Gardeners’ Chronicle (Ser. 3) 24: 246 (October 1, 1898)

THE EFFECT OF THE GRAFT ON THE FLAVOUR OF THE FRUIT
Scion

*Gardeners’ Chronicle, vol. xviii., June 25, 1898, p. 397.
THE GRAFTING OF THE GRAPE-VINE.— In reference to the articles which have appeared in these pages on the Vine and its habit changing under the influence of the stock on which it is grafted, and vice versa, it would be interesting to know if the flavour changes as well as the growth. It is just likely that the quality of many of our coarser varieties of Grapes could be greatly improved by a choice of certain stocks upon which to graft. But those who cultivate the Vine extensively will be able to advise on this matter, and many readers of the Gardeners' Chronicle will find pleasure and profit from reading such experiences. Excelsior.

The influence of the graft on the Grape-vine was discussed in these columns a short time ago, and a correspondent suggested the record of observations relating to the effect of the operation upon the taste of the fruit.* It is a suggestive and an instructive fact that no further information on this point has been published, for, however difficult it may be, by means of carefully-conducted experiments, to trace the reciprocal effect of the scion on the stock, and vice versa, as regards accurate results in general, still more difficult is it to obtain authentic data relating exclusively to the sense of taste which, in this connection, is so easily deceived by the eye and by the imagination.

That the graft does exert some influence on the taste of the fruit appears indisputable from the classic experiments of M. Daniel, to whose work reference has frequently been made in this journal. He has recorded, for instance, that when the black Belgian Haricot, whose pod has an agreeable taste, is grafted on a Soissons Haricot, which has a particularly disagreeable flavour, the Bean which is produced on the grafted plant acquires to a pronounced degree the taste of the fruit of the plant which has been used as the stock. Similarly, he has shown that when the Savoy Cabbage is grafted on the Turnip, the former acquires the very characteristic taste of the latter plant.

In each of these eases, however, the observer dealt with a plant possessing a particularly marked taste, which was consequently the easier to detect; hence it is much more difficult to trace the effect of the graft in relation to plants the taste of whose fruit has a certain affinity, and which has not, as in the case of, say, the Onion family, any marked and distinguishing characteristic.

The most interesting work, as regards the importance of its results, which has ever been undertaken in horticulture in connection with the graft, is undoubtedly that which relates to the reconstitution of vineyards destroyed by the phylloxera. Certain American Vines whose roots resist the attacks of the insect are employed as stocks, whereon are grafted native Vines, which, thus protected, continue to yield fruit "after their kind." Now, it is an important and admitted fact that, apart from certain other results to which allusion need not now be made, the graft of European on American Vines does not alter the quality of the wine. The soils which gave noted wines under the old regime, says M. Ravez, the Director of the Viticultural Station at Cognac, yield the same product with Vines grafted on imported stocks, and nothing is changed from this point of view. Similarly, in his work on The Principal Varieties of Vines, M. Cazeaux states that whilst grafting on American stocks may deepen the colour of the Grapes, and of the red-wine produced therefrom, whilst the maturity of the fruit may thereby be improved and hastened, the operation of the graft does not affect the taste, or the perfume, or the bouquet of the produce; and other authorities might be quoted to the same purpose.

*Gardeners' Chronicle, March 27, 1897, pp. 206-207.

It does not, however, follow that the operation of the graft has no effect whatever on the taste of the fruit, merely because the quality of the wine which is produced retains its old established reputation, inasmuch as recent experiments with other plants tend to show that one of the effects of the graft, when suitably applied, is indeed to ameliorate the savour of the fruit. A full account of experiments which corroborate this statement has been recorded in these columns,* where it was stated that "fruit-trees in general, and certain Pear-trees in particular, undergo changes according to the nature of the stock. The taste of the fruit, for instance, varies when the scion is grafted on Pear-stock, and when it is grafted on the Quince."

It must, moreover, be remembered that the theory of the graft has been completely altered during the present decade. The orthodox opinion on the subject implied that hereditary variation was purely of sexual origin, and, in a text-book which was published less than seven years ago, one of the most distinguished European botanists stated that the graft is a valuable means of fixing and conserving all the variations introduced into the embryo, because the process itself does not produce the slightest variation.

A very important communication on this subject was read at the recent horticultural congress in Paris, and afterwards at the Academic des Sciences. The author, M. Daniel, gives a résumé of all the experiments which he has made relating to the reciprocal influence of the scion on the stock, and vice versa, including the effect on the taste and quality of the fruit. The fact which gives so much value to M. Daniel's experiments is due to their comparative character, that is to say, the grafted plant has in each case been grown side by side with a normal plant. Now, however interesting any single result of the graft may be, it loses all its value, says M. Daniel, unless it be compared with a control plant, grown under exactly the same conditions as the grafted plant (the operation itself excepted), hybridization being of course avoided. This factor, however, implies an amount of labour and patience—not to mention expense—which are quite beyond the means of the ordinary horticulturist, and it is to the absence of this comparative element that M. Daniel attributes "the old-established legend of the graft, the outcome of contracted observation, of results wrongly interpreted."

However it may be, M. Daniel has grown his plants and conducted his experiments in the full light of day, under the eye of well-known scientific men who bear witness to the genuineness of the work. It is not possible to give more than the following abstract of the results, which have, moreover, been published in detail in the Mémoires of the National Horticultural Society of France:—

  1. The reciprocal influence of the scion and of the stock cannot be denied, even though it may not always act with the same intensity.
  2. This influence may bear on the general nutrition of the plant, and indirectly on its size, vigour, and resistance to parasites; or it may affect the internal and external morphological character of the plant, including its organs of reproduction, e.g., the fruit.
  3. Those variations are frequently of an hereditary character, and appear during the course of the second generation.
  4. This effect of the graft offers several practical advantages, viz, the production of larger and "better" fruit and vegetables (such as an improvement in their taste); and the direct production of new varieties, e.g., a modification of the colour of flowers, of the shape of fruit, &c.
  5. The effect is more marked in herbaceous than in ligneous plants, and on the progeny of the grafted plant than on the plant itself.
  6. The graft, which produces variation in the seed, may be employed to produce new varieties. The variation may frequently be diverted culturally, so as to impart, almost assuredly, after repeated graftings, certain qualities (taste, shape, colour, &c), to a plant which did not originally possess them, and which varies easily under cultivation. As regards other plants, the graft still affords the means of obtaining variation, however difficult it may be; and as soon as the change is observed, it can be pursued in the desired direction, and with good results.