Hayes and Garber - Cucurbit Breeding

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, this 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 (Pucdnia 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 inheritance
and develop a standard technic of operations. In all
crosses the F% 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-