The Situation in Biological Sciences, p. 109-110 (1948)
P. F. Plesetsky

Hardier Peaches

The problem of extending southern fruit cultures northward can only be solved, and is being solved by us, on the basis of I. V. Michurin's teaching. I might cite as an example the new varieties of peaches produced under conditions obtaining in Kiev.

The Institute has produced and is now propagating a peach variety, No. 981, which ripens at the end of July (this year it ripened on the 20-23 July, that is to say, simultaneously with the earliest maturing peach varieties cultivated in the extreme South of our country). The average weight of a fruit is one hundred grams. The colouring is bright red. In flavour it is no worse than the best peach varieties cultivated in the South. (Some of the comrades here present can confirm this.) The original parent of this variety perished in the severe winter of 1939/1940. The strain was grafted on various stocks. All grafts perished during the German occupation. Only a graft on a blackthorn survived the severe winters. This year it has yielded a large crop, and this is the case also with the little trees obtained by propagating the grafts on blackthorn. The use of blackthorn as stock has induced radical changes in the peach seed plant: it has become more frost-resistant and earlier maturing, while its flavour has remained good.

In the course of the production of new peach varieties one more extremely important fact has been established: the influence of the stock on the scion, which has led to pronounced changes in the scion. One peach form was grafted on an apricot. When the peach plant began fruiting the fruits were gathered and the stones planted. The seedlings, 42 in number, began to fruit this year. On six of them the fruits have been found to be entirely destitute of pubescence which is characteristic of all peach forms.

This fact is important not only as bearing on the extent of the influence exerted by the stock on the scion and the possibility of making use of this influence to obtain entirely new forms, but, in our opinion, it helps to explain the appearance of the nectarine which is extensively grown in the United States of America.

Similar facts might be cited on the basis of the work to produce new cherry varieties. The Institute now possesses new forms of cherries not inferior to the best West-European varieties as regards flavour and other qualities, and greatly superior to them as regards frost resistance.

The division by the Mendelist-Morganists of the plant organism into hereditary substance and soma has led to the assertion that only modificational variations are possible within a clone, and that, therefore, selection within a clone is useless. But the facts show that selection within a clone is an effective method of increasing the yields also of plants propagated vegetatively.