122 



PLANT BREEDING IN SWEDEN 



crosses, however, were made without any special object, although perhaps in some 

 cases with the hope of getting a practically useful result from some of them. 

 Crossing was at that time generally considered as a way of stimulating or produ 

 cing a variation. It was not until after the discovery of the Mendelian laws of 

 segregation that artificial cross*fertilization became used systematically with a defi* 

 nite purpose and to a great extent. The honour of having applied these laws 

 in the practical breeding work is due to NILSSON*EHLE, who at once understood 

 the value of this discovery when improving both oats and winter wheat especi* 

 ally. It is easy to understand that the winter wheat in this case was especially 

 easy to work with. It now became the chief aim of the workers to combine the 

 high yield of Squarehead wheat with the hardiness of the old native land sorts 

 to a greater extent than they had hitherto been able to do by line selection. 

 When improving barley and oats, on the contrary, there have been no such 

 decisive characters of yield to work with. There have been no foreign sorts of 

 barley and oats either, which have been as superior to the old Swedish sorts as 

 Squarehead to old Swedish land wheat. At the beginning nobody hoped, not 

 even NILSSON*HLE himself, that the yielding power of the former and the hardi* 

 ness of the latter could be combined to so great an extent as has now been done 

 by him. 



The purpose of crossing sorts with characters of different degrees of value, 

 for practical use, is to produce new combinations of characters which from a practical 

 point of view are still more valuable. Cross-breeding is a combination*breeding. 

 The way of working and the results already gained are clearly shown in the 

 following scheme, borrowed from NILSSON*EHLE. The numbers in parenthesis 

 give the average yield of the trials made at the Association at Svalof. These are 

 expressed in relative numbers compared with Svenskt Sammetsvete (Swedish 

 Velvet Wheat) = 100. One of the sorts has no name and is therefore called 

 by its stock book number 0516; a stock book number is in reality a substitu* 

 tion for a name and is used in all tables, genealogical schemes, field books etc. 

 were the sorts are mentioned. 



SUMMARY OF PART OF THE CONTINUED COMBINATION WORK WITH WINTER WHEAT AT SVALOF. 

 Sklne Land Wheat (102) English Squarehead Wheat (99) 



0516 



(121) 



r~~-.. \v/l,.,t ma\ v Grenadier .. Extra Squareh. 

 Cone Wheat (128) X wheat ( , 21) X whMt j (m j 



Sun Wheat (131) X 



Poodle Wheat X 



. Extra Squareh. Wheat II (129) X Small Wheat (131) 



Swedish Velvet 

 Wheat (100) 



Sun Wheat II X Iron Wheat (140) X.-,.- Fylgia Wheat (135) X (Sun Wheat II) X /^"e'wheaHI X ^'wheat' 1 ' 

 Fi 1915 F3 1915 Fi 1915 Fi 1915 F2 1915 



To describe the different characters of the crossed sorts more closely and 

 the purpose of each cross would take too long time. Iron Wheat, for instance, 

 has inherited good winter=hardiness and a high degree of resistance against yellow 



