The Situation in Biological Science: pp. 298-299 (July 31-August 7, 1948)
Eggplants on Perennial Tomato; Citrus Hybrids
F. M. Zorin

One of the participants of this conference has described the Sochi Experimental Station as the Siberia of the subtropics. This seems to be a most fitting comparison. The late Academician Boris Alexandrovich Keller called it the northern outpost of the subtropics, on account of its location at the extremity of the northern frontier of the possible extension of citrus cultures. This is why the work of this station is entirely devoted to problems connected with the cultivation of highly valuable subtropical plants and their extension farther North.

The staff of the station solves these problems by developing scientifically tested agrotechnical methods for cultivating these valuable cultures and breeding new varieties better adapted to local conditions.

We base our work on the methods evolved by that great transformer of nature, I. V. Michurin, and by his eminent continuator, Academician Lysenko.

The work of the Sochi Experimental Station in the abovementioned field, has been dealt with in sufficient detail in the press. Moreover, many of the participants of this conference have no doubt visited the station and acquainted themselves with our plants and experiments, when on vacation at Sochi. I shall therefore not stop to deal with a number of investigations which though important are sufficiently well known. I shall dwell briefly on certain methodical problems which we have been able to solve in recent years while pursuing our main line of research.

Our experiments have been based on Michurin's mentor theory and Lysenko's theory on heredity and its variability. We have proceeded from the principle that it is unthinkable in our times to conduct theoretical or practical work in the field of plant breeding if it is not based on this theory of Lysenko.

I must say that in the outlying districts of our country Lysenko's Agrobiology has become so scarce, is such a rarity, that I think I shall make no mistake if I suggest that it is high time that this book, as well as other of Lysenko's writings, should be published in large editions.

Michurin's mentor method has been used by us in relation to the reproductive organs of plants, and in this way we have arrived at a new method of combining sexual and vegetative hybridization and have disclosed the possibility of obtaining hybrids from three and more different parental forms simultaneously.

Every living organism is known to build its body out of the elements that go to make up its environment, and does so in accordance with its nature, its heredity. By virtue of heredity organisms that grow up under the same environmental conditions are distinguished from, one another by different qualities, by the degree of resistance to frost or drought, by the period of fruit ripening, external appearance, chemical composition, productivity and so on. Thus a number of highly valuable characters and qualities required for breeding work are not concentrated in a single plant but are rather scattered among various plants. The task of the breeder is to bring together in a single plant, or rather within a single variety of plant, as many useful characters as possible. The best way to achieve this is by combining sexual and vegetative hybridization.

Our method consists in fertilizing the flowers of one plant with the pollen of another, and grafting the pollinated flowers on a third plant.

The three plants (of which two are used as the initial form in sexual hybridization and the third is used as a mentor) are so chosen as to possess different useful qualities.

The fruit that develops from the ovary of the grafted flower will take up food from the elements supplied by the leaves and roots of the mentor.

If the components are aptly chosen the fruit may be altered externally beyond recognition by the influence of the mentor. We may say, altered externally and internally, since for us Michurinists, the change of external characters means a change of internal characters also. It may happen that the external characters of the fruit do not change, and that only, the seeds appearing in the fruit do so. And it may happen again that neither the seed nor the fruit show any alteration of external characters. In that case the flowers formed on the plants grown from the seed of the grafted fruit will have to be grafted for a second time on the same mentor.

Our experiments are conducted with perennial fruit plants, whose seed-to-seed cycle extends over a number of years. Therefore it is hard to make a rapid check on whether the modifications thus induced by environmental action are or are not transmitted by heredity.

In order to clear up this question we also conducted experiments on annual plants. These experiments were conducted with two varieties of Phaseolus: Mont d'Or with black seeds, and Giant with green pods and yellow seeds. Buds from the black variety were grafted on the yellow one, and conversely. When the fruits formed it was found that the seeds in the pods were unaltered by either grafting. It appeared as if the representatives of the formal school in biology were right. The environmental action had no effect whatsoever. However, we made repeated graftings and found that in one case the yellow seeds were transformed into black ones, and in another the black seeds began to be transformed into yellow ones. I have brought these seeds to the conference as material evidence.

We planted the altered seeds without grafting and in two generations have obtained above three thousand seeds with altered heredity.

Similar experiments have been made by us on other plants, annual as well as perennial.

Flowers of the eggplant, for instance, were grafted on perennial tomatoes. For three years we failed to effect the grafting. In 1946 one of the flowers healed in, and the ovary formed from it began growing and attained the dimensions of a medium-sized gooseberry. After that it stopped growing for a long time. At length, 2 1/2 months later, the ovary resumed growth, but now it was growing in an unusual way, suggestive of a gumboil. Somewhat later the fruit began growing on the other side, and successively assumed all sorts of shapes until its growth was complete. A similar variability of successive colours was also observed. At last the fruit was ripe. It was found to contain 643 seeds. Of this number 641 seeds were like eggplant seeds, and two differed entirely both from eggplant seeds and the seeds of the perennial tomato.

We planted these two seeds. One failed to germinate, but the other did. The plant grown from it was quite unusual in appearance, but it perished, and so I will not describe it. The remaining 641 seeds were perfectly alike. I thoroughly examined them under a magnifying glass, but try as I did, I was unable to discover the slightest difference between the seeds. I then decided to plant them, and at the same time planted some seeds of perennial tomatoes for checking purposes. Seedlings appeared, but as was the case with the seeds, not a single characteristic difference between them could be recorded.

A flea beetle attacked the seedlings, and began to destroy them. I was about to use pyrethrum in order to protect the plants from the flea when suddenly something attracted my attention. I noticed that some of the seedlings were not attacked by the fleas at all, and the seedlings of the perennial tomato were not attacked either. I have already published my observations (some of you have probably read my article in Sotsialisticheskoye Zemledeliye [Socialist Agriculture]) on "helpers without diplomas." Here is another case of the same kind.

I abstained from using the pyrethrum, and let them act freely. The result was that all plants but five were destroyed by the fleas. These five plants were not attacked at all though to outward appearance they were similar to the plants destroyed. It was obvious that in some respect at least these plants were similar in chemical composition to the perennial tomato plants.

A long interruption took place in my work on account of illness, but this year the grafting experiments were resumed.

At the time I left for this session the eggplant fruit grafted on perennial tomato displayed considerable alterations. There was no possibility of a sexual process having taken place, inasmuch as there had been no flowers on the tomato. The fruit of the control plants are pearlike, larger in the lower part, whereas the grafted fruit is sharp-pointed, similar to perennial tomato fruit.

In the preceding years we made similar experiments with the ovary of plums. We succeeded in effecting considerable changes in the colour of the fruits, from red to blue and from blue to red.

Last year flowers of a mandarin-orange hybrid taken from one and the same branch were grafted on orange and on mandarin. The fruits that grew from these flowers were found to have changed, but particularly characteristic were the changes observed in their seeds. From these seeds plants have been grown, which also show characteristic alterations.

All this evidence goes to prove that the only correct theory in biological science is that of Michurin, which allows the plant breeder to direct the process of development.

Of the other experiments made at the station I should like to mention the following:

Citrus hybrids require much time before they bear fruit. They do not come to fruit until the age of 7-15 years, or even later. Yet among grapefruit seedlings cases have been observed of fruiting in the first year of life. Formerly these phenomena were regarded as curiosities. But Michurinists consider them in a different light. From the seedlings that came to flower so early we took the pollen and transferred it to different citrus plants. This year early flowering was observed, not, however, in occasional instances, but on a mass scale. These seedlings formed ovaries, which attained the size of a cherry, but such fruits dropped afterwards, for reasons unknown to us. We are continuing our study of this problem. It will certainly be solved, and we hope to secure citrus hybrids that bear fruit at an early date.

That Michurin's theory on the important role of the environment in altering the nature of a plant organism is correct has also been shown by our station's experiments which are aimed at extending the cultivation of tea to the foothill areas of the Kuban, and also to the Caucasus. Tea was planted in all these more northern districts and the seeds obtained were planted again until shrubs were obtained which withstood temperatures of more than 20° C below zero, without a cover of snow. Thus the cultivation of tea is beginning to spread northwards beyond the boundaries of the subtropics.

By using the methods indicated by Michurin, Soviet plant breeders have been able to produce the first home-grown varieties of citrus plants and other subtropical cultures, and are continuing along these lines. (Applause.)

Graft Hybrids