Richardson: Wheat Breeding 



137 



Some idea of the difficulties which be- 

 set the early workers on this field of 

 inquiry may be gathered from the 

 history of a typical cross-bred seed. 

 Suppose, for example, the variety known 

 as Clubhead, which is a stiff-strawed, 

 beardless, dark-chaffed variety with a 

 dense compact head, be crossed with 

 Yandilla King, which has a long, white, 

 somewhat open head with firm closing 

 glumes. The plants of the first genera- 

 tion will invariably be slightly clubby in 

 character with reddish-brown chaff. 

 Now from this single cross-bred plant a 

 thousand seeds might be produced. If 

 every one of these seeds be separately 

 sown the next season an unending 

 variety of plants will arise. 



Every gradation and combination 

 between the characteristics of the Club- 

 head on the one hand and the Yandilla 

 King on the other appear to make 

 themselves manifest in this generation. 

 Indeed, characters appear in this genera- 

 tion which were latent in the originals, 

 e. g., many of the progeny will be found 

 with beards. Apparently chaos is the 

 result of this simple act of crossing. 

 Further, if a few grains be selected from 

 each of the thousand plants and again 

 be sown separately, it will be found that 

 in the third generation some of the plants 

 breed true to type whilst others give 

 still further complex variations. This 

 apparently chaotic result arising from 

 the growing of a single cross-bred seed 

 puzzled and confounded the early 

 hybridizers and investigators. If by 

 cross-breeding plants possessing specific 

 characteristics the progeny were found 

 to obey no definite laws it follows that 

 the improvement of plants by this 

 method would be nothing more than a 

 mere gamble. 



Lindley, indeed, some fifty years ago, 

 declared that the improvement of plants 

 by cross-breeding was a game of chance 

 with the odds in favor of the plant. 



If, on the contrary, the laws of in- 

 heritance of specific characteristics could 

 be formulated and definitely known it 

 manifestly follows that the work of 



plant improvement would be reduced to 

 scientific exactness. 



Gregor Mendel, monk and abbot, of 

 Briinn, in Austrian Silesia, was the 

 first to unravel this tangle, and present 

 to the world a clear and lucid exposition 

 of the inheritance of specific characters 

 in cross-breeding. 



Mendel's work has been confirmed by 

 many workers in widely different fields 

 of investigation. Besides Correns, 

 Tschermak, and De Vries, who were 

 responsible for the rediscovery of Men- 

 del's work, there have been confirma- 

 tory contributions by Darbishirc on 

 Mice, Hurst on Rabbits, Davenport on 

 Poultry, Vilmorin, Nilsson-Ehle, Biften, 

 Spillman, and Howard on Wheat, 

 Bateson, Saunders, and others on Ly- 

 chnis, Atropa and Matthiola, and To- 

 yama on vSilkmoths, to name only a few. 



MENDELISM IN WHEAT. 



It is of great practical importance to 

 know whether the laws of inheritance 

 formulated by Mendel and developed 

 by his successors may be applied in 

 practice to the improvement of wheat. 

 A considerable amount of data has 

 accumulated during recent years on the 

 inheritance of unit characters in wheat, 

 and this tends to show that — 



(1) The process of "fixing" new 



crosses, which formerly required 

 considerable time and a vast 

 amount of labor, may be 

 greatly simplified. 



(2) The wheat breeder can predict 



with a tolerable amount of 

 certainty what combinations of 

 unit characters may be asso- 

 ciated and fixed in a new 

 variety. 



(3) The breeding of new varieties 



possessing certain specific attri- 

 butes and desirable qualities 

 may be accomplished with cer- 

 tainty. 

 The most prominent investigators in 

 this field of work are Tschermak,'^ 

 Spillman,'^ Biften,'* Nilsson-Ehle,'" and 

 Howard.'* The first essential, of course, 



" Tschermak — Die Ziichtung der landw. Kulturpflanzen Bd. IV., 1907. 



'5 Spillman—Science XVI, 1902. 



" Bifen— Journal of Agri. Science, 1905, 1907, 1908, 1909. 



'^ Nilsson-Ehle — Kreuzungsuntersuchungen an Hafer und Weizen Lund, 1909-1911. 



'* Howard — Memoirs of the Imperial Dept. of Agric, India, Vol. IV, No. 8, Vol. V, No. 1. 



