134 BREEDING CROP PLANTS 



A Wheat Cross Made at Svalof. The highest yielding winter 

 wheat grown at the Svalof Station, reported by Newman (1912), 

 was a cross, Extra Squarehead II, No. 0290. This wheat is 

 one of the offspring of Old Extra Squarehead X Grenadier II. 

 It combines the winter-hardiness and rust resistance of the former 

 with the stiff straw and high yield of the latter. As an average 

 of four years' trial at Svalof and Alnarp, 1his wheat has yielded 

 18 per cent, more than Old Extra Squarehead and 8 per cent, 

 more than Grenadier II, which was next. No variety of winter 

 wheat has proved so generally popular among the farmers of 

 southern Sweden as Extra Squarehead II. It may be of interest 

 to point out that preceding the cross, hundreds of selections out 

 of Grenadier II were examined in search of a pure line with the 

 combination of rust resistance and high yield. 



Wheat Breeding at University Farm, Cambridge, England. 

 Most of the wheat varieties grown in England are very susceptible 

 to yellow rust (Puccinia glumarum). Biffen (1917) set himself 

 the task of breeding a high-yielding, resistant form. He crossed 

 American Club, which is very resistant to this parasite, with 

 several susceptible varieties in order to study the mode of in- 

 heritance and develop a standard technic of operations. In all 

 crosses the F z generations showed monohybrid segregation with 

 resistance behaving as the recessive. The resistant individuals 

 were rather clear-cut, although they sometimes exhibited uredinia. 

 The susceptible plants showed a wide range of variation. No 

 recognizable morphological character has been found correlated 

 with resistance. 



The constancy of resistance in wheats of hybrid origin has also 

 been studied by Biffen. For the purpose he used a resistant 

 strain produced from a cross between American Club, a resistant 

 variety, and Michigan Bronze, which is one of the forms most 

 susceptible to -yellow rust. During eight years of observation 

 the hybrid variety proved just as resistant as the American Club. 



A resistant variety of Russian origin, found among some 

 Gurka wheats, which was not adapted to local conditions, was 

 crossed with Square Head's Master, the variety most commonly 

 grown in England. Among the resistant offspring is one that 

 gives considerable promise. Comparative trials of this wheat 

 (Little Joss) over a period of seven years show it to yield about 4 

 bu. per acre more than the best of the English and French wheats. 

 The explanation for this would seem to be that Little Joss in- 



