1 104 PLANT BREEDING 



of K2O were required, on the average, for the production of 100 grnis of 

 saccharose. 



(C) The quantity of sodium ions assimilated is related to the quantity 

 of potassium ions, but, according to the analyses made, this relation varies 

 very much. 



S57 - " Thule", a Variety of Wheat -suited to Central Sweden. — nillson-ehle h., in 



Sveriiies Utsddcfdycmm^s Tidskrifl, XXV th Year, Part I, pp. 5-23. Malnio, i'>i6. 



During the period 1889-1913 wheat growing in vSweden increa.sed al- 

 most twofold, thanks chiefly to the selection work carried out at the expe- 

 rimental Station of Svalof , for the purpose of combining in a single variety, 

 the " high productive character of the best types with the " cold resistance " 

 character of the native Swedish wheat. 



The increased productivity of grain however was anj'thing but uniform. 

 From a maximum of 200 per cent in the districts of Hallands, Malmohus and 

 Kristiastads, and generally throughout Southern Sweden (Scania), a mi- 

 nimum of 20 to 30 per cent is reached in the central provinces (vSvealand) . 

 What is the season of this? In Scania, during the period 1889-1913, the 

 native wheat was graduall}' replaced by more productive kinds, while the 

 area sown also increased. On the other hand in Svealand this substitution 

 was only possible within very narrow limits, chiefly owing to the special 

 climatic conditions, which involved very cold winters and long periods 

 of drought in summer. For the wheats to be cultivated in the central 

 pro\dnces, therefore sufflcient cold-resisting powers and earliness are required 

 to ensure normal ripening and a good yield of grain. These circumstances 

 render the work of hybridisation and selection very difhcult, as it is 

 necessary to exclude some of the types which, though among the best in 

 point of yield, are not sufiiciently resistant to low temperatures. On the 

 other hand, the increase of the area under wheat in vSvealand, the good 

 quality of the soil and the conditions of the agricultural environment, which 

 are as favourable as possible, full}' ju.stify all the investigations and work 

 which have for their object the creation of types better adapted to the 

 climate, and at the same time having a high cropping power. 



From 1904 onwards the writer has been working at the following pro- 

 blems ; i) the improvement of local native types by selection ; 2) creation 

 of new kinds by crossing with the native form ; among these crosses the best 

 results were obtained by hybridising the native with the " Pudel " ; and af- 

 terwards, by perfecting the restdting products by continuous work of selec- 

 tion a new variety was fixed, Thule I, presenting the following scheme of 

 characters : 



I'udcl riiulc N.itiv. 



Productivity + H- — 



Resistance to cold — ( H- ) -f- 



Resistance to rust -{- (+) — 



Rigidity of culm + + — 



Earliness — (-f) -)- 



Quality of grain — (-|-) -|- 



