter plants must be chilled. This assumption also proved to be wrong. It can be disproved by experiments in growing winter plants under conditions where they will not be chilled and yet, in many cases, will fruit. This is confirmed by practical experience in districts where there is no, or scarcely any, frost in winter, and yet winter crops, sown on hundreds of thousands of hectares, ear and fruit after wintering.

A number of other investigators have advanced other explanations for the failure of winter crops to ear if sown in the spring. Lastly, a German professor named Gassner arrived at the conclusion from experiments he had conducted (the results of which he published in 1918) that winter varieties need a cold spell during their first stage of development. This gave rise to the method called the "cold germination" of winter crops. In the cold-germination method, the seeds of winter plants (wheat, rye) must be made to germinate at a temperature slightly above 0° C. The germination is allowed to go on until the rootlets reach a length of 2.5-3 cm. The plants brought to germination in this way can, in some cases, after planting, begin to ear. In the U.S.S.R., this method was tested in the physiological laboratory of the All-Union Institute of Plant Industry in Leningrad by Professor Maximov and Poyarkova. Professor Maximov and Poyarkova conducted their experiments during the winter, in a greenhouse. These experiments showed that with late greenhouse planting (in May, i.e., when in the Leningrad district, where these researches were conducted, the sowing of spring grain crops begins in the fields) winter crops do not ear uniformly and fully, irrespective of whether they germinated in cold or warmth. Only greenhouse planting in the early spring, when the snow still lies in the fields, gave advantage in earing to plants raised from seed that had germinated in the cold.

The facts obtained led these investigators to the conclusion that the cold germination of winter crops does not always produce a corresponding effect, and results in earing only when the sowing is done at definite times.

Thus, these experiments would appear to refute Professor Gassner's argument that winter crops need a cold spell. [15]

Fig. 1. Left to right—winter wheats: Lutescens 0329 (pot No. 191); Stepnyachka (pot No. 183); rye: Petkusskaya (pot No. 167); Tulunskaya (pot No. 175); Yeliseyevskaya (pot No. 125); and Vyatka (pot No. 157)
Sown with ordinary seeds on December 14, 1929, in a greenhouse at a temperature of 5°-10° C. At the end of February the rye plants eared. In the middle of April, after the temperature in the greenhouse had been raised, the wheat too eared

After our investigations, it may be said definitely that the facts obtained by the experiments conducted by Maximov and Poyarkova speak against the "cold-germination" method only. They do not contradict Gassner's argument that in the first stage of their development winter plants need low temperatures. In principle, Gassner's assertion that at a definite stage of development winter plants require low temperatures need not be challenged. The cold-germination method, as such, however, is wrong. By this method it is not always possible under greenhouse conditions to induce winter varieties to ear normally when sown in the spring; and it is almost altogether impossible when the spring sowing is done in a warm period under open field conditions. [16]

In addition to the above explanations of the difference between winter and spring crops, and of why winter crops fail to ear if sown in the spring, a number of other investigators could be quoted. But none of them, whether foreign or Russian, provides a definite solution of the problem as to why winter crops fail to ear when sown in the spring. Not one of these investigators has been able to propose a method that will induce any winter variety to ear when sown in the spring. They have failed to work out any such method not only for the spring sowing of winter varieties under ordinary farming conditions but even for sowing in the open on a square metre plot at research institutions.

The chief defect in the work of the majority of the investigators of this problem was that they failed to set themselves the proper target. The main task they set themselves was not to induce winter varieties to ear when sown in the spring, but to "explain" why they failed to do so; and in their explanations, these investigators proceeded from the erroneous premise that in every district crops like wheat and rye are divided into separate and distinct groups—winter and spring varieties. Actually, however, the varieties of these crops, formed in the process of development of the genus and species, are often in this regard not separate and distinct groups, but an uninterrupted series of transitional forms from greater winter habit to lesser winter habit, i.e., to spring habit. Moreover, these investigators regarded winter habit and spring habit as properties belonging to, or what is the same thing, inherent in, the hereditary foundation of the seed germ, and not as properties acquired in the process of the plant's ontogenetic development.

These investigators lost sight of the fact that in the process of development, the germ or the hereditary foundation (the genotype) may give rise to the property of spring habit under some conditions, and to the property of winter habit under other conditions.

1The Russian term is yarovizatsia.—Tr.

The term vernalization1 appeared in the middle of 1929, when for the first time in the history of agricultural science the winter wheat Ukrainka, following suitable treatment of the sowing material, eared fully and uniformly after being sown in the spring under practical farming conditions. (D. N. Lysenko in the Poltava Region.) The yield of this spring-sown Ukrainka was 24 c. per ha. The fact that a spring-sown winter variety not only eared but produced a good yield seemed extraordinary at first. It seemed to contradict the nature of winter plants. The spring-sown plants, which by their nature have always been winter varieties in our districts, but which behaved like spring varieties (eared), came to be called vernalized plants by the Soviet public. The method of treating the seeds of winter varieties for spring sowing was called vernalization. Similarly, the work we did in studying the causes of the length of the vegetative period of agricultural plants, on the basis of which the vernalization method was elaborated, was referred to as the vernalization of agricultural plants. [17]

Many investigators believe that our work of studying the causes of the length of the vegetative period of agricultural plants consists solely in preparing the seeds of winter crops for spring sowing. This conception of our theoretical and practical work is incomplete and inexact not only today, when research work on the basis of the theory of phasic development is being conducted on a fairly extensive scale; it did not reflect the state of our scientific researches even in 1929.

Although the term "vernalization" appeared only in 1929, I had commenced to study the causes of the length of the vegetative period of agricultural plants at the Kirovabad (Ganja) Plant-Breeding Station (Azerbaijan) as early as 1926. This work marked the beginning of our researches into the vernalization of winter and spring varieties of different crops.

At the end of 1925, at the newly organized plant-breeding experimental station in Kirovabad, I was entrusted with work on breeding legumes for sideration and fodder. The cultivation of agricultural crops in the lowlands of the Azerbaijan S.S.R. calls for irrigation. In the summer dependence on irrigation water was one of the factors that restricted the introduction of southern leguminous plants (mung bean, vigna, and others), as crops for green manure. These plants need high temperature for their vegetation, and, therefore, they can be cultivated only in the summer. But in the summer, cotton—the staple crop in these parts—needs watering and absorbs the available water supply.

From September to the beginning of April the demand for irrigation water diminishes considerably. We decided to make an attempt to select from the family of leguminous plants such genera and species as could develop and provide the green mass necessary for fodder in the autumn-winter and early spring period, i.e., when irrigation water is available. This seemed all the more possible because many districts of Azerbaijan have a long autumn and a comparatively warm winter. Morning frosts do, indeed, go down to 6°-12° C. below zero, but there are only ten days in the year when the average temperature is below zero.

In the autumn of 1925, a collection of legume varieties was sown. For sowing we chose legumes that require relatively low temperatures for vegetation and can withstand morning frost. In the main, we took such crops as peas, vetch, horse beans and lentils. We placed most hope in the early, and not the late and medium, ripeners. The result was not bad. The peas and vetch, in general, came up well. Our assumptions were confirmed. All that was necessary now was to select and improve the varieties needed for this purpose; but in these sowings our attention was drawn to a phenomenon that seemed to us unusual at the time. Some of the varieties of peas, which in ordinary spring sowing—in Belaya Tserkov (Ukrainian S.S.R.), for example—were earliest ripening, behaved like latest ripeners when cultivated in the autumn and winter in Kirovabad. The Victoria variety (a medium ripener under normal conditions of cultivation) turned out here to be the earliest ripener. This variety flowered early and produced a green mass suitable [18] for mowing, or for ploughing in. The above-described facts induced us to investigate the length of the vegetative period of agricultural plants. A solution of this problem was needed for our work of selecting and creating a variety of pea suitable for cultivation in the autumn and winter season.

As the result of a study of the length of the vegetative period of agricultural plants, it was proved experimentally that this period depends on the variety as well as on the external environmental conditions under which that variety is grown. It was confirmed over and over again that some varieties were early ripeners under certain conditions of cultivation and late ripeners under other conditions; conversely, some late varieties became early ripeners when their conditions of cultivation were changed.

It became clear to us that different varieties of the same crop may demand different external conditions for their growth and development. The less the environmental conditions suit the nature of the development of the plants of a given variety, the longer will it take those plants to develop, the longer will be the period from the sowing of the seeds to the ripening of the new seeds. If the external conditions are totally unsuitable for the nature of the development of the plants of the given variety, the plants will be unable to complete their development. They will neither flower nor bear fruit. In practical farming plants of crops which, when sown in the spring, germinate and develop leaves, but do not form reproductive organs even in the autumn (such as wheat, rye, barley, vetch, rape, etc.), are called winter plants.

Thus, we arrived at the conclusion that the question of the spring or winter habit of plants is part of the general question of the length of their period of vegetation.

After this, the question of winter or spring habit inevitably had to be included in our investigation into the causes of the length of the vegetative period of agricultural plants.

In the course of our experimental work we were able to prove that the plants of any variety of wheat, depending upon the conditions of cultivation, may behave like early spring, late spring, and even winter plants, i.e., such as always form only leaves, do not develop stems and do not ear.

In our experiments we observed that plants of the same variety, when grown under different conditions, may, depending upon these conditions, be winter, early-spring or late-spring plants, and that the behaviour of plants of different varieties, when grown under the same definite conditions, may be different. Some varieties of wheat may behave like winter wheat, others like late-spring varieties, and others again like early-spring varieties. From all the material we obtained in our experiments in 1927, we arrived at the conclusion that the length of the vegetative period of plants from the sowing of the seeds to the ripening of the new seeds depends upon the interaction between the plant organism and environmental conditions. By changing external conditions it is possible to change the behaviour of different plants of the same variety. Late-ripening forms may become early ripeners, winter forms may become spring forms, and spring forms winter forms. [19]

Even before 1929, we observed in our experiments that definite groups of varieties can be of winter or spring habit only if sown under definite environmental conditions. For example, field experiments were conducted to ascertain the best sowing dates for different varieties of cereals (rye, wheat, barley). They were sown at intervals of ten days, from August 24, 1926, to August 27, 1927, and from October 1, 1927, to June 1, 1928. The results showed that there is no definite sowing time limit after which all the varieties that behave like winter varieties in other districts begin to behave in Kirovabad, Azerbaijan, like winter varieties, i.e., cease to develop stalks, and spring varieties, on the contrary, continue to develop stalks. Different varieties begin to display winter properties at different periods, and in 2 years (1927 and 1928) they did so on different calendar dates.

March 1928 was colder than the same month in 1927 and for that reason many varieties eared in 1928 even when sown on later dates than in 1927. Table 1 shows the last calendar dates for sowing different varieties: when sown after these dates the varieties failed to develop stalks.

Table 1

  Date of sowing   Date of sowing
Variety 1927 1928 Variety 1927 1928
Rye 3 12/2 3/3 Tr. speciosissimum 1348/5 - 27/3
Kooperatorka 963 22/2 3-10/3   " coerulescens 60/2 - 27/3
Tr. erythrosp. 1325/6 - 3/3   " apulicum 35/1 - 27/3
H. pallidum 133/2 - 10/3   " apulicum 44/1 - 4/4
H. nigrum 174/2 - 10/3   " leucurum 1273 1/4 4/4
H. pallidum 419 12/3 10/3   " leucurum 160/5 - 11/4
Tr. barbarossa 70/1 - 10/3   " apulicum 2634 1/4 11/4
  " nigrobarbatum 1345/1 - 19/3 Av. grisea - 11/4
  " niloticum 1229/1 - 9/3   " brunnea 569 - 23/4
  " ferrugineum 1338/1 - 19/3   " byzantina 952 - 23/4
  " erythrospermum 2627 3/3 19/3        

As is evident from the table, the given collection of varieties, sown on different calendar dates, divides into the winter group and spring group in different ways. Each variety behaves in its own particular way. In some varieties the property of winter habit reveals itself when they are sown on earlier dates; in others, when sown on later dates.

From the large assortment of cereals which, in our experiments, were sown on different dates from winter to summer a striking series of consecutive transitions from spring forms to winter forms could be drawn. In this series it is impossible to distinguish where the winter forms end and where the spring ones begin without reference to the definite dates of sowing, because, depending on the date of sowing, the same forms may be of either spring or winter habit. [20]

From this it follows that the varieties of wheat, and also of rye and barley, that exist in nature are not divided into separate and distinct groups—one winter and the other spring. They are connected by transitional series, from greater winter to lesser winter habit, that is, to spring habit. The winter forms, represented by a correspondingly chosen series of varieties, gradually pass into the spring forms and, vice versa, spring into winter forms. Definite groups of varieties may be winter or spring, if they are sown under definite conditions. It cannot be said that this or that variety is a winter or a spring form unless its inherent properties are linked with the concrete climatic conditions of the district (it would be more correct to say—the conditions of the postsowing period) in which the plants of this variety are to be grown. Now that we have brought into our researches in vernalization as many as 7,000 varieties, collected by the All-Union Institute of Plant Industry from nearly all countries in the world, it is easy to point to thousands of varieties which, when sown in the spring in some districts of the Soviet Union, will behave like spring varieties (i.e., will ear). The same varieties, sown in the same year in other districts, behave like winter varieties (will not ear). Thus, out of the 1,427 specimens of Azerbaijan wheat we sowed in Kazakhstan in the spring of 1932, 79.9% eared (without presowing vernalization). That is to say, under the conditions prevailing in that district, 79.9% of all the Azerbaijan wheats sown behaved like spring forms, and only 20.1% like winter forms. In the same year, 1932, at the Gigant State Farm in the North Caucasus, the same collection of wheats presented a different picture: only 4.8% (as against 79.9%) proved to be of spring habit; the rest, 95.2% (as against 20.1%), turned out to be of winter habit.

The same applies to the question of early- or late-ripening varieties. The behaviour of a definite group of varieties may be such in some districts that for practical farming purposes they will be early varieties, i.e., will ripen earlier than others. In other districts, the same varieties may be late-spring-ripeness. For example, in Table 2 we give a number of wheat varieties that originated in Finland and India. Their behaviour in respect to maturity varies rather sharply with the district in which they are sown. As a rule, in Kirovabad the Indian wheats ear 11 to 19 days earlier than the Finnish; in Odessa, the difference is only 2 to 11 days. When sown in Khibiny, most of the Finnish wheats ear simultaneously with, or even 5 days earlier than the Indian wheats.

Proceeding from this premise, it is easy to arrive at the conclusion that it is wrong to divide all varieties of wheat (or any other plant) into a winter group and a spring group, into an early- and a late-ripening group, without taking into consideration the concrete conditions prevailing in the district where these varieties are to be grown.

As has been already stated, all properties, qualities and characters, including, of course, winter habit, spring habit, early ripening, late ripening, and others, are the concrete result of the interaction between the plant organism and environmental conditions. The fact that it is wrong to divide varieties [21] into winter and spring, early- and late-ripening varieties without linking this division with the concrete conditions of the district (i.e., the conditions of cultivation), does not in the least mean that all varieties are, by their nature, equally early or late ripeners, or equally winter and spring varieties. Different varieties (of wheat, for example) differ in their natures. The conditions of cultivation in different districts also differ. However, winter habit and spring habit, early and late ripening, are the result of the interaction between the natures of plants and external environmental conditions. Therefore, for definite conditions of cultivation (for definite districts) all varieties not only can but must be divided into winter and spring, early- and late-ripening, and other forms.

To ascertain whether a variety in this or that district will be a winter or spring form, the nature of the variety must be experimentally studied. This we have already done in respect to the majority of varieties of cereals.

The object of studying the causes that determine the length of the vegetative period of agricultural plants, which naturally included the problem of winter and spring habit, as well as the early and late ripening of varieties, was to find a method of treating the sowing material in order to change the behaviour of the plants—to convert late-ripening into early-ripening forms, varieties with winter behaviour into spring forms.

In 1928, at the Kirovabad Plant-Breeding Station, we conducted a number of experiments in this direction, under laboratory as well as under field conditions, with different varieties of wheat, rye and barley. We established that the causes oil the late earing of many varieties of these crops and the failure of a number of other varieties to ear under field conditions when sown in the spring are in many cases phenomena of the same order. The cause of this phenomenon with spring sowing under field conditions was found to be the excessive temperature of the postsowing period, which prevented the plant from passing through a definite stage of development. Different varieties may pass through this stage of development (this phase of development) in different lengths of time and under different temperatures. Moreover, it was found that plants may pass through this phase of development even when still in the seed state, i.e., when the embryo has just begun to grow and has not yet broken through the seed integument. All that such sowing material needs is that definite external conditions (suitable temperature, moisture, access to air) be created for it for a definite period of time, depending on the variety. After being sown in the spring under field conditions, the plants of late-ripening varieties obtained from such sowing material may become early ripening, and plants of winter forms may become spring forms. One of the most important facts revealed by these experiments was that varieties of different natures (heredities) require different lengths of time and different conditions (moisture and temperature) of presowing treatment, i.e., the plants of different varieties were found to possess different degrees of winter habit. Under definite conditions it is sufficient to subject the seeds of some varieties to presowing treatment for [22] a period of only 5 days. The seeds of other varieties require 10, 15, 20, 25, up to 60 days of suitable treatment (depending upon the variety) to make these plants behave like spring instead of winter forms in contrast to the simultaneously sown untreated seeds of the same forms. Thus, in our experiments, the problem of winter habit and spring habit, like that of early and late ripening, emerged from the problem of the length of the vegetative period.

Table 2

Place of origin Variety

No. in catalogue
of All-Union
Institute of
Plant Industry

Date of earing; number of days
Finnish wheats were later (+) or
earlier (-) in earing than Indian
wheats at points of sowing
Ganja Odessa Khibiny
Finland ferrugineum 5512 21/5 24/6 18/7
India turcicum 24406 7/5 19/6 21/7
      +14 +5 -3
Finland ferrugineum 13313 23/5 25/6 20/7
India erythroleucon 26586 4/5 20/6 1917
      +19 +5 +1
Finland erythrospermum 5694 18/5 21/6 16/7
India erythroleucon 26598 4/5 18/6 21/7
      +14 +3 -5
Finland erythrospermum 5382 16/5 27/6 19/7
India graecum 25715 4/5 16/6 16/7
      +12 +11 +3
Finland luescens 5696 21/5 21/6 16/7
India graecum 25715 4/5 16/6 16/7
      +17 +5 0
Finland milturum 25702 23/5 25/6 21/7
India alborubrum 23731 4/5 17/6 18/7
      +19 +8 +3
Finland erythrospermum 5694 18/5 21/6 16/7
India turcicum 24406 7/5 19/6 21/7
      +11 +2 -5
Finland lutescens 5693 21/5 23/6 18/7
India erythroleucon 26598 4/5 18/6 21/7
      +17 +5 -3
Finland lutescens 5696 21/5 21/6 16/7
India nglicum 23842 4/5 17/6 19/7
      +17 +4 -3
Finland erythrospermum 5702 21/5 24/6 19/7
India erythroleucon 26586 4/5 20/6 19/7
      +17 +4 0

 [Fig2]

Fig. 2, Leucurum 160/5
Sown in Ganja on April 15, 1929; number of days of presowing vernalization for normal earing 20; with fewer days, of vernalization either does not ear at all, or ears late

[Fig3]

Fig. 3. Nigrobarbatum 1348/10
Sown in Ganja on April 15; presowing vernalization lasts 36 days, alter which the wheat ears normally

[23]

The result of these researches was reported to the All-Union Genetics Congress in Leningrad (January 1929).

The report on our investigation into the causes of the failure of winter varieties to ear when sown in the spring and on the connection between this problem and the length of the vegetative period introduced nothing definite or new in the conceptions of the participants in that congress. As was stated above, quite a number of reasons had been advanced hitherto for the failure of winter varieties to ear when sown in the spring, and at best, the upshot of our report was that still another explanation was put forward. It was difficult for the audience to determine which of these explanations was correct. One of the principal objections raised against our propositions was that if applied in other districts the results might turn out to be different from those we obtained at the plant-breeding station in Azerbaijan, just as was the case with the "cold-germination" method, which in Professor Maximov's experiments proved effective (relative to earing) only when the seeds were sown at definite dates.

1This sowing was not accidental. On my suggestion it was done by my father, D. N. Lysenko, on his farm.

In the spring and summer of 1929 we continued our research work on this problem at the plant-breeding station in Azerbaijan on a fairly extensive scale, without divorcing it from the general problem of the length of the vegetative period of agricultural plants. In the same summer (1929) the Soviet public learned from the press of the full and uniform earing of winter wheat sown in the spring under practical farming conditions in the Ukraine.1

This practical sowing confirmed the chief conclusions of our researches, after which they received general recognition. The Soviet public came out in support of our explanation of the length of the vegetative period of plants. By order of the People's Commissariat of Agriculture, a special laboratory, and later a department, was established at the Ukrainian Institute of Selection and Genetics (Odessa) to study this problem. To test and further elaborate our idea of controlling the length of the vegetative period of agricultural plants, hundreds of collective-farm experimenters and state-farm workers were drawn into the work in 1930, besides the opening of the laboratory. Had this not been done, not only would our laboratory researches have gotten no further than the four walls of the laboratory, not only would they not have been applied to the fields, but the working out of the theory that treats of the problem would not have been as successful as it is today.

In 1935, the experimental and practical sowing of vernalized spring cereals alone was carried out by over 40,000 collective and state farms on a total area of 2,100,000 ha. Practice has shown that collective- and state-farm experiments on the problem of vernalization, when properly linked up with the work of research institutions, yield results, both theoretical and practical, that cannot be expected when the work is conducted by the research institutions alone. [24]

Table 3

SPRING SOWING OF VERNALIZED 1930 WINTER WHEAT (ODESSA)

No. Variety Number of days necessary for vernalization, temperature ranging from 0° to +1° C.1
1 Winter wheat 808 (1/26), Verkhnyachka station 16
2 Novokrymka 0204 36
3 Kooperatorka 36
4 Erythrospermum 917, Kharkov station 36
5 Ukrainka 41
6 Stepnyachka 0464 41
7 Hostianum 237 46
8 Lutescens 329, Saratov station 46
9 1060/10, 46
10 Dürabl, Ivanovskaya station 46
11 Winter wheat 037, Belaya Tserkov station 46
12 Minchardi 46
13 No. 15, Ukr. Inst. of Selection and Genetics 52
14 No. 14, 52
15 White awned 040 52
16 Winter wheat 564/115 (1/26) Verkhnyachka station 53
17 No. 2, Ukr. Inst. of Selection and Genetics 57
18 Winter wheat Erythrospermum 132/5, Ganja station 57
1In Odessa the spring of 1930 was cool and prolonged. In years of hotter and shorter springs, the seed of each variety must be vernalized before sowing for 5 days longer than shown in the table.

The collective- and state-farm experiments of 1930 clearly demonstrated that all the winter plants of wheat, rye, rape, vetch, and others, can be induced not only to bear under practical farming conditions when sown in the spring, but also, in many cases, to produce a fairly good yield. In the experimental sowing of winter varieties in the spring of 1930 at the Ilyich Commune of the former Mariupol Okrug, spring-sown Ukrainka yielded 29.5 c. on 1.1 ha. (27.3 c. per ha.); at the Batrak Ukrainy Artel, vernalized Ukrainka, sown on 1.5 ha., yielded 32.6 c. (21.4 c. per ha.). At the Pervoye Maya Commune 6.9 c. were obtained on two-fifths o a ha. (17.2 c. per ha.). On the Oktyabrskaya Revolutsia State Farm in the former Stalino Okrug, spring-sown Ukrainka yielded 13.3 c. per ha. A number of other examples could be cited of experiments in the spring sowing of winter wheat made in 1930 on collective and state farms resulting in good yields. It must be emphasized, however, that these examples do not by any means show that any vernalized winter variety can be sown in any district and produce good yields. Not every winter variety will produce a good crop in every district. [25] [26] The yield will depend upon the variety taken for vernalization, as well as upon the. conditions under which the given variety is grown.

Fig. 4. Ferrugineum 1388/1
Sown in Ganja on April 15 presowing vernalization lasts 51 days, alter which the wheat ears

 

Fig. 5. Winter vetch. Spring sown in Ganja
The vernalized plants flowered; the unvernalized plants did not flower

 

1For a brief description of the technique of vernalization see pp. 32-33.

By quoting the above examples of yields obtained from the spring sowing of the vernalized winter wheat Ukrainka, we merely emphasize that the rather important fundamental scientific problem of the causes responsible for the failure of winter varieties to ear when sown in the spring was definitely solved by Soviet science in the collective- and state-farm fields, i.e., under practical farming conditions. In the process of vernalizing seeds under practical farming conditions, the technique of preparing the sowing material of winter varieties for spring sowing was worked out. This technique can already be employed for practical purposes. The method of vernalizing winter varieties employed for the first time (by D. N. Lysenko) in 1929 (seeds beginning to germinate were collected in a sack and buried in snow) and proposed in 1930 has now been considerably altered. The vernalization of sowing material is now done not in sacks, and not in snow, but in ordinary barns, granaries and sheds.1

The technique of vernalizing spring varieties of cereals was worked out simultaneously with the technique for winter varieties.

Thanks to the mass state- and collective-farm experiments, not only was the technique of vernalizing winter and spring cereal crops worked [27] out, but considerable progress was made in elaborating the theory of controlling the vegetative period of different agricultural plants.

Today many people already know that it is possible to vernalize not only winter but also spring varieties of rye, wheat, barley, vetch, rape and other crops. Moreover, it is possible to vernalize plants like millet, cotton and a number of other crops, which in practical farming are never called winter crops. By suitably treating (vernalizing) the seeds it is possible to grow many so-called cold-loving plants when sown under hot spring conditions; or to grow certain thermophilic plants in districts where the temperature is not high enough for them; or to grow "short-day" plants under "long-day" conditions. All this has become possible only because of the creative initiative of collective-farm experimenters, combined with the work of research institutions in studying the development of the plant organism (from the sowing to the ripening of seeds).

Thus, our research work on the vernalization of agricultural plants did. not begin in 1929 (the year when the term "vernalization" appeared). It is organically connected with our earlier work (in 1926-27) on changing, under field conditions, the behaviour of late-ripening varieties of different crops into that of early-ripening ones.

The sowing of vernalized Ukrainka under field conditions by D. N. Lysenko in 1929 served as valuable confirmation of our three years' study at the plant-breeding station in Azerbaijan of the length of the vegetative period.

Let us now deal in brief outline with the chief general features in the development of annual seed plants as we see them today.

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