ART 11
Class I consists of those districts of an altitude of from 4,500 fee
0 6,500 feet (includes Groups No. 8 and 4 districts). Here Puccini
raminis and Puccinia triticina occur, but not Puccinia glumarum.
Class II. consists of districts of about 6,500 to 7,500 in altitude
(identical with Group No. 2 districts). Here all three rusts occur.
Class III. consists of those districts of an altitude of 7,500 feet
and upwards (identical with Group No. 1 districts). Here Puccinia
jlumarum and Puccinia triticina occur. Pu cinta graminis has been
een but does not appear to flourish.
The problem to be solved by the Plant Breeder can briefly be
ostulated as follows:
Four months maturing wheats resistant to Puccinia graminis
have to be bred for Group No. 4 districts.
Four months and six months maturing wheats resistant to
Puccinia graminis have to be bred for Group 3 districts.
Early and long maturing wheats resistant to Puccinia graminis
and Puccinia glumarum have to be bred for Group No. 2 districts.
Early and long maturing wheats resistant to Puccinia glumarum
have to be bred for Group No. 1 districts.
If resistance to Puccinia triticina can be tacked on to .all these
vheats so much the better.
Other important characters which all these wheats must possess
are high yield, strong straw, good milling quality and close chaff (this
ast point being difficult to achieve in a hot climate). One cross doe
ot always produce in the progeny all the characters desired and it i
often necessary to cross some of the progeny again with other wheats
in order to produce the ideal one.
There should be three breeding stations in different parts of the
country with a suitable number of varietal testing stations attached
o them, if the work is to be satisfactorily done.
It may be said at once, why not concentrate all the work at
7,000 feet and breed wheats resistant to all three rusts there which
vouid then be suitable for all parts of the country. The answer to
hat is that the choice of types would be very much restricted and in
any case, it would be necessary to have stations in other districts for
a further testing of types. It would probably simplify the work if
he main breeding station were at 7,000 feet. :
In conclusion a little must be said on what has been done in the
way of producing rust resistant wheats.
One of the differences between wheat and maize is that maize is
heterozygous and wheat homozygous. To produce mutations, and
egregation and recombination of characters, wheat has to be
artificially cross-fertilised. ~~ During the succeeding generations of
atural in-breeding the factors segregate out and pure and desirable
ombinations are eventually obtained. From the date of the original
cross it Is likely to be a matter of at least ten years before an
resulting variety is issued to the public. Many hundreds of varietie
t wheat have been imported into the country, but none of them have
ps of any value agriculturally, and at the same time resistant to
ust. A very few of them have been resistant to one or other of the
rusts and thus have been useful as parents for crosses.
The first Plant Breeder was appointed in 1912. He made a
umber of crosses and produced several varieties of wheat such as
Bunton, Cross 13/5, Cross XI., and Bobs Reiti, which were though
; resistant to rus is work was interrupted bv the war