101 



Experiments in different districts and on different soils are also neces- 

 sary as a means of indicating in what direction improvement should go. The 

 breeder must seek, as far as possible, to know the character or characters 

 which determine the suitability of a sort for given conditions. As has already 

 been pointed out the behaviour of many sorts at Ultuna and Lulea is often 

 quite the reverse of that at Svalof. Oat sorts at Svalof, for example, which 

 show but relatively little difference in dates of ripening are found in the North 

 to differ very decidedly in this respect. Wheat sorts which are weak strawed 

 at Svalof may be relatively strong at Ultuna. Certain sorts are found to 

 be very susceptible to rust and other diseases at Svalof while at Ultuna and 

 elsewhere they are relatively resistant. The reverse may likewise be the case. 

 In developing a rust resistant sort for the latter place, selections made at 

 Svalof might be quite susceptible to this disease, a fact which is exceedingly 

 confusing. 



It has been found very difficult accurately to estimate yields of autumn 

 wheat sorts on account of the varying conditions with which this crop has 

 to contend. Thus the different degrees of hardiness and the varying attitudes 

 of the different sorts toward disease makes it absolutely necessary that tests 

 extend over a long term of years in order that all contingencies may be met. 

 A good example of the confusing effects of disease is afforded in the frequent 

 occurence at Svalof of Leptosphsera, a disease which manifests itself in lodging 

 of the straw. This disease seems particularly insidious in the case of the 

 common Swedish wheat and certain other varieties such as Selected (Renodlad) 

 Squarehead and Tystofte Stand. During the bad year of 1907-08 the two 

 latter sorts were among the poorest, while in good years they are rated among 

 the best. In working with pure lines the need for extensive local trials seems 

 even more urgent than in the case of mixed varieties. As previously pointed 

 out, mixed varieties may contain strains capable of thriving under a variety 

 of conditions. Pure lines on the other hand are likely to be adapted to more 

 specific conditions and thus are less likely to thrive to advantage over so 

 wide an area. 



Local trials on a comparatively large scale are conducted by the Central , , 

 Institution for Agricultural experiments (Central anstalten for forsoks- ^ y the 

 vasendhet pa jordbruksomradet) Stockholm, in co-operation with the Government. 

 various agricultural societies and the Swedish Seed Association at Svalof. 

 All trials in a given district are supervised by the representative of that 

 district who reports the results both to the government and to the 

 Association. 



The general plan recommended for the conducting of local tests is as 



follows (38, p. 37): f^ 0/ 



local sort 



trials. 



1. A location must be chosen in which the soil is as even as possible in 



quality and which is sufficiently well drained. 



2. The plots must not be smaller than 50 square metres (1/82 acres) 

 and each sort should be allowed at least two plots which should not adjoin 

 each other. 



