Gardeners’ Chronicle, p 289. (April 18, 1931)

PROFESSOR ERWIN BAUR'S Masters Lectures, delivered recently before the Royal Horticultural Society, contained so much that is valuable to gardeners that when printed they should be read, marked and learned by everyone interested in the raising of plants. Here only the chief points which he dealt with can be mentioned, and those only briefly. Of the several methods which the plant breeder uses to produce new varieties the most ancient of all, that of selection, is Still one which may often be applied with success. Professor Baur gave examples of plant breeding by selection from work which is actually in progress at the Plant Breeding Institute at Munchenberg, mar Berlin, of which Institute he is Director. The light, sandy soils which compose so large a part of Germany could often he more profitably employed than they are at present if they could be used for the production of forage crops. For, despite the attention which Germany gives to its agriculture, that country is obliged to import annually large quantities of feeding stuffs for cattle. The food thus provided, and now purchased from abroad, could be produced at home if plants such as Lupins rich in proteins (albuminoids) could be grown. They can be, and are, of course, eminently adapted for cultivation on light lied, but unfortunately they contain an alkaloid which is apt to be present in the leaves in sufficient quantities to render the Lupin unsuitable, or even dangerous, as a fodder plant. Professor Baur therefore undertook to search for a naturally occurring Lupin plant belonging to one or other of the species commonly grown agriculturally but which lacked all trace of alkaloid. He knew that the search would be long and arduous, and might involve the testing of a million or more plants. Undeterred by the magnitude of the undertaking, he set about it. New methods of testing the leaves for the alkaloid were devised, so that thousands of plants could be examined in a day. Every day these thousands were tested, until at last, after upwards of a million plants had been examined, one was found which lacked altogether the poisonous alkaloid. This property was found to breed true, and so now alkaloidless races of Lupins have been produced which should provide a valuable crop for light land and a large supply of nitrogenous food for the winter keep of cattle. Similar work is being done with another Leguminous plant, Melilotus alba, and selection is also being used successfully to discover a Tobacco without Nicotine, so that the smoker of the future may perchance enjoy all the pleasure without any of the inconveniences which at present attach to the undue consumption of ordinary Tobacco. Selection, however, is but one of the methods open to the plant breeder. Long before the science of genetics was born, nurserymen, fruit-growers and seedsmen had practised with astonishing success the method of combining in one and the same variety characters found naturally in different varieties. This recombination of characters by cross-breeding is still one of the most valuable methods whereby new plants are produced. Professor Baur might have given examples from the pioneer work of Professor Biffin, who, as everyone knows, combined high yield and root resistance, and also high yield and strength of flour, in new kinds of Wheat, produced by crossing varieties each of which is characterised by the presence of one, and not the other, of these two characters. In a similar way this pioneer work has been followed in Sweden by successful recombinations of the heavy yield characteristics of English Meats with the winter hardiness characteristic of the varieties of Wheat hitherto grown in Sweden. By this means an increase of yield amounting to fifty per cent. has been achieved in Sweden, with a consequent great increase of the agricultural prosperity of that country. When we look abroad and see the resources in plant breeding now enjoyed by Germany, Sweden, the United States and Russia, we must be lost in amazement at the narrowness of the resources provided in this country. It was here that Bateson laboured. This country played a large part in developing the science of genetics, but none of our statesmen has had the imagination or the understanding to realise what a mighty means of national prosperity is supplied by plant breeding stations, equipped adequately for the work of producing new and better agricultural plants. To return, however, to Professor Baur's Lectures: The method of recombining characters is now being practised on a colossal scale in Germany in the case of the Grape vine. Millions of marks are spent annually in controlling the Mildew of the vine. If varieties of Grapes could be produced which would combine the quality of those now growing in German vineyards with resistance to Mildew and to Phylloxera, all that and far more would be saved. American Grape vines of inferior quality—so bad, in fact, as to make any country want to go dry—are resistant to Phylloxera, and so Professor Baur has united the produce of the New and the Old World in the hope of making a better and healthier Grape. It is a question of growing many hundreds of thousands, or even millions, of the second generation hybrids, of inoculating each one with the Mildew (Peronospora viticola), and discovering, perhaps, one or two per ten thousand which resist this disease, subjecting them to a second test for resistance to Phylloxera, and then, when the desired dual resistance has been found, using these plants to build up vines which shall be as delectable in the flavour of the wine produced as they are defiant of disease. How great and varied are the possibilities which await the plant breeder was illustrated en passant by Professor Baur, who stated that he had recently returned from Peru where, in the high mountains, he had found many varieties of Potato which are quite resistant to frost. The value of a good edible early variety with this quality needs no emphasising. The third method used by the plant breeder is that of hybridisation, and here again are vast possibilities. Of these, one mentioned by Professor Baur is of especial interest. The light soils of Germany already referred to are suitable for the cultivation of Rye, but not of Wheat. Modern Germany no longer cares for Rye-bread—it prefers white, wheaten bread. Thus it happens that Germany produces a great deal more Rye than it can consume, and actually imports Wheat. Therefore at Munchenberg search is being made for a new hybrid Wheat which will give a fair yield in the light lands, and already the search is being attended with a large measure of success. The sterility of hybrids, which is often a bar to this line of progress, is found not infrequently to yield to the large-scale methods practised by the new generation of plant breeders. Out of vast numbers of the hybrids, it may be after a lapse of years, one or two plants may be found to be grudgingly fertile, and they may offer a new starting point for the quest of better plants. The fourth method practised by the plant breeder is the most interesting of all. He no longer waits, like Mr. Micawber, for something to turn up, in the way of mutants. He makes them. Professor Baur has shown bow this may be done. Plants subjected to X-rays, and also to certain chemicals, lose their normality. Instead of mutation being a rare phenomenon, it becomes common among them. Hence, by these means, as yet but faintly indicated but of great potential potency, the plant breeder may stir up lethargic Nature to start new lines of evolution, the end of which may be new plants of far greater value than those which have evolved under the milder encouragement of unaided Nature.