Gardeners’ Chronicle, pp. 140-141, February 2, 1895

On obtaining Hybrids by Grafting

This subject, to which we have already referred, but which is worthy of more extended notice, was among the last communications presented to the French Académie des Sciences, by Professor DUCHARTRE, whose death Horticulture has recently had to deplore; and one by M. LUCIEN DANIEL relating to the creation of new varieties by means of the graft.

Is it possible, asks M. DANIEL, to obtain new varieties from the seeds produced by grafted plants? And he answers that, although the subject is an old one, no precise or satisfactory explanation has yet been given, owing perhaps to the fact that it has been investigated mainly in connection with trees, the growth of whose seeds into mature plants takes so long that human life is almost too short to permit the deduction of conclusive results.

But by making experiments on annuals and biennials, and grafting various alimentary plants, M. DANIEL has shown that the period necessary for the due observation of the effect of grafting may be so shortened that it is possible to obtain results, as well from a practical as from a theoretical point of view, which are of the highest importance to Horticulture.

A detailed account of his investigations are contained in the Comptes Rendus, where it is stated that the problem presents three solutions:—(1) The young plant grown from seed produced by grafted individuals may tend to revert to the wild type, in which case no useful practical results would follow; or (2), the young plant may retain the ancestral characters of the variety, in which case the graft would permit the indefinite reproduction of varieties produced by other means; or (3), the scion—altered in form and savour by a more or less lengthened contact with another plant supplying nutrient matters differing in quality and quantity from those which would hare been produced under normal conditions—may endow its seeds with new qualities which will themselves be transmitted to the offspring.

A new field of research would in this case be open to horticulturists, viz., the possibility of creating varied types possessing qualities derived both from the scion and from the stock. When M. DANIEL grafted the Turnip on Sisymbrium Alliaria, a wild cruciferous plant common in hedgerows throughout temperate Europe—in England it is known under the various names of Garlic Mustard, Sauce alone, and Jack-by-the-hedge—he obtained plants which showed a marked reversion to the wild type. When seeds of S. Alliaria and seeds produced by S. Alliaria grafted on the Cabbage were sown in adjacent beds, the former naturally reproduced the wild plant with leaves of a yellowish-green colour, and which had a very distinct odour of Garlic, which is so noticeable in Garlic Mustard. The plants in the other plot were not so tall, their leaves were much more compressed together, and they bore a very characteristic likeness to the Cabbage plant. These leaves were of a deeper green colour than in the wild plant; somewhat plaited like the Cabbage leaf, and with a less marked smell of Garlic, but combining with it something of the odour of the Cabbage leaf.

Modifications from the wild type were similarly obtained in the internal structure. The roots of the plants issued from grafted subjects were less lignified, their soft medullary tissue was scarcely thickened, their vascular cylinder was of smaller dimensions, and their liber was much more developed. The stems had also less fibrous tissue, and consequently were more tender; they contained more chlorophyll, and the pith did not show the intercellular spaces of S. Alliaria. The leaves, however, were not different in their internal structure, although they also contained more chlorophyll or green colouring matter.

Turnips from normal seed grafted on Mortagne Cabbages gave equally characteristic results. The plants obtained produced Turnips smaller than ordinary ones, having a flavour of both the Turnip and the Cabbage.

M. DANIEL remarks, however, that his observations only relate to the first generation, and that they do not necessarily indicate what may happen in succeeding generations, or on repetition of the grafting process. But he infers, that in order to improve a plant by means of the graft, it would appear to be necessary to apply it to another plant possessing qualities of a higher order as regards the nature of the improvement which is aimed at.

* Revue Générale Botanique.

In other words, as M. DANIEL has stated elsewhere,* if seed produced by a cultivated scion on a wild stock be sown, the plants will tend to revert to the wild type, and they will lose, to a great extend, their value as food-plants. He also states that, in grafting, inferior stock should not be selected for grafts, the seeds of which are intended to be sown.

M. DANIEL sums up his conclusions on this interesting subject as follows:—(a) Hybridising by means of the graft is possible with certain herbaceous plants. They can be endowed with new alimentary qualities by grafting them on other plants which possess these qualities to a higher degree, and by sowing the seeds thus obtained, (b) The impression produced on the grafted plants and on their seeds varies with the plants grafted, but it would appear to be the more marked in connection with the Cruciferae.